Structural highlights
Function[DPO3B_MYCTU] DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. The beta chain is required for initiation of replication once it is clamped onto DNA, it slides freely (bidirectional and ATP-independent) along duplex DNA (By similarity). Publication Abstract from PubMedThe sliding clamp is a key component of DNA polymerase III (Pol III) required for genome replication. It is known to function with diverse DNA repair proteins and cell cycle-control proteins, making it a potential drug target. To extend our understanding of the structure/function relationship of the sliding clamp, we solved the crystal structure of the sliding clamp from Mycobacterium tuberculosis (M. tuberculosis), a human pathogen that causes most cases of tuberculosis (TB). The sliding clamp from M. tuberculosis forms a ring-shaped head-to-tail dimer with three domains per subunit. Each domain contains two alpha helices in the inner ring that lie against two beta sheets in the outer ring. Previous studies have indicated that many Escherichia coli clamp-binding proteins have a conserved LF sequence, which is critical for binding to the hydrophobic region of the sliding clamp. Here, we analyzed the binding affinities of the M. tuberculosis sliding clamp and peptides derived from the alpha and delta subunits of Pol III, which indicated that the LF motif also plays an important role in the binding of the alpha and delta subunits to the sliding clamp of M. tuberculosis. Crystal structure of DNA polymerase III beta sliding clamp from Mycobacterium tuberculosis.,Gui WJ, Lin SQ, Chen YY, Zhang XE, Bi LJ, Jiang T Biochem Biophys Res Commun. 2011 Feb 11;405(2):272-7. Epub 2011 Jan 8. PMID:21219854[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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