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

Elizabeth J. Little, Pete W. Dunten, Jurate Bitinaite, Nancy C Horton

Research output: Contribution to journalArticle

8 Scopus citations


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 Mg2+ and bound to secondary-site DNA with either Mg2+ or Ca2+ 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 Ca2+ [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/Mg2+ 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.

Original languageEnglish (US)
Pages (from-to)67-74
Number of pages8
JournalActa Crystallographica Section D: Biological Crystallography
Issue number1
Publication statusPublished - Jan 2011



  • DNA cleavage
  • restriction endonucleases
  • SgrAI

ASJC Scopus subject areas

  • Structural Biology

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