Defining the roles of individual residues in the single-stranded DNA binding site of PcrA helicase
AUTOR(ES)
Dillingham, Mark S.
FONTE
The National Academy of Sciences
RESUMO
Crystal structures and biochemical analyses of PcrA helicase provide evidence for a model for processive DNA unwinding that involves coupling of single-stranded DNA (ssDNA) tracking to a duplex destabilization activity. The DNA tracking model invokes ATP-dependent flipping of bases between several pockets on the enzyme formed by conserved aromatic amino acid residues. We have used site-directed mutagenesis to confirm the requirement of all of these residues for helicase activity. We also demonstrate that the duplex unwinding defects correlate with an inability of certain mutant proteins to translocate effectively on ssDNA. Moreover, the results define an essential triad of residues within the ssDNA binding site that comprise the ATP-driven DNA motor itself.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=37447Documentos Relacionados
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