Study of the ATP-binding site of helicase IV from Escherichia coli.
Helicases contain conserved motifs involved in ATP/magnesium/nucleic acid binding and in the mechanisms coupling nucleotide hydrolysis to duplex unwinding. None of these motifs are located at the adenine-binding pocket of the protein. We show here that the superfamily I helicase, helicase IV from Escherichia coli, utilizes a conserved glutamine and conserved aromatic residue to interact with ATP. Other superfamily I helicases such as, UvrD/Rep/PcrA also possess these residues but in addition they interact with adenine via a conserved arginine, which is replaced by a serine in helicase IV. Mutation of this serine residue in helicase IV into histidine or methionine leads to proteins with unaffected ATPase and DNA-binding activities but with low helicase activity. This suggests that residues located at the adenine-binding pocket, in addition to be involved in ATP-binding, are important for efficient coupling between ATP hydrolysis and DNA unwinding.
Dubaele
Sandy
S
Novartis Institutes for Biomedical Research, Oncology Department, CH-4002 Basel, Switzerland.
Lourdel
Claude
C
Chène
Patrick
P
D000225:Adenine / Q000737:chemistry / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D017124:Conserved Sequence; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C059716:helD protein, E coli; D004265:DNA Helicases; D000225:Adenine