1mc8
From Proteopedia
Crystal Structure of Flap Endonuclease-1 R42E mutant from Pyrococcus horikoshii
Structural highlights
Function[FEN_PYRHO] Structure-specific nuclease with 5'-flap endonuclease and 5'-3' exonuclease activities involved in DNA replication and repair. During DNA replication, cleaves the 5'-overhanging flap structure that is generated by displacement synthesis when DNA polymerase encounters the 5'-end of a downstream Okazaki fragment. Binds the unpaired 3'-DNA end and kinks the DNA to facilitate 5' cleavage specificity. Cleaves one nucleotide into the double-stranded DNA from the junction in flap DNA, leaving a nick for ligation. Also involved in the base excision repair (BER) pathway. Acts as a genome stabilization factor that prevents flaps from equilibrating into structures that lead to duplications and deletions. Also possesses 5'-3' exonuclease activity on nicked or gapped double-stranded DNA (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe crystal structure of flap endonuclease-1 from Pyrococcus horikoshii (phFEN-1) was determined to a resolution of 3.1 A. The active cleft of the phFEN-1 molecule is formed with one large loop and four small loops. We examined the function of the conserved residues and positively charged clusters on these loops by kinetic analysis with 45 different mutants. Arg(40) and Arg(42) on small loop 1, a cluster Lys(193)-Lys(195) on small loop 2, and two sites, Arg(94) and Arg(118)-Lys(119), on the large loop were identified as binding sites. Lys(87) on the large loop may play significant roles in catalytic reaction. Furthermore, we successfully elucidated the function of the four DNA binding sites that form productive ES complexes specific for each endo- or exo-type hydrolysis, probably by bending the substrates. For the endo-activity, Arg(94) and Lys(193)-Lys(195) located at the top and bottom of the molecule were key determinants. For the exo-activity, all four sites were needed, but Arg(118)-Lys(119) was dominant. The major binding sites for both the nick substrate and double-stranded DNA might be the same. Molecular structure and novel DNA binding sites located in loops of flap endonuclease-1 from Pyrococcus horikoshii.,Matsui E, Musti KV, Abe J, Yamasaki K, Matsui I, Harata K J Biol Chem. 2002 Oct 4;277(40):37840-7. Epub 2002 Jul 29. PMID:12147694[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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