Comparative genomic analysis of mycobacteria (actinobacteria): redundancy in function among serine threonine protein kinases.

Harini, L.; Narayanan, S.

Global Journal of Bio-Science and Biotechnology; 2013; 2; 393-398.

Abstract: Mycobacterium tuberculosis is one of the most adaptable pathogens ever know which continues to take a heavy toll despite the availability of a vaccine and good antimicrobial regimen. The pathogen's malleability is well reflected in its increasing mutability leading to emergence of drug resistance, existence of multiple species with host preferences, and the ability to sense, survive and modulate the defense mechanisms in the host. Detailed comparison with prototype STPKs (cPKA a ) is useful in identifying STPKs in the Mycobacterial genus which can be grouped into a family called ‘Eukaryotic like STPKs'. The homologous nature of the kinase domains among these kinases implies that all of them fold into topologically similar 3-dimensional core structures and impart phosphor transfer according to a common mechanism. There are 11 representatives each of the prokaryotic HK-RR pair and the eukaryotic like serine/threonine protein kinase system in M.tuberculosis . The occurrence of both eukaryotic-like and prokaryotic signaling modules may seem like a huge genetic burden and an unwanted expense of metabolic reserves especially when viewed in the backdrop of functional and mechanistic redundance among kinases. Furthermore, it has been recently reported that multiple serine threonine kinases are able to phosphorylate a single substrate and vice versa. The existence of functionally redundant kinases has always attracted the attention of researches in mycobacteriology as it presents an impediment in interpreting phenotypic effects of individual STPKs. We aimed to address this issue of redundancy through comparative genome analysis.

Keywords: Ecophysiology, Serine threonine protein kinases, PknL, Gene duplication, Copy number variation, Phylogenetic analysis, Actinobacteria, Stress response, Gene duplication, Adaptation

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