Summary: The prs gene, encoding phosphoribosylpyrophosphate synthetase, is preceded by a leader, which is 302 bp long in Escherichia coli and 417 bp in Salmonella typhimurium. A potential open reading frame (ORF) extends across the prs promoter and into the leader. The region between the prs coding region and an upstream gene (hemA) in E. coli and S. typhimurium was cloned, sequenced and shown to encode two ORFs of unknown function. ORF 1 encodes a 23 kDa protein and ORF 2 a 31 kDa protein, as observed by denaturing PAGE of extracts of cells bearing plasmids encoding the ORFs. Both ORFs are transcribed in the same direction as the prs gene with ORF 2 extending into the prs leader. Northern blot analysis showed that the prs message in E. coli was on 1.3 and 2.7 kb transcripts. The shorter transcript encoded the prs gene only, while the longer transcript also encoded the two ORFs. Thus, the prs gene is transcribed from two promoters, the first promoter (P1) originating upstream of ORF 1, and expressing the prs gene in a tricistronic operon and a second promoter (P2), located within the ORF 2 coding frame, which transcribes the prs gene only. The transcripts encoding prs only were 20 times as abundant as the tricistronic transcripts under all conditions examined. This was the case whether cells containing plasmid-encoded or only chromosomally encoded copies of the hemA-prs region were probed for these transcripts. Derepression of the prs gene upon pyrimidine starvation was shown to be due to an increase in the amount of message originating from the promoter P2.
Summary: Lipase of Staphylococcus epidermidis 9 was purified from culture supernatant fluid. Two polypeptides (51 and 43 kDa) were detected by SDS-PAGE, of which the 43 kDa polypeptide reacted with anti-lipase serum. The S. epidermidis 9 lipase gene (gehC) was cloned in Escherichia coli and localized to a 2.1 kb sequence by subcloning and transposon mutagenesis. The nucleotide sequence of gehC (2064 nucleotides) was determined and the predicted amino acid sequence of the encoded lipase (77 kDa) identified. A 97 kDa lipase was detected in extracts of E. coli harbouring gehC and in post-exponential-phase culture supernatant fluids of S. epidermidis 9. Data presented indicate that the lipase behaves anomalously during SDS-PAGE and that a pro-lipase is proteolytically processed in cultures of S. epidermidis 9 during growth.
Summary: Sexual cell fusion occurs between NC4 and HM1, heterothallic strains of Dictyostelium discoideum. Several cell surface proteins relevant to the process have been identified. One of them, gp138, exists in fusion-competent cells of both NC4 and HM1, and is considered to be more concerned with membrane fusion than gamete recognition. In this study, we raised monoclonal antibodies against gp138 and examined gp138 distribution among strains and species of cellular slime moulds to confirm its importance in sexual cell fusion. All heterothallic and bisexual D. discoideum strains examined were found to possess gp138, while asexual and homothallic strains lacked it. The anti-gp138 monoclonal antibody detected several distinct proteins in homothallic strains and one in an asexual strain. Some of the former proteins appeared together with the increase in binucleated cells. Cells of Dictyostelium mucoroides and Polysphondylium pallidum did not possess proteins reactive to the monoclonal antibody. These results indicate that gp138 is common among, but restricted to, cross-matable strains of D. discoideum. Our results also support previously published molecular phylogenetic studies which suggest that homothallic and asexual strains of D. discoideum are remote from other strains of D. discoideum but are less distantly related to them than other species are.
Summary: Actinomycin D-resistant RNA synthesis was detected in the cellular (VM) fraction which contains large vesicles plus mitochondria from Agrocybe aegerita. It involved the RNAase-resistant complex of naked (unencapsidated) double-stranded RNAs (dsRNAs). The RNA polymerase assay showed [α-32P]UTP incorporation in dsRNAs of a size corresponding to the previously described naked M-dsRNAs and in single-stranded RNAs of related size, which are assumed to act as intermediaries in the replicative cycle of the dsRNA molecules. Moreover, the incorporation of ribonucleotides into large mitochondrial dsDNA fragments was detected in the dsRNA-containing strain. This result favours a mitochondrial location for the naked dsRNAs and their associated polymerizing enzyme(s). No replication of the encapsidated large L-dsRNA viral genome was detected in the VM fraction, supporting the hypothesis that the two types of dsRNAs observed in this A. aegerita strain are independent entities.
Summary: Acinetobacter calcoaceticus BD413 develops competence for natural transformation immediately after the start of the exponential growth-phase and remains competent up to a few hours into the stationary phase, after which competence gradually declines. The transformation frequencies obtained strongly depend on the kind of transforming DNA and the incubation time with DNA. Up to 25% of the cells in a culture can be transformed. DNA uptake in Acinetobacter does not display sequence specificity, is Mg2+-, Mn2+- or Ca2+-dependent and is uncoupler sensitive. The transforming DNA enters the cells in single-stranded form. These properties constitute a unique combination, not previously observed in other bacteria, and make A. calcoaceticus ideally suited for detailed studies of the bioenergetics of DNA translocation.
Summary: The Clostridium thermocellum cell gene, coding for endoglucanase I (Cell), consists of an open reading frame (ORF) of 2640 nucleotides and codes for a protein of M r 98531. The ORF was confirmed as cell by comparing the N-terminal sequence of purified recombinant Cell with that deduced from the nucleotide sequence. Cell hydrolysed lichenan and carboxymethylcellulose, but was principally active against barley β-glucan. It exhibited significant sequence identity with subfamily E2 endoglucanases, and by analogy with others in this group contains a catalytic domain of around 500 residues located in the N-terminal half of the protein. The C-terminal region of Cell was highly homologous with the cellulose-binding domain of the non-catalytic cellulosome subunit, S1. A repeated segment, previously shown to be highly conserved in xylanase Z and in other endoglucanases from C. thermocellum, was absent from Cell. Antiserum raised against purified recombinant Cell cross-reacted with proteins contained in the cellulosomes of two strains of C. thermocellum, suggesting that Cell is either a component of the cellulosome or is homologous to other cellulosome proteins. A second gene, located upstream of cell, consisted of an ORF of 1671 nucleotides, coding for a protein of M r 61042. Based on its homology with the Escherichia coli tar gene product, the polypeptide encoded by the second gene is tentatively identified as a sensory transducer.
Summary: The DNA sequence of the gene encoding the early and specific immunogenic protein P36 of Mycoplasma hyopneumoniae has been determined. Comparison of the DNA sequence and the deduced amino acid sequence of P36 with known genes and proteins in data banks indicated that P36 is a L-lactate dehydrogenase (LDH) (EC 126.96.36.199). Biochemical analysis of protein P36 expressed from the cloned gene in Escherichia coli confirmed that P36 has L-lactate dehydrogenase activity. Protein P36 of M. hyopneumoniae therefore is termed LDH and its gene Idh. M. hyopneumoniae LDH was shown to contain the typical domains of LDH of other bacterial species. Immunologically however, we have shown that polyclonal antibodies against M. hyopneumoniae LDH do not cross-react with related LDH and show high specificity for M. hyopneumoniae. The Idh gene is preceded by several typical −10 sequences found in promoters of prokaryotes, but lacks the −35 sequence. Sequences rich in A + T, however, precede the −10 boxes, suggesting that factors involved in transcription initiation and their regulation may be different in M. hyopneumoniae compared to other bacterial species, but the putative ribosome binding site seems to be conserved.
Summary: A nucleotide sequence encoding an exo-β-(1,3)-glucanase was cloned from a library of genomic DNA of Candida albicans ATCC 10261. The sequenced gene encodes a protein of 438 amino acid residues. The amino terminal and an internal peptide sequence of the enzyme matched with deduced sequences within the cloned gene. Analysis of the sequence indicated that the nascent protein is processed during secretion by the signal peptidase and a Kex2-like proteinase, yielding a predicted mature enzyme of 400 residues. There is 58% identity and 85% similarity between the amino acid sequences of this exoglucanase and the homologous enzyme of Saccharomyces cerevisiae. An antiserum to the purified exoglucanase cross-reacted with the S. cerevisiae exoglucanase and a similar protein secreted by other C. albicans strains and Candida species. There are no sites for N-linked glycosylation in the sequence and this is consistent with the carbohydrate content of the secreted enzyme. Putative upstream promoter elements are associated with the gene. Southern analysis of the gene indicated that it was present at one copy per genome and that the diploid genome of C. albicans ATCC 10261 is heterozygous at this locus for a Bg/II RFLP. A 2.5 kb mRNA transcript was detected by Northern analysis and gene expression, as monitored by Northern and Western blots, reflected the growth rates of the cultures.
Summary: Candida parapsilosis secretes an inducible acid protease (ACP) when cultivated in the presence of bovine serum albumin as the sole nitrogen source. In order to clone the ACP gene (ACP) of C. parapsilosis, a genomic library was screened with C. tropicalis ACP as the probe. Two different ORFs, ACPR and ACPL, were found to hybridize with the C. tropicalis ACP. ACPR contained a DNA sequence in agreement with the N-terminal amino acid sequence of C. parapsilosis ACP isolated from culture supernatants. ACPR was shown to be expressed and functional in a C. tropicalis acid protease mutant (acp) and with SDS-PAGE the protein product showed the same mobility as the ACP secreted by C. parapsilosis. These results imply that ACPR encodes the C. parapsilosis ACP. The deduced amino acid sequence of ACPR is similar to the amino acid sequence of proteases of the pepsin family. As in the case of the C. tropicalis and C. albicans ACP, the 5” extremity of ACPR revealed a propeptide containing two Lys-Arg amino acid pairs that have been identified as peptidase processing sites in several yeast-secreted peptides and protein precursors. As judged from the deduced amino acid sequences, the ACPL product would be similar to that of ACPR; however, a protein corresponding to ACPL was not found in supernatants from C. parapsilosis liquid cultures. In addition, ACPL did not complement the C. tropicalis acp mutant. We conclude that ACPL is a pseudogene or serves an as yet unidentified function.
Summary: Expression in the yeast Saccharomyces cerevisiae of the intact nprE gene of Bacillus subtilis, which encodes the pre-pro-NprE neutral protease precursor, resulted in intracellular accumulation of unprocessed precursor without detectable secretion or processing of the expressed gene product. When sequences specifying the signal peptide of yeast invertase were fused upstream of sequences encoding the mature NprE enzyme, nprE gene products were secreted into the culture medium. The secreted protein products were, however, highly glycosylated and biologically inactive.
Summary: The Bacillus subtilis glpPFKD region contains genes essential for growth on glycerol or glycerol 3-phosphate (G3P). The nucleotide sequence of glpP encoding a regulatory protein and the previously unidentified glpF encoding the glycerol uptake facilitator was determined. glpF is located immediately upstream of glpK and the two genes were shown to constitute one operon which is transcribed separately from glpP. A σA-type promoter and the transcriptional start point for glpFK were identified. In the 5” untranslated leader sequence (UTL) of glpFK mRNA a conserved inverted repeat is found. The repeat is believed to be involved in the control of expression of glpFK by termination/antitermination of transcription, a control mechanism previously suggested for the regulation of glpD encoding G3P dehydrogenase. Expression of glpFK and glpD requires the inducer G3P and the glpP gene product. A 2.9 kb B. subtilis chromosomal DNA fragment containing the glpP open reading frame was cloned to give plasmid pLUM7. pLUM7 contains a functional glpP gene as shown by its ability to complement various glpP mutants. Immediately upstream of glpP an open reading frame is found (ORF1). Disrupting ORF1 by plasmid integration in the B. subtilis chromosome does not affect the ability to grow on glycerol as sole carbon and energy source. With the present report all B. subtilis glp genes located at 75° on the chromosomal map have been identified.
Summary: The sequence of a 4.4 kbp region of DNA from Bacillus subtilis 168, lying between sporulation genes spoVD and spoVE, has been determined as part of the B. subtilis genomic sequencing programme. The region contains three genes with high sequence similarity to the murE, mraY and murD genes of Escherichia coli. The products of these genes are likely to catalyse various steps in the formation of the precursors for peptidoglycan synthesis in B. subtilis. The regions at 133° on the standard genetic map of the B. subtilis chromosome, and in the 2 min region of the E. coli genetic map, are now shown to contain a large cluster of functionally related genes. Although the linear order of the genes in the cluster is conserved, three genes that are present in the E. coli chromosome, and which are likely to be essential for peptidoglycan synthesis in both organisms, are absent from this region of the B. subtilis chromosome. In general, the B. subtilis cluster differs from that of E. coli in having more extensive intergenic regions, with less potential for translational coupling.