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A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella.
BMC Microbiol. 2012 Oct 02; 12:224.BM

Abstract

BACKGROUND

Bacteria 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.

RESULTS

Here, 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.

CONCLUSIONS

We 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.

Authors+Show Affiliations

Department of Advanced Bioscience, Graduate School of Agriculture, Kinki University, Nakamachi, Nara, Japan. kato_a@nara.kindai.ac.jpNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23031642

Citation

Kato, Akinori, et al. "A Connecter-like Factor, CacA, Links RssB/RpoS and the CpxR/CpxA Two-component System in Salmonella." BMC Microbiology, vol. 12, 2012, p. 224.
Kato A, Hayashi H, Nomura W, et al. A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella. BMC Microbiol. 2012;12:224.
Kato, A., Hayashi, H., Nomura, W., Emori, H., Hagihara, K., & Utsumi, R. (2012). A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella. BMC Microbiology, 12, 224. https://doi.org/10.1186/1471-2180-12-224
Kato A, et al. A Connecter-like Factor, CacA, Links RssB/RpoS and the CpxR/CpxA Two-component System in Salmonella. BMC Microbiol. 2012 Oct 2;12:224. PubMed PMID: 23031642.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A connecter-like factor, CacA, links RssB/RpoS and the CpxR/CpxA two-component system in Salmonella. AU - Kato,Akinori, AU - Hayashi,Hironori, AU - Nomura,Wataru, AU - Emori,Haruka, AU - Hagihara,Kei, AU - Utsumi,Ryutaro, Y1 - 2012/10/02/ PY - 2012/07/11/received PY - 2012/09/21/accepted PY - 2012/10/4/entrez PY - 2012/10/4/pubmed PY - 2013/5/15/medline SP - 224 EP - 224 JF - BMC microbiology JO - BMC Microbiol VL - 12 N2 - BACKGROUND: Bacteria 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. RESULTS: Here, 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. CONCLUSIONS: We 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. SN - 1471-2180 UR - https://www.unboundmedicine.com/medline/citation/23031642/A_connecter_like_factor_CacA_links_RssB/RpoS_and_the_CpxR/CpxA_two_component_system_in_Salmonella_ L2 - https://bmcmicrobiol.biomedcentral.com/articles/10.1186/1471-2180-12-224 DB - PRIME DP - Unbound Medicine ER -