Microbial Diversity: Application on micro-organisms for the biodegradation of xenobiotics

Jain, R K and Kapur, Manisha and Labana, S and Sarma, P.M. and Lal, Banwari and Bhattacharya, D. and Thakur, I.S. (2005) Microbial Diversity: Application on micro-organisms for the biodegradation of xenobiotics. Current Science, 89. pp. 101-112.

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Official URL: http://nar.oxfordjournals.org/content/33/8/2707.fu...

Abstract

The reason for secretion of nucleoside diphosphate kinase (NdK), an enzyme involved in maintaining the cellular pool of nucleoside triphosphates in both prokaryotes and eukaryotes, by Mycobacterium tuberculosis is intriguing. We recently observed that NdK from M.tuberculosis (mNdK) localizes within nuclei of HeLa and COS-1 cells and also nicks chromosomalDNAin situ (A. K. Saini, K. Maithal, P. Chand, S. Chowdhury, R. Vohra, A. Goyal, G. P. Dubey, P. Chopra, R. Chandra, A. K. Tyagi, Y. Singh and V. Tandon (2004) J. Biol. Chem., 279, 50142–50149). In the current study, using a molecular beacon approach, we demonstrate that the mNdK catalyzes the cleavage of single strand DNA. It displays Michaelis–Menten kinetics with a kcat/KM of 9.65 (–0.88) · 106 M�1 s�1. High affinity (Kd � KM of �66 nM) and sequence-specific binding to the sense strand of the nuclease hypersensitive region in the c-myc promoter was observed. This is the first study demonstrating that the cleavage reaction is also enzyme-catalyzed in addition to the enzymatic kinase activity of multifunctional NdK. Using our approach, we demonstrate that GDP competitively inhibits the nuclease activity with a KI of �1.9 mM. Recent evidence implicates mNdK as a potent virulence factor in tuberculosis owing to its DNase-like activity. In this context, our results demonstrate a molecular mechanism that could be the basis for assessing in situ DNA damage by secretory mNdK.

Item Type: Article
Additional Information: OPEN ACCESS
Subjects: Q Science > QR Microbiology
Depositing User: Dr. K.P.S.Sengar
Date Deposited: 15 Feb 2012 14:38
Last Modified: 15 Feb 2012 14:38
URI: http://crdd.osdd.net/open/id/eprint/992

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