Uracil excision repair in Mycobacterium tuberculosis cell-free extracts

Kumar, Pradeep and Bharti, Sanjay Kumar and Varshney, Umesh (2011) Uracil excision repair in Mycobacterium tuberculosis cell-free extracts. In: Tuberculosis, 91 (3). pp. 212-218.

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Abstract

Uracil excision repair is ubiquitous in all domains of life and initiated by uracil DNA glycosylases (UDGs) which excise the promutagenic base, uracil, from DNA to leave behind an abasic site (AP-site). Repair of the resulting AP-sites requires an AP-endonuclease, a DNA polymerase, and a DNA ligase whose combined activities result in either short-patch or long-patch repair. Mycobacterium tuberculosis, the causative agent of tuberculosis, has an increased risk of accumulating uracils because of its G + C-rich genome, and its niche inside host macrophages where it is exposed to reactive nitrogen and oxygen species, two major causes of cytosine deamination (to uracil) in DNA. In vitro assays to study DNA repair in this important human pathogen are limited. To study uracil excision repair in mycobacteria, we have established assay conditions using cell-free extracts of M. tuberculosis and M. smegmatis (a fast-growing mycobacterium) and oligomer or plasmid DNA substrates. We show that in mycobacteria, uracil excision repair is completed primarily via long-patch repair. In addition, we show that M. tuberculosis UdgB, a newly characterized family 5 UDG, substitutes for the highly conserved family 1 UDG, Ung, thereby suggesting that UdgB might function as backup enzyme for uracil excision repair in mycobacteria. (C) 2011 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	Tuberculosis
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Ung;UdgB;Short-patch repair;Long-patch repair
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	15 Jun 2011 06:51
Last Modified:	15 Jun 2011 06:51
URI:	http://eprints.iisc.ac.in/id/eprint/38037

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