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Characterization of phylogenetically distant members of the adenylate cyclase family from mycobacteria: Rv1647 from Mycobacterium tuberculosis and its orthologue ML1399 from M. leprae

Shenoy, Avinash R and Sreenath, Nandini P and Mahalingam, Mohan and Visweswariah, Sandhya S (2005) Characterization of phylogenetically distant members of the adenylate cyclase family from mycobacteria: Rv1647 from Mycobacterium tuberculosis and its orthologue ML1399 from M. leprae. In: Biochemical Journal, 387 . pp. 541-551.

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Abstract

Analysis of the genome sequence of Mycobacterium tuberculosis H37Rv has identified 16 genes that are similar to the mammalian adenylate andguanylate cyclases. Rv1647 was predicted to be an active adenylate cyclase but its position in a phylogenetically distant branch from the other enzymes characterized so far from M. tuberculosis makes it an interestingly divergent nucleotide cyclase to study. In agreement with its divergence at the sequence level from other nucleotide cyclases,the cloning, expression and purification of Rv1647 revealed differences in its biochemical properties from the previously characterized Rv1625 cadenylate cyclase. Adenylate cyclase activity of Rv1647 was activated by detergents but was resistant to high concentrations of salt.Mutations of substrate-specifying residues to those present inguanylate cyclases failed to convert the enzyme into a guanylate cyclase, and did not alter its oligomeric status. Orthologues of Rv1647 could be found in M. leprae, M. avium and M. smegmatis. The orthologue from M. leprae (ML 1399) was cloned, and the protein was expressed,purified and shown biochemically to be an adenylate cyclase, thus representing the first adenylate cyclase to be described from M.leprae. Importantly, Western-blot analysis of subcellular fractions from M. tuberculosis and M. leprae revealed that the Rv1647 and ML 1399gene products respectively were expressed in these bacteria.Additionally, M. tuberculosis was also found to express the Rv1625 cadenylate cyclase, suggesting that multiple adenylate cyclase proteinsmay be expressed simultaneously in this organism. These results suggest that class III cyclase-like gene products probably have an important role to play in the physiology and perhaps the pathology of these medically important bacteria.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Portland Press.
Keywords: adenylate cyclase;cAMP;enzyme;Mycobacterium leprae;Mycobacterium tuberculosis;phylogenetic analysis
Department/Centre: Division of Biological Sciences > Molecular Reproduction, Development & Genetics (formed by the merger of DBGL and CRBME)
Date Deposited: 19 May 2005
Last Modified: 19 Sep 2010 04:18
URI: http://eprints.iisc.ernet.in/id/eprint/3229

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