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Structure of Mycobacterium tuberculosis Singlestranded DNA-binding Protein. Variability in Quaternary Structure and Its Implications

Saikrishnan, K and Jeyakanthan, J and Venkatesh, J and Acharya, N and Sekar, K and Varshney, U and Vijayan, M (2003) Structure of Mycobacterium tuberculosis Singlestranded DNA-binding Protein. Variability in Quaternary Structure and Its Implications. In: Journal of Molecular Biology, 331 (2). pp. 385-393.

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Abstract

Single-stranded DNA-binding protein (SSB) is an essential protein necessary for the functioning of the DNA replication, repair and recombination machineries. Here we report the structure of the DNA-binding domain of Mycobacterium tuberculosis SSB (MtuSSB) in four different crystals distributed in two forms. The structure of one of the forms was solved by a combination of isomorphous replacement and anomalous scattering. This structure was used to determine the structure of the other form by molecular replacement. The polypeptide chain in the structure exhibits the oligonucleotide binding fold. The globular core of the molecule in different subunits in the two forms and those in Escherichia coli SSB (EcoSSB) and human mitochondrial SSB (HMtSSB) have similar structure, although the three loops exhibit considerable structural variation. However, the tetrameric MtuSSB has an as yet unobserved quaternary association. This quaternary structure with a unique dimeric interface lends the oligomeric protein greater stability, which may be of significance to the functioning of the protein under conditions of stress. Also, as a result of the variation in the quaternary structure the path adopted by the DNA to wrap around MtuSSB is expected to be different from that of EcoSSB.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: single stranded dna binding protein;homo tetrameric SSB;protein dna interactions;oligonucleotide binding fold;mycobacterium tuberculosis
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Information Sciences > BioInformatics Centre
Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 25 Oct 2004
Last Modified: 23 Feb 2012 09:23
URI: http://eprints.iisc.ernet.in/id/eprint/2113

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