title: Mycobacterium tuberculosis groE promoter controls the expression of the bicistronic groESL1 operon and shows differential regulation under stress conditions.
abstract: Heat shock promoters of mycobacteria are strong promoters that become rapidly upregulated during macrophage infection and thus serve as valuable candidates for expressing foreign antigens in recombinant BCG vaccine. In the present study, a new heat shock promoter controlling the expression of the groESL1 operon was identified and characterized. Mycobacterium tuberculosis groESL1 operon codes for the immunodominant 10 kDa (Rv3418c, GroES/Cpn10/Hsp10) and 60 kDa (Rv3417c, GroEL1/Cpn60.1/Hsp60) heat shock proteins. The basal promoter region was 115 bp, while enhanced activity was seen only with a 277-bp fragment. No promoter element was seen in the groES-groEL1 intergenic region. This operon codes for a bicistronic mRNA transcript as determined by reverse transcriptase-PCR and Northern blot analysis. Primer extension analysis identified two transcriptional start sites (TSSs) TSS1 (-236) and TSS2 (-171), out of which one (TSS2) was heat inducible. The groE promoter was more active than the groEL2 promoter in Mycobacterium smegmatis. Further, it was found to be differentially regulated under stress conditions, while the groEL2 promoter was constitutive.
authors.affiliation: Department of Immunology, Tuberculosis Research Centre (ICMR), Chennai, India.
authors.forename: Vivekanandan
authors.initials: V
authors.lastname: Aravindhan
authors.forename: Aparna J
authors.initials: AJ
authors.lastname: Christy
authors.forename: Sougata
authors.initials: S
authors.lastname: Roy
authors.forename: Parthasarathy
authors.initials: P
authors.lastname: Ajitkumar
authors.forename: Paranji R
authors.initials: PR
authors.lastname: Narayanan
authors.forename: Sujatha
authors.initials: S
authors.lastname: Narayanan
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis*; D001483:Base Sequence; D015152:Blotting, Northern; D018833:Chaperonins / Q000096:biosynthesis*; D004269:DNA, Bacterial / Q000235:genetics*; D021901:DNA, Intergenic; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000502:physiology*; D009876:Operon; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D024363:Transcription Initiation Site; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D021901:DNA, Intergenic; C097970:GroESL protein, Bacteria; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001616:beta-Galactosidase; D018833:Chaperonins