Biochemical Properties of Single-Stranded DNA-Binding Protein from Mycobacterium smegmatis, a Fast-growing Mycobacterium and Its Physical and Functional Interaction with Uracil DNA Glycosylases

Acharya, Narottam and Varshney, Umesh (2002) Biochemical Properties of Single-Stranded DNA-Binding Protein from Mycobacterium smegmatis, a Fast-growing Mycobacterium and Its Physical and Functional Interaction with Uracil DNA Glycosylases. In: Journal of Molecular Biology, 318 (5). pp. 1251-1264.

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Abstract

The single-stranded DNA-binding proteins (SSBs) are vital to virtually all DNA functions. Here, we report on the biochemical properties of SSB from a fast-growing mycobacteria, Mycobacterium smegmatis, and the interaction of the homotetrameric SSBs with uracil DNA glycosylases (UDGs) from M. smegmatis (Msm), Mycobacterium tuberculosis (Mtu) and Escherichia coli (Eco). UDG is a crucial DNA repair enzyme, which removes the promutagenic uracil residues. MsmSSB stimulates activity of the homologous MsmUDG and of the heterologous Mtu-, and Eco-UDGs. On the contrary, while the MtuSSB stimulates the MtuUDG, it inhibits the other two UDGs. Although the MsmSSB shares 84% identity with MtuSSB, the two are strikingly different, in that MsmSSB contains a glycine-rich segment (11 out of 13 residues) in the spacer connecting the N-terminal DNA-binding domain with the C-terminal acidic tail. While the DNA-binding properties of MsmSSB, such as its affinity to oligomeric DNA, requirement of minimum size DNA and the modes of interaction are indistinguishable from those of Eco-, and Mtu-SSBs, it is unclear if the glycine-rich segment confers structural advantage to MsmSSB, responsible for its stimulatory effect on all UDGs tested. More importantly, by using a small polypeptide inhibitor of UDGs, and the deletion mutants of SSBs, we suggest that the C-terminal acidic tail of the SSBs interacts within the DNA-binding groove of the UDGs, and propose a role for SSBs in the recruitment of UDGs to the damaged DNA.

Item Type:	Journal Article
Publication:	Journal of Molecular Biology
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Ung;Ugi;SSB;UDG;Mycobacterium tuberculosis
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	05 Oct 2007
Last Modified:	24 Feb 2012 05:01
URI:	http://eprints.iisc.ac.in/id/eprint/12100

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