1xwl
From Proteopedia
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BACILLUS STEAROTHERMOPHILUS (NEWLY IDENTIFIED STRAIN AS YET UNNAMED) DNA POLYMERASE FRAGMENT
Overview
BACKGROUND: The study of DNA polymerases in the Pol l family is central to, the understanding of DNA replication and repair. DNA polymerases are used, in many molecular biology techniques, including PCR, which require a, thermostable polymerase. In order to learn about Pol I function and the, basis of thermostability, we undertook structural studies of a new, thermostable DNA polymerase. RESULTS: A DNA polymerase large, Klenow-like, fragment from a recently identified thermostable strain of Bacillus, stearothermophilus (BF) was cloned, sequenced, overexpressed and, characterized. Its crystal structure was determined to 2.1 A resolution by, the method of multiple isomorphous replacement. CONCLUSIONS: This, structure represents the highest resolution view of a Pol I enzyme, obtained to date. Comparison of the three Pol I structures reveals no, compelling evidence for many of the specific interactions that have been, proposed to induce thermostability, but suggests that thermostability, arises from innumerable small changes distributed throughout the protein, structure. The polymerase domain is highly conserved in all three, proteins. The N-terminal domains are highly divergent in sequence, but, retain a common fold. When present, the 3'-5' proofreading exonuclease, activity is associated with this domain. Its absence is associated with, changes in catalytic residues that coordinate the divalent ions required, for activity and in loops connecting homologous secondary structural, elements. In BF, these changes result in a blockage of the DNA-binding, cleft.
About this Structure
1XWL is a Single protein structure of sequence from Geobacillus stearothermophilus with SO4 as ligand. This structure superseeds the now removed PDB entry 1BDP. Active as DNA-directed DNA polymerase, with EC number 2.7.7.7 Full crystallographic information is available from OCA.
Reference
Crystal structure of a thermostable Bacillus DNA polymerase I large fragment at 2.1 A resolution., Kiefer JR, Mao C, Hansen CJ, Basehore SL, Hogrefe HH, Braman JC, Beese LS, Structure. 1997 Jan 15;5(1):95-108. PMID:9016716
Page seeded by OCA on Wed Nov 21 06:23:38 2007
