Journal
FEMS MICROBIOLOGY LETTERS
Volume 295, Issue 2, Pages 177-186Publisher
OXFORD UNIV PRESS
DOI: 10.1111/j.1574-6968.2009.01589.x
Keywords
two-component regulatory system; DNA-protein interaction; transcriptional regulation; sigma(54); psychrophile
Categories
Funding
- MURST [PRIN 2003, FIRB 2001]
- PNR [Antartide 2004]
- Regione Campania [L.R. 05/03]
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Two-component systems are widespread in nature and constitute the most common mechanism of transmembrane signal transduction in bacteria. Recently, a functionally active two-component system consisting of malS and malR genes possibly involved in the expression of a C4-dicarboxylate transporter system (dctAB operon) was identified in the marine Antarctic bacterium Pseudoalteromonas haloplanktis TAC125. In this paper, we performed a functional analysis of the two-component system and demonstrated its involvement in the regulation of the expression of C4-dicarboxylate transporter genes. The expression of the C4-dicarboxylate transporter genes was induced by l-malate with the promoter element located upstream of the dctA gene being active only in the presence of the inducer. A sigma(54) promoter responsible for the l-malate dependent transcription regulation was identified and functionally characterized. The molecular mechanism involves an inverted repeat sequence located upstream the sigma(54) promoter that was shown to bind regulatory proteins only in the presence of l-malate. The protein factor responsible for the induction of the dctAB operon expression was eventually identified as the transcriptional regulatory protein MalR. MalR is the first transcriptional factor identified in P. haloplanktis TAC125 and one of the few transcriptional modulators reported so far in cold adapted bacteria.
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