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- Title
Site-directed mutagenesis of motif III in PcrA helicase reveals a role in coupling ATP hydrolysis to strand separation.
- Authors
Dillingham, M S; Soultanas, P; Wigley, D B
- Abstract
Motif III is one of the seven protein motifs that are characteristic of superfamily I helicases. To investigate its role in the helicase mechanism we have introduced a variety of mutations at three of the most conserved amino acid residues (Q254, W259 and R260). Biochemical characterisation of the resulting proteins shows that mutation of motif III affects both ATP hydrolysis and single-stranded DNA binding. We propose that amino acid residue Q254 acts as a gamma-phosphate sensor at the nucleotide binding pocket transmitting conformational changes to the DNA binding site, since the nature of the charge on this residue appears to control the degree of coupling between ATPase and helicase activities. Residues W259 and R260 both participate in direct DNA binding interactions that are critical for helicase activity.
- Publication
Nucleic acids research, 1999, Vol 27, Issue 16, p3310
- ISSN
1362-4962
- Publication type
Journal Article
- DOI
10.1093/nar/27.16.3310