2nq9
High resolution crystal structure of Escherichia coli endonuclease IV (Endo IV) Y72A mutant bound to damaged DNA
OverviewOverview
Escherichia coli endonuclease IV is an archetype for an abasic or apurinic-apyrimidinic endonuclease superfamily crucial for DNA base excision repair. Here biochemical, mutational and crystallographic characterizations reveal a three-metal ion mechanism for damage binding and incision. The 1.10-A resolution DNA-free and the 2.45-A resolution DNA-substrate complex structures capture substrate stabilization by Arg37 and reveal a distorted Zn(3)-ligand arrangement that reverts, after catalysis, to an ideal geometry suitable to hold rather than release cleaved DNA product. The 1.45-A resolution DNA-product complex structure shows how Tyr72 caps the active site, tunes its dielectric environment and promotes catalysis by Glu261-activated hydroxide, bound to two Zn(2+) ions throughout catalysis. These structural, mutagenesis and biochemical results suggest general requirements for abasic site removal in contrast to features specific to the distinct endonuclease IV alpha-beta triose phosphate isomerase (TIM) barrel and APE1 four-layer alpha-beta folds of the apurinic-apyrimidinic endonuclease families.
About this StructureAbout this Structure
2NQ9 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
DNA apurinic-apyrimidinic site binding and excision by endonuclease IV., Garcin ED, Hosfield DJ, Desai SA, Haas BJ, Bjoras M, Cunningham RP, Tainer JA, Nat Struct Mol Biol. 2008 Apr 13;. PMID:18408731 Page seeded by OCA on Thu Apr 24 09:25:13 2008