3pjr
From Proteopedia
HELICASE SUBSTRATE COMPLEX
Structural highlights
FunctionPCRA_GEOSE DNA helicase. Has a broad nucleotide specificity, even being able to hydrolyze ethenonucleotides, and is able to couple the hydrolysis to unwinding of DNA substrates. It is a 3'-5' helicase but at high protein concentrations it can also displace a substrate with a 5' tail. Preferred substrate being one with both single and double-stranded regions of DNA. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedWe have determined two different structures of PcrA DNA helicase complexed with the same single strand tailed DNA duplex, providing snapshots of different steps on the catalytic pathway. One of the structures is of a complex with a nonhydrolyzable analog of ATP and is thus a "substrate" complex. The other structure contains a bound sulphate ion that sits in a position equivalent to that occupied by the phosphate ion produced after ATP hydrolysis, thereby mimicking a "product" complex. In both complexes, the protein is monomeric. Large and distinct conformational changes occur on binding DNA and the nucleotide cofactor. Taken together, these structures provide evidence against an "active rolling" model for helicase action but are instead consistent with an "inchworm" mechanism. Crystal structures of complexes of PcrA DNA helicase with a DNA substrate indicate an inchworm mechanism.,Velankar SS, Soultanas P, Dillingham MS, Subramanya HS, Wigley DB Cell. 1999 Apr 2;97(1):75-84. PMID:10199404[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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