TY  - JOUR
N1  - OPEN ACCESS
ID  - open992
UR  - http://nar.oxfordjournals.org/content/33/8/2707.full.pdf+html
A1  - Jain, R K
A1  - Kapur, Manisha
A1  - Labana, S
A1  - Sarma, P.M.
A1  - Lal, Banwari
A1  - Bhattacharya, D.
A1  - Thakur, I.S.
Y1  - 2005///
N2  - 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.
PB  - IISc
JF  - Current Science
VL  - 89
TI  - Microbial Diversity: Application on micro-organisms for the biodegradation of xenobiotics
SP  - 101
AV  - public
EP  - 112
ER  -