Molecular characterization of FinR, a novel redox-sensing transcriptional regulator in Pseudomonas putida KT2440

Sujin Yeom, Jinki Yeom, Woojun Park

Research output: Contribution to journalArticle

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Abstract

FinR is required for the induction of fpr (ferredoxin-NADP + reductase) under superoxide stress conditions in Pseudomonas putida. Many proteobacteria harbour FinR homologues in their genome as a putative LysR-type protein. Three cysteine residues (at positions 150, 239 and 289 in P. putida FinR) are conserved in all FinR homologues. When these conserved cysteines, along with two other cysteine residues present in FinR, were individually mutated to serines, the FinR remained active, unlike SoxR and OxyR in Escherichia coli. The results of our in vitro DNA-binding assay with cellular extracts showed that FinR binds directly to the fpr promoter region. In order to identify the FinR functional domain for sensing superoxide stress, we employed random and site-directed mutagenesis of FinR. Among 18 single amino acid mutants, three mutants (T39A, R194A and E225A) abolished fpr induction without any alteration of their DNA-binding ability, whereas other mutants also abrogated their DNA-binding abilities. Interestingly, two mutants (L215P and D51A) appeared to be constitutively active, regardless of superoxide stress conditions. Ferrous iron depletion, ferric iron addition and fdxA (ferredoxin) gene deletion also participate in the regulation of fpr. These data indicate that FinR has unusual residues for redox sensing and that the redox-sensing mechanism of FinR differs from the well-known mechanisms of OxyR and SoxR.

Original languageEnglish
Pages (from-to)1487-1496
Number of pages10
JournalMicrobiology
Volume156
Issue number5
DOIs
Publication statusPublished - 2010 May 1

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Ferredoxin-NADP Reductase
Pseudomonas putida
Oxidation-Reduction
Superoxides
Cysteine
DNA
Iron
Proteobacteria
Ferredoxins
Gene Deletion
Site-Directed Mutagenesis
Genetic Promoter Regions
Serine
Genome
Escherichia coli
Amino Acids
Proteins

ASJC Scopus subject areas

  • Microbiology

Cite this

Molecular characterization of FinR, a novel redox-sensing transcriptional regulator in Pseudomonas putida KT2440. / Yeom, Sujin; Yeom, Jinki; Park, Woojun.

In: Microbiology, Vol. 156, No. 5, 01.05.2010, p. 1487-1496.

Research output: Contribution to journalArticle

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