5c10

</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5c10 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5c10 OCA], [https://pdbe.org/5c10 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5c10 RCSB], [https://www.ebi.ac.uk/pdbsum/5c10 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5c10 ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

Many dsDNA viruses encode DNA-packaging terminases, each containing a nuclease domain that resolves concatemeric DNA into genome-length units. Terminase nucleases resemble the RNase H-superfamily nucleotidyltransferases in folds, and share a two-metal-ion catalytic mechanism. Here we show that residue K428 of a bacteriophage terminase gp2 nuclease domain mediates binding of the metal cofactor Mg2+. A K428A mutation allows visualization, at high resolution, of a metal ion binding mode with a coupled-octahedral configuration at the active site, exhibiting an unusually short metal-metal distance of 2.42 A. Such proximity of the two metal ions may play an essential role in catalysis by generating a highly positive electrostatic niche to enable formation of the negatively charged pentacovalent phosphate transition state, and provides the structural basis for distinguishing Mg2+ from Ca2+. Using a metal ion chelator beta-thujaplicinol as a molecular probe, we observed a second mode of metal ion binding at the active site, mimicking the DNA binding state. Arrangement of the active site residues differs drastically from those in RNase H-like nucleases, suggesting a drifting of the active site configuration during evolution. The two distinct metal ion binding modes unveiled mechanistic details of the two-metal-ion catalysis at atomic resolution.

Two distinct modes of metal ion binding in the nuclease active site of a viral DNA-packaging terminase: insight into the two-metal-ion catalytic mechanism.,Zhao H, Lin Z, Lynn AY, Varnado B, Beutler JA, Murelli RP, Le Grice SF, Tang L Nucleic Acids Res. 2015 Oct 7. pii: gkv1018. PMID:26450964<ref>PMID:26450964</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

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