Role of EctR as Transcriptional Regulator of Ectoine Biosynthesis Genes in Methylophaga thalassica

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I. I. Mustakhimov, A. S. Reshetnikov, D. N. Fedorov, V. N. Khmelenina^*, and Y. A. Trotsenko

Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142290 Pushchino, Moscow Region, Russia; fax: (495) 956-3370; E-mail: khmelenina@rambler.ru

^* To whom correspondence should be addressed.

Received March 12, 2012; Revision received March 27, 2012

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In the halophilic aerobic methylotrophic bacterium Methylophaga thalassica, the genes encoding the enzymes for biosynthesis of the osmoprotectant ectoine were shown to be located in operon ectABC-ask. Transcription of the ect-operon was started from the two promoters homologous to the σ⁷⁰-dependent promoter of Escherichia coli and regulated by protein EctR, whose encoding gene, ectR, is transcribed from three promoters. Genes homologous to ectR of methylotrophs were found in clusters of ectoine biosynthesis genes in some non-methylotrophic halophilic bacteria. EctR proteins of methylotrophic and heterotrophic halophiles belong to the MarR-family of transcriptional regulators but form a separate branch on the phylogenetic tree of the MarR proteins.

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KEY WORDS: methylotrophic bacterium, osmoprotectant, ectoine genes, transcriptional regulation

DOI: 10.1134/S0006297912080068

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