Glutamate racemase from Mycobacterium tuberculosis inhibits DNA gyrase by affecting its DNA-binding

Sengupta, Sugopa and Shah, Meera and Nagaraja, Valakunja (2006) Glutamate racemase from Mycobacterium tuberculosis inhibits DNA gyrase by affecting its DNA-binding. In: Nucleic Acids Research, 34 (19). pp. 5567-5576.

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Abstract

Glutamate racemase (MurI) catalyses the conversion of L-glutamate to D-glutamate, an important component of the bacterial cell wall. MurI from Escherichia coli inhibits DNA gyrase in presence of the peptidoglycan precursor. Amongst the two-glutamate racemases found in Bacillus subtilis, only one inhibits gyrase, in absence of the precursor. Mycobacterium tuberculosis has a single gene encoding glutamate racemase. Action of M.tuberculosis MurI on DNA gyrase activity has been examined and its mode of action elucidated. We demonstrate that mycobacterial MurI inhibits DNA gyrase activity, in addition to its precursor independent racemization function. The inhibition is not species-specific as E.coli gyrase is also inhibited but is enzyme-specific as topoisomerase I activity remains unaltered. The mechanism of inhibition is different from other well-known gyrase inhibitors. MurI binds to GyrA subunit of the enzyme leading to a decrease in DNA-binding of the holoenzyme. The sequestration of the gyrase by MurI results in inhibition of all reactions catalysed by DNA gyrase. MurI is thus not a typical potent inhibitor of DNA gyrase and instead its role could be in modulation of the gyrase activity.

Item Type:	Journal Article
Publication:	Nucleic Acids Research
Publisher:	Oxford University Press
Additional Information:	Copyright of this article belongs to Oxford University Press.
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	20 Dec 2006
Last Modified:	19 Sep 2010 04:33
URI:	http://eprints.iisc.ac.in/id/eprint/9152

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