Open AccessMycobacterium tuberculosis groE promoter controls the expression of the bicistronic groESL1 operon and shows differential regulation under stress conditions
Author(s) -
Aravindhan Vivekanandan,
Christy Aparna J.,
Roy Sougata,
Ajitkumar Parthasarathy,
Narayanan Paranji R.,
Narayanan Sujatha
Publication year - 2009
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2008.01465.x
Subject(s) - operon , promoter , biology , mycobacterium smegmatis , heat shock protein , microbiology and biotechnology , plasmid , mycobacterium tuberculosis , l arabinose operon , gene , gene expression , genetics , tuberculosis , escherichia coli , medicine , pathology
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.