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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1qhg

E.C. nameDNA helicase
SpeciesBacillus stearothermophilus (Bacteria)
E.C. Number (IntEnz) 3.6.4.12
CSA Homologues of 1qhg1pjr,1uaa,2is1,2is2,2is4,2is6,3pjr,
CSA Entries With UniProtID P56255
CSA Entries With EC Number 3.6.4.12
PDBe Entry 1qhg
PDBSum Entry 1qhg
MACiE Entry 1qhg

Literature Report

IntroductionPcrA DNA helicase is a 3'-5' DNA helicase. It is a single-stranded DNA (ssDNA)-dependent ATPase that uses the free energy of ATP hydrolysis to unwind duplex DNA. PcrA is known to be essential in some species, such as Bacillus subtilis and Staphylococcus aureus, with roles in DNA repair and rolling circle replication.
This annotation covers the ATPase activity of PcrA.
MechansimPcrA uses Glu 224 as a general base to deprotonate the water molecule that attacks the gamma phosphate of ATP. In addition, Lys 37, Arg 387, Arg 610 and an Mg2+ ion contact the triphosphate chain of ATP and stabilise negative charge in the transition state.
Reaction

Catalytic Sites for 1qhg

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
GluA224224macie:sideChainDeprotonates the water molecule that attacks the gamma phosphate of ATP.
LysA3737macie:sideChainInteracts with the beta phosphate of ATP; stabilises negative charge in the transition state.
ArgA610610macie:sideChainPolarises the gamma phosphate of ATP, stabilising negative charge in the transition state.

Literature References

Notes:
Soultanas P
DNA binding mediates conformational changes and metal ion coordination in the active site of PcrA helicase.
J Mol Biol 1999 290 137-148
PubMed: 10388562
Velankar SS
Crystal structures of complexes of PcrA DNA helicase with a DNA substrate indicate an inchworm mechanism.
Cell 1999 97 75-84
PubMed: 10199404
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