PMID:22464736

Citation	Stapleton, MR, Smith, LJ, Hunt, DM, Buxton, RS and Green, J (2012) Mycobacterium tuberculosis WhiB1 represses transcription of the essential chaperonin GroEL2. Tuberculosis (Edinb) 92:328-32
Abstract	A central feature of TB pathogenesis is the formation of Mycobacterium tuberculosis latent infections that can persist for decades. Nitric oxide produced by infected lung macrophages promotes expression of genes associated with dormancy, and impaired nitric oxide production can lead to reactivation of latent disease. Recently, WhiB1 was identified as a nitric oxide-responsive transcription factor. Here it is shown that apo-WhiB1 binds to groEL2 (Rv0440) promoter DNA. Apo-WhiB1 inhibited transcription from the groEL2 promoter in vitro and the transcript start was located ∼181 bases upstream of the groEL2 start codon. Electrophoretic mobility shift assays with sub-fragments of the groEL2 promoter indicated that the complete Rv0439c-Rv0440 intergenic region was required for WhiB1 binding, suggesting that this region possessed more than one WhiB1-binding site. DNase I footprinting identified a WhiB1-binding region that overlapped the -35 element of the groEL2 promoter. The CRP-family transcription factor Cmr (Rv1675c) was shown to bind the groEL2 promoter and activate transcription in vitro in the presence or absence of cAMP. Therefore, it is suggested that WhiB1 acts to oppose Cmr-mediated cAMP-independent activation of groEL2 expression in the presence of nitric oxide by promoter occlusion.
Links	PubMed PMC3430963 Online version:10.1016/j.tube.2012.03.001
Keywords	Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Bacterial Proteins/physiology; Base Sequence; Binding Sites/genetics; Chaperonin 60/genetics; Chaperonin 60/metabolism; DNA Footprinting/methods; DNA, Bacterial/genetics; DNA, Intergenic/genetics; Electrophoretic Mobility Shift Assay/methods; Gene Expression Regulation/drug effects; Genes, Bacterial; Humans; Iron-Sulfur Proteins/metabolism; Molecular Sequence Data; Mycobacterium tuberculosis/drug effects; Mycobacterium tuberculosis/genetics; Mycobacterium tuberculosis/metabolism; Nitric Oxide/pharmacology; Promoter Regions, Genetic; Transcription Factors/genetics; Transcription Factors/metabolism; Transcription Factors/physiology; Transcription, Genetic
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
MYCTU:WHIB1		GO:0045892: negative regulation of transcription, DNA-templated	ECO:0000314:		P		Figure 2. Apo-WhiB1 inhibits transcription of groEL2 in vitro	complete CACAO 6291
MYCTU:WHIB1	involved_in	GO:0045892: negative regulation of transcription, DNA-templated	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete

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