6grb | pdb_00006grb

eukaryotic junction-resolving enzyme GEN-1 binding with Potassium

spinqualitylabelsall models 6grb, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6grb is a 3 chain structure with sequence from Chatd. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MG Gene: CTHT_0007290 (CHATD) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed GEN1 is a member of the FEN/EXO family of structure-selective nucleases that cleave 1 nt 3' to a variety of branchpoints. For each, the H2TH motif binds a monovalent ion and plays an important role in binding one helical arm of the substrates. We investigate here the importance of this metal ion on substrate specificity and GEN1 structure. In the presence of K+ ions the substrate specificity is wider than in Na+, yet four-way junctions remain the preferred substrate. In a combination of K+ and Mg2+ second strand cleavage is accelerated 17-fold, ensuring bilateral cleavage of the junction. We have solved crystal structures of Chaetomium thermophilum GEN1 with Cs+, K+ and Na+ bound. With bound Cs+ the loop of the H2TH motif extends toward the active site so that D199 coordinates a Mg2+, buttressed by an interaction of the adjacent Y200. With the lighter ions bound the H2TH loop changes conformation and retracts away from the active site. We hypothesize this conformational change might play a role in second strand cleavage acceleration. A monovalent ion in the DNA binding interface of the eukaryotic junction-resolving enzyme GEN1.,Liu Y, Freeman ADJ, Declais AC, Lilley DMJ Nucleic Acids Res. 2018 Sep 24. pii: 5106143. doi: 10.1093/nar/gky863. PMID:30247722 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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