Publication Abstract from PubMed
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 Zn3-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 Zn2+ 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.
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 May;15(5):515-22. Epub 2008 Apr 13. PMID:18408731[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
