f Acid tolerance in Rhizobium meliloti strain WSM419 involves a two-component sensor-regulator system
- Authors: Ravi P. Tiwari, Wayne G. Reeve, Michael J. Dilworth, Andrew R. Glenn2
- 2Author for correspondence: Andrew R. Glenn. Tel: +61 9 360 2231. Tel: +61 9 360 6303. e-mail: firstname.lastname@example.org
- Microbiology, July 1996 142: 1693-1704, doi: 10.1099/13500872-142-7-1693
- Subject: Physiology And Growth
- Published Online:
An acid-sensitive mutant TG5-46, derived from Rhizobium meliloti WSM419 by Tn5 mutagenesis, fails to grow below pH 6.0 whereas the parent strain grows at pH 5.7. The DNA sequence of a 2.2 kb rhizobial DNA region flanking Tn5 in TG5-46 contains two open reading frames, ORF1 (designated actS) and ORF2 (designated actR), having high similarity to the sensor-regulator pairs of the two-component systems involved in signal transduction in prokaryotes. Insertion of an omega interposon into actS in R. meliloti WSM419 resulted in an acid-sensitive phenotype. A DNA fragment from the wild-type complemented the acid-sensitive phenotype of RT295 (ActS-) and TG5-46 (ActR-), while fragments containing only actR or actS complemented TG5-46 and RT295, respectively. The presence of multiple copies of actR complementes not only TG5-46 but also RT295. Cloning DNA upstream from actR and actS into a broad-host-range lacZ expression vector and measuring β-galactosidase activities showed that both genes are constitutively expressed regardless of the external pH. Genomic DNA from all strains of R. meliloti, but no other bacteria tested, hybridized with an actRS probe at high stringency. These data implicate a two-component sensor-regulator protein pair in acid tolerance in R. meliloti and suggest their involvement in pH sensing and/or response by these bacteria.
- Keyword(s): two-component sensor-regulator system, acid-tolerance genes, pH sensing, Rhizobium meliloti
© Society for General Microbiology 1996 | Published by the Microbiology Society
Article metrics loading...
Full text loading...
Author and Article Information
/content/journal/micro/10.1099/13500872-142-7-1693dcterms_title,dcterms_subject,pub_serialTitlepub_serialIdent:journal/micro AND -contentType:BlogPost64
/content/journal/micro/10.1099/13500872-142-7-1693dcterms_title,dcterms_subject-pub_serialIdent:journal/micro AND -contentType:BlogPost64
Figure data loading....