3n7b

Publication Abstract from PubMed

SgrAI is a type II restriction endonuclease that cuts an unusually long recognition sequence and exhibits allosteric self-activation with expansion of DNA-sequence specificity. The three-dimensional crystal structures of SgrAI bound to cleaved primary-site DNA and Mg(2)(+) and bound to secondary-site DNA with either Mg(2)(+) or Ca(2)(+) are presented. All three structures show a conformation of enzyme and DNA similar to the previously determined dimeric structure of SgrAI bound to uncleaved primary-site DNA and Ca(2)(+) [Dunten et al. (2008), Nucleic Acids Res. 36, 5405-5416], with the exception of the cleaved bond and a slight shifting of the DNA in the SgrAI/cleaved primary-site DNA/Mg(2)(+) structure. In addition, a new metal ion binding site is located in one of the two active sites in this structure, which is consistent with proposals for the existence of a metal-ion site near the 3'-O leaving group.

New clues in the allosteric activation of DNA cleavage by SgrAI: structures of SgrAI bound to cleaved primary-site DNA and uncleaved secondary-site DNA.,Little EJ, Dunten PW, Bitinaite J, Horton NC Acta Crystallogr D Biol Crystallogr. 2011 Jan;67(Pt 1):67-74. Epub 2010, Dec 16. PMID:21206063^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.