RcsA, an unstable positive regulator of capsular polysaccharide synthesis - PubMed (original) (raw)

Comparative Study

RcsA, an unstable positive regulator of capsular polysaccharide synthesis

V Stout et al. J Bacteriol. 1991 Mar.

Abstract

RcsA is an unstable positive regulator required for the synthesis of colanic acid capsular polysaccharide in Escherichia coli. Degradation of the RcsA protein in vivo depends on the ATP-dependent Lon protease. DNA sequence analysis of the rcsA gene reveals a single open reading frame for a 23,500-Da highly basic protein (pI = 9.9), consistent with the observed size of the purified subunit of RcsA. The DNA and protein sequences are highly homologous to the rcsA gene and protein from Klebsiella pneumoniae and other species. The carboxy-terminal region of RcsA contains a possible helix-turn-helix DNA-binding motif that resembles sequences found at the carboxy terminus of RcsB, another positive regulator of capsule synthesis, and in several other transcriptional regulators including members of the LuxR family. rcsA62, a mutation in rcsA that leads to increased capsule synthesis, encodes a protein designated RcsA*, which differs from wild-type RcsA only in the replacement of Met-145 by valine. The RcsA* protein is subject to Lon-dependent degradation. The stability of wild-type RcsA in vivo is increased by multicopy RcsB. Conversely, RcsA is degraded more rapidly in rcsB mutant hosts than in wild-type hosts. These results suggest that RcsA and RcsB interact in vivo and are consistent with genetic experiments that indicate an interaction between RcsA and RcsB. Based on these experiments, we propose a model for capsule regulation in which RcsA interacts directly with RcsB to promote transcription of the genes for capsule synthesis.

PubMed Disclaimer

Similar articles

Cited by

References

    1. J Bacteriol. 1984 Oct;160(1):184-91 - PubMed
    1. J Bacteriol. 1986 Jun;166(3):756-62 - PubMed
    1. Proc Natl Acad Sci U S A. 1986 Oct;83(20):7875-8 - PubMed
    1. J Bacteriol. 1986 Nov;168(2):619-23 - PubMed
    1. J Bacteriol. 1987 Mar;169(3):981-9 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources