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The multiple stress responsive transcriptional regulator Rv3334 of Mycobacterium tuberculosis is an autorepressor and a positive regulator of kstR
Author(s) -
Gomez Roshna Lawrence,
Jose Leny,
Ramachandran Ranjit,
Raghunandanan Sajith,
Muralikrishnan Balaji,
Johnson John Bernet,
Sivakumar Krishnankutty Chandrika,
Mundayoor Sathish,
Kumar Ramakrishnan Ajay
Publication year - 2016
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.13791
Subject(s) - regulator , transcriptional regulation , biology , reporter gene , microbiology and biotechnology , repressor , enhancer , promoter , gene , downregulation and upregulation , gene expression , genetics
Rv3334 protein of Mycobacterium tuberculosis belongs to the MerR family of transcriptional regulators and is upregulated during hypoxia and other stress conditions. Employing GFP reporter constructs, mobility shift assays and Ch IP assays, we demonstrate that Rv3334 binds to its own promoter and acts as an autorepressor. We were able to locate a 22 bp palindrome in its promoter that we show to be the cognate binding sequence of Rv3334. Using chase experiments, we could conclusively prove the requirement of this palindrome for Rv3334 binding. Recombinant Rv3334 readily formed homodimers in vitro , which could be necessary for its transcriptional regulatory role in vivo . Although the DNA ‐binding activity of the protein was abrogated by the presence of certain divalent metal cations, the homodimer formation remained unaffected. In silico predictions and subsequent assays using GFP reporter constructs and mobility shift assays revealed that the expression of ketosteroid regulator gene ( kstR ), involved in lipid catabolism, is positively regulated by Rv3334. Ch IP assays with aerobically grown M. tuberculosis as well as dormant bacteria unambiguously prove that Rv3334 specifically upregulates expression of kstR during dormancy. Our study throws light on the possible role of Rv3334 as a master regulator of lipid catabolism during hypoxia‐induced dormancy.

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