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A conserved two-component signal transduction system controls the response to phosphate starvation in Bifidobacterium breve UCC2003.

Appl Environ Microbiol. 2012 May 25. [Epub ahead of print]

A conserved two-component signal transduction system controls the response to phosphate starvation in Bifidobacterium breve UCC2003.

Alvarez-Martin P*, Fern√°ndez M, O'Connell-Motherway M, O'Connell KJ, Sauvageot N, Fitzgerald GF, Macsharry J, Zomer A, van Sinderen D.

Alimentary Pharmabiotic Centre and Department of Microbiology, University College Cork; Cork, Ireland.

This work reports on the identification and molecular characterization of the two-component regulatory system (2CRS) PhoRP, which controls the response to phosphate (Pi) starvation in Bifidobacterium breve UCC2003. The response regulator PhoP was shown to bind to the promoter region of pstSCAB, specifying a predicted Pi transporter system, as well as that of phoU, which encodes a putative Pi-responsive regulatory protein. This interaction is assumed to cause transcriptional modulation under conditions of Pi limitation. Our data suggest that the phoRP genes are subject to positive auto-regulation, and together with pstSCAB and presumably phoU represent the complete regulon controlled by the phoRP-encoded 2CRS in B. breve UCC2003. Determination of the minimal PhoP binding region combined with bioinformatic analysis revealed the probable recognition sequence of PhoP, designated here as the PHO box, which together with phoRP is conserved among many high GC-content Gram+ bacteria. The importance of the PhoRP 2CRS in the response of B. breve to Pi starvation conditions was confirmed by analysis of a B. breve::phoP insertion mutant which exhibited decreased growth under phosphate-limiting conditions as compared to its parent strain UCC2003.

PMID: 22635988

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