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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1nsf

E.C. namevesicle-fusing ATPase
SpeciesCricetulus griseus (Chinese hamster)
E.C. Number (IntEnz) 3.6.4.6
CSA Homologues of 1nsfThere are 27 Homologs
CSA Entries With UniProtID P18708
CSA Entries With EC Number 3.6.4.6
PDBe Entry 1nsf
PDBSum Entry 1nsf
MACiE Entry 1nsf

Literature Report

IntroductionN-ethylmaleimide sensitive factor is responsible for the destabilisation and disassembly of the proteins in the SNARE complex thus has a key role in vesicular trafficking inside the cell. The structure described in this pdb code is of the ATP binding domain which contains the active site necessary for ATP hydrolysis: conformational changes that occur as a result of the hydrolysis lead to the breaking up of the SNARE complex. The ATP binding domain of the protein shares homology with other Rossmann fold containing proteins, particularly with E.coli DNA polymerase III.
MechansimHydrolysis of ATP is facilitated by a Mg2+ ion and two Lysine residues (Lys 549 and Lys 708) which contact the beta and gamma phosphates of the ATP. This enables the conformational changes that cause the breaking up of the hexameric protein and the collapse of the SNARE complex. However, in order to reduce the rate that this occurs to allow the protein to interact with the SNARE complex before breaking up, Lys 631 acts to reduce the rate of hydrolysis so that ATP stays bound for as long as possible.
Reaction

Catalytic Sites for 1nsf

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysA708708macie:sideChainForms electrostatic contact with the gamma phosphate of ATP thus stabilises the pentavalent phosphate that forms when hydrolysis occurs.
LysA631631macie:sideChainActs to reduce the rate at which incoming water molecules are deprotonated, thus reducing the rate of nucleophilic attack on the ATP. This has the overall effect of speeding up the dissociation of the SNARE complex because it allows the hexamer to remain intact whilst binding to the SNARE complex.
LysA549549macie:sideChainForms electrostatic contacts to the gamma phosphate of ATP, thus stabilising the pentavalent phosphate intermediate thus facilitating hydrolysis of ATP.

Literature References

Notes:
Yu RC
Structure of the ATP-dependent oligomerization domain of N-ethylmaleimide sensitive factor complexed with ATP.
Nat Struct Biol 1998 5 803-811
PubMed: 9731775
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