title: Overexpression of the Rv0805 phosphodiesterase elicits a cAMP-independent transcriptional response.
abstract: The Rv0805 gene in Mycobacterium tuberculosis encodes a metallophosphoesterase which shows cAMP-hydrolytic activity. Overexpression of Rv0805 has been used as a tool to lower intracellular cAMP levels and thereby elucidate the roles of cAMP in mycobacteria. Here we show that levels of cAMP in M. tuberculosis were lowered by only ∼30% following overexpression of Rv0805, and transcript levels of a number of genes, which include those associated with virulence and the methyl citrate cycle, were altered. The genes that showed altered expression were distinct from those differentially regulated in a strain deleted for the cAMP-receptor protein (CRP(Mt)), consistent with the relatively low dependence on cAMP of CRP(Mt) binding to DNA. Using mutants of Rv0805 we show that the transcriptional signature of Rv0805 overexpression is a combination of catalysis-dependent and independent effects, and that the structurally flexible C-terminus of Rv0805 is crucial for the catalysis-independent effects of the protein. Our study demonstrates the dissociation of Rv0805 and cAMP-regulated gene expression, and reveals alternate functions for this phosphodiesterase from M. tuberculosis.
authors.affiliation: Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Nishad
authors.initials: N
authors.lastname: Matange
authors.forename: Debbie M
authors.initials: DM
authors.lastname: Hunt
authors.forename: Roger S
authors.initials: RS
authors.lastname: Buxton
authors.forename: Sandhya S
authors.initials: SS
authors.lastname: Visweswariah
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D002384:Catalysis; D000242:Cyclic AMP / Q000096:biosynthesis* / Q000502:physiology; D002373:Cyclic AMP Receptor Protein / Q000172:deficiency / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D011401:Promoter Regions, Genetic / Q000235:genetics; D014158:Transcription, Genetic; D059467:Transcriptome
chemical_list: D001426:Bacterial Proteins; D002373:Cyclic AMP Receptor Protein; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases
keywords: Cyclic AMP; Microarray; Mycobacterium tuberculosis; Phosphodiesterase; Rv0805