- Volume 145, Issue 12, 1999
Volume 145, Issue 12, 1999
- Review Article
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- Microbiology Comment
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- Bioenergetics And Transport
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TRAP transporters: an ancient family of extracytoplasmic solute- receptor-dependent secondary active transporters
More LessTripartite ATP-independent periplasmic transporters (TRAP-T) represent a novel type of secondary active transporter that functions in conjunction with an extracytoplasmic solute-binding receptor. The best characterized TRAP-T family member is from Rhodobacter capsulatus and is specific for C4-dicarboxylates [Forward, J. A., Behrendt, M. C., Wyborn, N. R., Cross, R. & Kelly, D. J. (1997). J Bacteriol 179, 5482–5493]. It consists of three essential proteins, DctP, a periplasmic C4-dicarboxylate-binding receptor, and two integral membrane proteins, DctM and DctQ, which probably span the membrane 12 and 4 times, respectively. Homologues of DctM, DctP and DctQ were identified in all major bacterial subdivisions as well as in archaea. An orphan DctP homologue in the Gram-positive bacterium Bacillus subtilis may serve as a receptor for a two- component transcriptional regulatory system rather than as a constituent of a TRAP-T system. Phylogenetic data suggest that all present day TRAP-T systems probably evolved from a single ancestral transporter with minimal shuffling of constituents between systems. Homologous TRAP-T constituents exhibit decreasing degrees of sequence identity in the order DctM>DctP>DctQ. DctM appears to belong to a large superfamily of transporters, the ion transporter (IT) superfamily, one member of which can function by either protonmotive force- or ATP-dependent energization. It is proposed that IT superfamily members exhibit the unusual capacity to function in conjunction with auxiliary proteins that modify the transport process by providing (i) high-affinity solute reception, (ii) altered energy coupling and (iii) additional yet to be defined functions.
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Strategies to determine the extent of control exerted by glucose transport on glycolytic flux in the yeast Saccharomyces bayanus
The extent to which the transport of glucose across the plasma membrane of the yeast Saccharomyces bayanus controls the glycolytic flux was determined. The magnitude of control was quantified by measuring the effect of small changes in the activity of the glucose transport system on the rate of glucose consumption. Two effectors were used to modulate the activity of glucose transport: (i) maltose, a competitive inhibitor of the glucose transport system in S. bayanus (as well as in Saccharomyces cerevisiae) and (ii) extracellular glucose, the substrate of the glucose transport system. Two approaches were followed to derive from the experimental data the flux control coefficient of glucose transport on the glycolytic flux: (i) direct comparison of the steady-state glycolytic flux with the zero trans-influx of glucose and (ii) comparison of the change in glycolytic flux with the concomitant change in calculated glucose transport activity on variation of the extracellular glucose concentration. Both these approaches demonstrated that in cells of S. bayanus grown on glucose and harvested at the point of glucose exhaustion, a high proportion of the control of the glycolytic flux resides in the transport of glucose across the plasma membrane.
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- Environmental Microbiology
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Oocydin A, a chlorinated macrocyclic lactone with potent anti- oomycete activity from Serratia marcescens
More LessA unique chlorinated macrocyclic lactone, termed oocydin A, was isolated from a strain of Serratia marcescens growing as an epiphyte on Rhyncholacis pedicillata, an aquatic plant native to the Carrao river of the Venezuelan-Guyanan region of South America. The lactone has a molecular mass of 470 Da, and contains one atom of chlorine, a carboxyl group and a tetrahydrofuran ring internal to a larger macrocyclic ring. MICs of approximately 0·03 μg ml−1 were noted for oocydin A against such phytopathogenic oomycetes as Pythium ultimum, Phytophthora parasitica, Phytophthora cinnamomi and Phytophthora citrophora. With regard to the true fungi, oocydin A had either minimal or no effect against certain Fungi Imperfecti (including several pathogens of humans), two ascomycetes and a basidiomycete. Oocydin A may have potential as an antimycotic in agricultural applications and especially for crop protection.
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Very similar strains of Halococcus salifodinae are found in geographically separated Permo-Triassic salt deposits
The GenBank accession numbers for the nucleotide sequence data reported in this paper are Z28387 (Hc. salifodinae BIp DSM 8989T), AJ238897 (strain Br3), AJ131458 (strain BG2/2), AJ245422 and AJ245423 (strain N1), AJ245424 and AJ245425 (strain H2). Accession numbers for other 16S rRNA sequences used for comparisons in this study have been reported previously (McGenity et al., 1998 R26 ).
The authors have previously isolated a novel extremely halophilic archaeon, Halococcus salifodinae BIp, from Austrian rock salt deposited about 250 million years ago. In this study they compared strain BIp with two other halococci isolated independently from geographically distant salt deposits of similar age, and with two recent isolates (N1 and H2) from the same site as strain Blp. Strain BG2/2 was from a salt mine in Germany and strain Br3 from a halite deposit in England; both resembled Hc. salifodinae BIp in cellular and colonial morphology. Strains BIp, BG2/2 and Br3 had identical 16S rRNA sequences, very similar whole-cell protein patterns, which were different from those of other halococci, similar G+C contents and identical sequences in a 108-base insertion in their 5S rRNA gene. Other similarities included composition and relative abundances of polar lipids, antibiotic susceptibility, enzymic activities and Fourier-transform infrared spectra. Strains N1 and H2 showed similar morphology, whole-cell protein patterns and biochemical characteristics as strains BIp, Br3 and BG2/2. Their partial 16S rRNA sequences (682 and 641 bases, respectively) were indistinguishable from those of strains BIp, Br3 and BG2/2. Therefore strains N1 and H2 can be considered as reisolates of Hc. salifodinae which were obtained 8 years after the first samples were taken from that mine. The results presented suggest that viable halophilic archaea, which belong to the same species, occur in widely separated evaporite locations of similar geological age, and support the notion that these halophilic isolates from subterranean salt deposits may be the remnants of populations which inhabited ancient hypersaline seas.
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- Genetics And Molecular Biology
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AUD4, a new amplifiable element from Streptomyces lividans
More LessThe GenBank accession number for the sequence reported in this paper is AF072709.
After transformation of the Streptomyces lividans chloramphenicol-sensitive, arginine-auxotrophic mutant strain AJ100 with a derivative of plasmid SCP2, some of the regenerated protoplasts contained an 8·2 kb DNA sequence amplified to several hundred copies per chromosome. The corresponding non-amplified sequence, called AUD4, was isolated from a λ phage genomic library of S. lividans 1326. Two cytosine residues were the only directly repeated nucleotides at the ends of the element, indicating that AUD4 is a class I amplifiable sequence. The element mapped in the AseI-D fragment of the S. lividans chromosome, where other class I amplifications have been described. The complete element was sequenced and 10 ORFs were identified. Some of the deduced proteins are highly conserved in other organisms but a putative function could be attributed to only a few of them. Duplication of AUD4 by integration of an Escherichia coli plasmid carrying various parts of AUD4 and a thiostrepton-resistance gene in S. lividans AJ100, ZX7 or TK64 induced amplification of the integrated plasmid, AUD4 or both at high frequency.
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Sequences and evolutionary analyses of eukaryotic-type protein kinases from Streptomyces coelicolor A3(2)
More LessThe GenBank accession numbers for the sequences determined in this work are AB016932, AB018799, AB019394 and AB021679.
Four eukaryotic-type protein serine/threonine kinases from Streptomyces coelicolor A3(2) were cloned and sequenced. To explore evolutionary relationships between these and other protein kinases, the distribution of protein serine/threonine kinase genes in prokaryotes was examined with the tfasta program. Genes of this type were detected in only a few species of prokaryotes and their distribution was uneven; Streptomyces, Mycobacterium, Synechocystis and Myxococcus each contained more than three such genes. Homology analyses by gap and Rdf2 programs suggested that some kinases from one species were closely related, whilst others were only remotely related. This was confirmed by examining phylogenetic trees constructed by the neighbour-joining and other methods. For each species, analysis of the coding regions indicated that the G+C content of protein kinase genes was similar to that of other genes. Considered with the fact that in phylogenetic trees the amino acid sequences of STPK from Aquifex aeolicus and some other eukaryotic-type protein kinases in prokaryotes form a cluster with protein kinases from eukaryotes, this suggests that the eukaryotic-type protein kinases were present originally in both prokaryotes and eukaryotes, but that most of these genes have been lost during the evolutionary process in prokaryotes because they are not needed. This conclusion is supported by the observation that the prokaryotes retaining several of these kinases undergo complicated morphological and/or biochemical differentiation.
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Family 19 chitinases of Streptomyces species: characterization and distribution
The GenBank accession numbers for the sequences determined in this work are AB031745–AB031757 inclusive.
Chitinase C from Streptomyces griseus HUT6037, described in 1997, is the first family 19 chitinase found in an organism other than higher plants. In this study, some properties of chitinase C were compared with those of family 18 bacterial chitinases, and the distribution of family 19 chitinases in Streptomyces species was investigated. The specific hydrolysing activity of chitinase C against soluble and insoluble chitinous substrates was markedly higher than those of bacterial family 18 chitinases. Chitinase C exhibited marked antifungal activity, whereas the other bacterial chitinases examined had no antifungal activity. Chitinase C was insensitive to allosamidin, whereas the family 18 bacterial chitinases were sensitive. Taking advantage of this insensitivity to allosamidin, a search was made for family 19 chitinases in various Streptomyces species. Chitinases insensitive to allosamidin were detected in the culture supernatants of all tested Streptomyces species. Southern hybridization analysis using a labelled DNA fragment corresponding to the catalytic domain of chitinase C strongly suggested that these species have genes similar to the chiC gene of S. griseus HUT6037. DNA fragments corresponding to the major part of the catalytic domains were amplified by PCR. The amplified fragments encoded amino acid sequences very similar to that of the corresponding region of chitinase C. Therefore, it was concluded that Streptomyces species generally possess family 19 chitinases which are very similar to chitinase C. Comparison of their amino acid sequences with those of plant family 19 chitinases revealed that Streptomyces family 19 chitinases are class IV type in terms of the presence and positions of deletions of amino acid sequences which are characteristic of plant class IV chitinases.
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Intermediates of rifamycin polyketide synthase produced by an Amycolatopsis mediterranei mutant with inactivated rifF gene
Rifamycin B biosynthesis in Amycolatopsis mediterranei N/813 was inactivated by introducing a small deletion in the rifF gene situated directly downstream of the rifamycin polyketide synthase (PKS) gene cluster. The corresponding mutant strain produced a series of linear intermediates of rifamycin B biosynthesis that are most probably generated by obstruction of the normal release of the end product of the rifamycin PKS. This result provides evidence that the rifF gene product catalyses the release of the completed linear polyketide from module 10 of the PKS and the intramolecular macrocyclic ring closure by formation of an amide bond, as indicated by sequence similarity of this protein to amide synthases. The chemical structures of the new rifamycin polyketide synthase intermediates released from modules 4 to 10 were determined by spectroscopic methods (UV, IR, NMR and MS) and gave insight into the reaction steps of rifamycin ansa chain biosynthesis and the timing of the formation of the naphthoquinone ring. The intermediates released from modules 6 and 8 were isolated as lactones formed by the terminal carboxyl group; proton NMR double resonance and ROESY(rotated frame nuclear Overhauser enhancement spectroscopy) experiments enabled the deduction of the relative configurations in the linear chain which correspond to the known absolute stereochemistry of rifamycin B.
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Analysis of genes involved in nitrate reduction in Clostridium perfringens
The GenBank accession number for the sequence reported in this paper is AB017192.
We have conducted the genetic analysis of fermentative nitrate reduction in Clostridium perfringens, a strict anaerobic bacterium. Nitrate reductase (NarA) was purified from the cytoplasmic fraction of the organism. Using a degenerate primer designed from its N- terminal amino acid sequence, a 9·5 kb fragment containing seven ORFs was cloned. The molecular mass and N-terminal amino acid sequence predicted from the nucleotide sequence of ORF 4 coincided with those determined for the purified NarA, indicating that ORF 4 corresponds to a narA gene. ORFs 5 and 6 encode a 15·4 kDa ferredoxin-like protein containing four iron–sulfur clusters and a 45 kDa protein homologous to NADH oxidase, respectively. Analyses involving primer extension and Northern blotting revealed that these three ORFs are transcribed as a polycistronic message. The ORF 5- and ORF 6-encoded proteins were shown by immunoblotting to be synthesized by cells grown in the presence of nitrate. Thus, these two proteins are likely to function as electron-transfer components in nitrate reduction in C. perfringens. The 9·5 kb fragment and a downstream region of 6·1 kb do not contain any genes involved in nitrate uptake or nitrite reduction. Instead, all 5 ORFs downstream of ORF 6 are homologous to genes reported for molybdopterin biosynthesis, unlike the genomic organization already determined for the respiratory and assimilatory nitrate-reduction systems. The evolutionary relationships between these two nitrate- reduction systems and the fermentative one based on the results of comparative genetic analysis are discussed.
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The Hsp90 of Candida albicans can confer Hsp90 functions in Saccharomyces cerevisiae: a potential model for the processes that generate immunogenic fragments of this molecular chaperone in C. albicans infections
During infections with a number of important eukaryotic pathogens the Hsp90 molecular chaperone of the pathogen is recognized as an immunodominant antigen by the host immune system. Yeast molecular genetics should allow study of the extent of sequence variation within conserved immunodominant epitopes on pathogen Hsp90s that is compatible with essential Hsp90 functions, as well as the processes that generate antigenic subfragments of these Hsp90s. The Hsp90 of the fungal pathogen Candida albicans was shown in this study to provide both essential and nonessential (pheromone signalling and mammalian steroid receptor activation) Hsp90 functions in Saccharomyces cerevisiae cells. Much of the C. albicans Hsp90 expressed in respiratory S. cerevisiae cells was shown to undergo a partial degradation in vivo, a degradation that closely resembles that of the native Hsp82 (one isoform of the homologous Hsp90) in S. cerevisiae. Allowing for the differences in the length of the charged linker region between the N- and C-terminal domains of C. albicans Hsp90 and S. cerevisiae Hsp82, these two proteins expressed in S. cerevisiae appear to give the same major degradation products. These Hsp90 fragments are similar to the products of incomplete Hsp90 degradation found in C. albicans cultures.
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The PE-PGRS glycine-rich proteins of Mycobacterium tuberculosis : a new family of fibronectin-binding proteins?
The GenBank accession number for the sequence reported in this paper is AF071081.
A clone was isolated by screening of a cosmid library of Mycobacterium tuberculosis with an oligonucleotide designed from the N-terminal sequence of a previously reported proline-rich protein. Characterization of the 4481 bp insert showed the presence of polymorphic CG-repetitive sequences (PGRSs) with an ORF of 2·7 kb, encoding a 81·3 kDa protein (PE- PGRS81). Southern blot analysis and blast-p searches revealed several homologous sequences in the genome of M. tuberculosis. The deduced amino acid sequence was highly similar to a stretch of about 98 residues in the N-terminus present in several members of the PE-PGRS family available in the GenBank database, including 100% identity with the partial amino acid sequence of the potential protein encoded by orf3′ as well as with the Rv0278c sequence. A neighbour-joining analysis of the 99 PE-PGRS sequences available in the database indicated that PE-PGRS81 is included in a group where its closest relatives are the sequences orf3′, Rv0278c, Rv0279c, Rv1759c, Rv3652 and Rv0747. Probing with the complete coding regions of PE- PGRS81 and Rv1759c in Southern blot assays, on samples of genomic DNA from M. tuberculosis H37Rv, Mycobacterium bovis BCG and M. tuberculosis clinical isolates, showed a complex hybridization pattern for all strains. This shows the existence of intrastrain PGRS variability as reported for other PGRS members. In contrast, probing with the short conserved N-terminal region of Rv1759c reduced the hybridization to a single band. This marker allowed identification of M. tuberculosis clinical strains that lack Rv1759c. A recombinant C-terminal fragment of Rv1759c showed fibronectin-binding properties and was recognized by sera from patients infected with M. tuberculosis, suggesting that at least this member of thePE-PGRS is expressed in tuberculosis infection.
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Production of mutants in amino acid biosynthesis genes of Mycobacterium tuberculosis by homologous recombination
More LessThe ability to generate mutants of Mycobacterium tuberculosis will be important if we are to understand the biology of this major pathogen. However, allelic replacement methods have only recently achieved success. We have developed a reproducible method for generating defined mutants of M. tuberculosis using homologous recombination. The transforming DNA was used following pre-treatment either with UV light or alkali denaturation in order to stimulate homologous recombination and abolish illegitimate recombination. Suicide vectors carrying one of nine amino acid biosynthesis genes were electroporated into M. tuberculosis, and homologous recombinants were obtained in all nine genes; eight resulted from single-crossover events (SCOs) and one from a double-crossover event (DCO) (in the metB gene). The remaining colonies were spontaneous hygromycin-resistant mutants; no products of illegitimate recombination were observed. To more efficiently distinguish spontaneous mutants, the lacZ gene was cloned into five vectors (two containing genes not previously tested), and the transformations were repeated. SCO mutants were identified by screening for blue colonies on indicator plates. White transformants were tested for auxotrophy and trpD, hisD and proC auxotrophic mutants were obtained. Only blue SCOs were obtained for argF and glnE. Thus, using this methodology we have obtained homologous recombination in 11 genes, and DCOs in 4 genes, showing that it is possible to generate targeted mutants in a reproducible way.
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Functional analysis of genes responsible for the synthesis of the B-band O antigen of Pseudomonas aeruginosa serotype O6 lipopolysaccharide
More LessThe GenBank accession number for the sequence reported in this paper is AF035937.
This study reports the organization of the wbp gene cluster and characterization of a number of genes that are essential for B-band O antigen biosynthesis in the clinically prevalent Pseudomonas aeruginosa serotype O6. Twelve genes were identified that share homology with other LPS and polysaccharide biosynthetic genes. This cluster contains homologues of wzx (encoding the O antigen flippase/translocase) and wzz (which modulates O antigen chain length distribution) genes, typical of a wzy- dependent pathway. However, a complete wzy gene (encoding the O-polymerase) was not found within the cluster. Four biosynthetic genes, wbpO, wbpP, wbpV and wbpM, and four putative glycosyltransferase genes, wbpR, wbpT , wbpU and wbpL, were identified in the cluster. To characterize their roles in LPS biosynthesis, null mutants of wbpO, wbpP, wbpV, wbpL and wbpM were generated using a gene-replacement strategy. Mutations in each of these genes caused deficiency in B-band synthesis. The wbpL mutant was deficient in both A-band and B-band LPS. WbpLO6 is a bi-functional enzyme which could initiate B-band synthesis through the addition of QuiNAc to undecaprenol phosphate, and A-band synthesis by transferring either a GalNAc or a GlcNAc residue. Another approach used to assign function to the wbp O6 genes was by complementation analysis. Two genes from Salmonella typhi, wcdA and wcdB, responsible for the synthesis of a homopolymer of GalNAcA called Vi antigen were used in complementation experiments to verify the functions of wbpO and wbpP. wcdA and wcdB restored B-band synthesis in wbpO and wbpP mutants respectively, implying that wbpO and wbpP are involved in UDP-GalNAcA synthesis. Although wbpV has homology to wbpK of the serotype O5 B-band LPS synthesis cluster, complementation analysis using the respective null mutants showed that the genes are not interchangeable. A knockout mutation of wbpN (located downstream of wbpM) did not abrogate LPS synthesis in either O5 or O6; therefore, it has been renamed orf48.5. These results establish the organization of genes involved in P. aeruginosa B-band O antigen synthesis and provide the evidence to assign functions to a number of LPS biosynthetic genes.
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Representational difference analysis of cDNA for the detection of differential gene expression in bacteria: development using a model of iron-regulated gene expression in Neisseria meningitidis
More LessRepresentational difference analysis of cDNA (cDNA RDA) provides a powerful technique for the identification of specific differences between two mRNA populations. The method has previously been used to analyse differential gene expression in eukaryotes, but until now has not been successfully applied to prokaryotes. A strain of Neisseria meningitidis with a deletion of the iron-regulated lactoferrin-binding protein A (lbpA) gene, grown under iron- replete conditions, and the isogenic parent strain, grown under iron limitation, were used as a model for developing cDNA RDA for use with bacteria. In this system, the technique should specifically detect the differential expression of the lbpA gene in the parent strain, along with other genes whose expression is switched on (or up- regulated) under iron-deficient conditions. Since cDNA RDA requires high-quality, representative mRNA, a variety of methods for the isolation of RNA were evaluated. A triisopropylnaphthalene sulphonic acid/p-aminosalicylic acid-based technique was found to give the best results. cDNA was prepared from total RNA isolated from the two N. meningitidis strains and subjected to an adapted cDNA RDA procedure. The method resulted in the amplification of five major PCR products, which included fragments of the lbpA gene and the iron-regulated RTX-like toxin gene (frpC), thus validating the technique for use with bacteria.
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- Genomics
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Novel phosphotransferase system genes revealed by genome analysis – the complete complement of PTS proteins encoded within the genome of Bacillus subtilis
Bacillus subtilis can utilize several sugars as single sources of carbon and energy. Many of these sugars are transported and concomitantly phosphorylated by the phosphoenolpyruvate:sugar phosphotransferase system (PTS). In addition to its role in sugar uptake, the PTS is one of the major signal transduction systems in B. subtilis. In this study, an analysis of the complete set of PTS proteins encoded within the B. subtilis genome is presented. Fifteen sugar-specific PTS permeases were found to be present and the functions of novel PTS permeases were studied based on homology to previously characterized permeases, analysis of the structure of the gene clusters in which the permease encoding genes are located and biochemical analysis of relevant mutants. Members of the glucose, sucrose, lactose, mannose and fructose/mannitol families of PTS permeases were identified. Interestingly, nine pairs of IIB and IIC domains belonging to the glucose and sucrose permease families are present in B. subtilis; by contrast only five Enzyme IIA Glc-like proteins or domains are encoded within the B. subtilis genome. Consequently, some of the EIIAGlc-like proteins must function in phosphoryl transfer to more than one IIB domain of the glucose and sucrose families. In addition, 13 PTS- associated proteins are encoded within the B. subtilis genome. These proteins include metabolic enzymes, a bifunctional protein kinase/phosphatase, a transcriptional cofactor and transcriptional regulators that are involved in PTS-dependent signal transduction. The PTS proteins and the auxiliary PTS proteins represent a highly integrated network that catalyses and simultaneously modulates carbohydrate utilization in this bacterium.
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Absence in Helicobacter pylori of an uptake sequence for enhancing uptake of homospecific DNA during transformation
More LessUptake sequences are abundant sequence motifs, often located downstream of ORFs, that are used to facilitate the within-species horizontal transfer of DNA. A frequent word analysis of the complete genome sequence of Helicobacter pylori strain 26685 was performed to search for and determine the identity of an uptake sequence in this species. The results demonstrated that Hel. pylori does not possess an uptake sequence. This is the first naturally transformable Gram-negative species shown to lack such a transformation- targeting system.
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- Pathogenicity And Medical Microbiology
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Intracellular survival of Burkholderia cepacia complex isolates in the presence of macrophage cell activation
More LessStrains of the Burkholderia cepacia complex have emerged as a serious threat to patients with cystic fibrosis due to their ability to infect the lung and cause, in some patients, a necrotizing pneumonia that is often lethal. It has recently been shown that several strains of the B. cepacia complex can escape intracellular killing by free-living amoebae following phagocytosis. In this work, the ability of two B. cepacia complex strains to resist killing by macrophages was explored. Using fluorescence microscopy, electron microscopy and a modified version of the gentamicin-protection assay, we demonstrate that B. cepacia CEP021 (genomovar VI), and Burkholderia vietnamiensis (previously B. cepacia genomovar V) CEP040 can survive in PU5- 1.8 murine macrophages for a period of at least 5 d without significant bacterial replication. Furthermore, bacterial entry into macrophages stimulated production of tumour necrosis factor and primed them to release toxic oxygen radicals following treatment with phorbol myristoyl acetate. These effects were probably caused by bacterial LPS, as they were blocked by polymyxin B. Infected macrophages primed with interferon gamma produced less nitric oxide than interferon-gamma- primed uninfected cells. We propose that the ability of B. cepacia to resist intracellular killing by phagocytic cells may play a role in the pathogenesis of cystic fibrosis lung infection. Our data are consistent with a model where repeated cycles of phagocytosis and cellular activation without bacterial killing may promote a deleterious inflammatory response causing tissue destruction and decay of lung function.
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Bacterial fibronectin-binding proteins and endothelial cell surface fibronectin mediate adherence of Staphylococcus aureus to resting human endothelial cells
More LessAdhesion of Staphylococcus aureus to human endothelial cells is implicated in the pathogenesis of invasive staphylococcal disease. The adhesion to endothelial cells of isogenic mutants defective in defined surface structures was studied. Three strains of S. aureus defective in fibronectin-binding proteins FnBPA and FnBPB showed reduced adhesion. This was fully restored by complementation of a FnBPA− FnBPB− mutant derived from strain 8325-4 with a multicopy plasmid encoding FnBPA or FnBPB. Adhesion of mutants defective in other surface structures was unaffected. Anti-fibronectin antibodies blocked adhesion of 8325-4 to endothelial cells, while adhesion of strains 8325-4, P1 and five clinical isolates was inhibited by the recombinant form of the binding domain of FnBPB (rFNBD) from Streptococcus dysgalactiae . Adherence of bacterial aggregates resulting from the presence of purified fibrinogen was also inhibited by rFNBD protein. Three strains of S. aureus defective in FnBPA and FnBPB were not internalized by endothelial cells. S. aureus FnBPs mediate adhesion to human endothelial cells and are required for subsequent internalization, interactions of potential relevance to pathogenesis and treatment.
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Volume 11 (1954)
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Volume 10 (1954)
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Volume 9 (1953)
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Volume 8 (1953)
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Volume 7 (1952)
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Volume 6 (1952)
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Volume 5 (1951)
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Volume 4 (1950)
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Volume 3 (1949)
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Volume 2 (1948)
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Volume 1 (1947)