Mycobacterium tuberculosis UvrB Is a Robust DNA-Stimulated ATPase That Also Possesses Structure-Specific ATP-Dependent DNA Helicase Activity

Thakur, Manoj and Kumar, Mohan BJ and Muniyappa, K (2016) Mycobacterium tuberculosis UvrB Is a Robust DNA-Stimulated ATPase That Also Possesses Structure-Specific ATP-Dependent DNA Helicase Activity. In: BIOCHEMISTRY, 55 (41). pp. 5865-5883.

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Abstract

Much is known about the Escherichia colt nucleotide excision repair (NER) pathway; however, very little is understood about the proteins involved and the molecular mechanism of NER in mycobaCteria. In this study, we show that Mycobacterium tuberculosis UvrB (MtUvrB), which exists in solution as a monomer, binds to DNA in a structure-dependent manner. A systematic examination of MtUvrB substrate specificity reveals that it associates preferentially with single-stranded DNA, duplexes with 3' or 5' overhangs, and linear duplex DNA with splayed arms. Whereas E. coli UvrB (EcUvrB) binds weakly to undamaged DNA and has no ATPase activity, MtUvrB possesses intrinsic ATPase activity that is greatly stimulated by both single and double-stranded DNA. Strikingly, we found that MtUvrB, but not EcUvrB, possesses the DNA unwinding activity characteristic of an ATP-dependent DNA helicase. The helicase activity of MtUvrB proceeds in the 3' to S' direction and is strongly modulated by a nontranslocating 5' single-stranded tail, indicating that in addition to the translocating strand it also, interacts with. the 5' end of the substrate. The fraction of DNA unwound by MtUvrB decreases significantly as the length, of theiduplex increases: it fails to unwind duplexes longer than 70 bp. These results, on one hand, reveal significant mechanistic differences between MtUvrB and EcUvrB and, on the other, support an alternative role for UvrB in the processing of key DNA replication intermediates. Altogether, our findings. provide insights into the catalytic functions of UvrB and lay the foundation for further understanding of the NER pathway in k tuberculosis.

Item Type:	Journal Article
Publication:	BIOCHEMISTRY
Additional Information:	Copy right dir this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	03 Dec 2016 10:13
Last Modified:	03 Dec 2016 10:13
URI:	http://eprints.iisc.ac.in/id/eprint/55414

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