A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella

BMC Microbiology

Research Article

Hironori Hayashi¹  Akinori Kato¹  Kei Hagihara¹  Haruka Emori¹  Ryutaro Utsumi¹  Wataru Nomura¹ 

[1] Department of Advanced Bioscience, Graduate School of Agriculture, Kinki University, 631–85053327-204, Nakamachi, Nara, Japan;

关键词: Two-component system;    Connector;    Network;    RssB;    RpoS;    CacA;    CpxR/CpxA;   

DOI  :  10.1186/1471-2180-12-224

 received in 2012-07-11, accepted in 2012-09-21,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundBacteria integrate numerous environmental stimuli when generating cellular responses. Increasing numbers of examples describe how one two-component system (TCS) responds to signals detected by the sensor of another TCS. However, the molecular mechanisms underlying this phenomenon remain poorly defined.ResultsHere, we report a connector-like factor that affects the activity of the CpxR/CpxA two-component system in Salmonella enterica serovar Typhimurium. We isolated a clone that induced the expression of a cpxP-lac gene fusion from a high-copy-number plasmid pool of random Salmonella genomic fragments. A 63-amino acid protein, CacA, was responsible for the CpxA/CpxR-dependent activation of the cpxP gene. The CpxR-activated genes cpxP and spy exhibited approximately 30% and 50% reductions in transcription, respectively, in a clean cacA deletion mutant strain in comparison to wild-type. From 33 response regulator (RR) deletion mutants, we identified that the RssB regulator represses cacA transcription. Substitution mutations in a conserved -10 region harboring the RNA polymerase recognition sequence, which is well conserved with a known RpoS -10 region consensus sequence, rendered the cacA promoter RpoS-independent. The CacA-mediated induction of cpxP transcription was affected in a trxA deletion mutant, which encodes thioredoxin 1, suggesting a role for cysteine thiol-disulfide exchange(s) in CacA-dependent Cpx activation.ConclusionsWe identified CacA as an activator of the CpxR/CpxA system in the plasmid clone. We propose that CacA may integrate the regulatory status of RssB/RpoS into the CpxR/CpxA system. Future investigations are necessary to thoroughly elucidate how CacA activates the CpxR/CpxA system.

【 授权许可】

CC BY   
© Kato et al.; licensee BioMed Central Ltd. 2012