4C3G

cryo-EM structure of activated and oligomeric restriction endonuclease SgrAI

Summary for 4C3G

• Entry DOI: 10.2210/pdb4c3g/pdb
• EMDB information: 2441
• Descriptor: SGRAIR RESTRICTION ENZYME, 5'-D(*GP*AP*TP*GP*CP*GP*TP*GP*GP*GP*TP*CP*TP*TP *CP*AP*CP*AP)-3', 5'-D(*CP*CP*GP*GP*TP*GP*TP*GP*AP*AP*GP*AP*CP*CP *CP*AP*CP*GP*CP*AP*TP*CP)-3' (3 entities in total)
• Functional Keywords: hydrolase, restriction endonuclease, allostery, dna cleavage, parasite-host interaction
• Biological source: STREPTOMYCES GRISEUS; More
• Total number of polymer chains: 6
• Total formula weight: 100309.57

Authors

Lyumkis, D.,Talley, H.,Stewart, A.,Shah, S.,Park, C.K.,Tama, F.,Potter, C.S.,Carragher, B.,Horton, N.C. (deposition date: 2013-08-23, release date: 2013-09-11, Last modification date: 2024-05-08)

Primary citation

Lyumkis, D.,Talley, H.,Stewart, A.,Shah, S.,Park, C.K.,Tama, F.,Potter, C.S.,Carragher, B.,Horton, N.C.
Allosteric Regulation of DNA Cleavage and Sequence-Specificity Through Run-on Oligomerization.
Structure, 21:1848-, 2013

PubMed Abstract: SgrAI is a sequence specific DNA endonuclease that functions through an unusual enzymatic mechanism that is allosterically activated 200- to 500-fold by effector DNA, with a concomitant expansion of its DNA sequence specificity. Using single-particle transmission electron microscopy to reconstruct distinct populations of SgrAI oligomers, we show that in the presence of allosteric, activating DNA, the enzyme forms regular, repeating helical structures characterized by the addition of DNA-binding dimeric SgrAI subunits in a run-on manner. We also present the structure of oligomeric SgrAI at 8.6 Å resolution, demonstrating the conformational state of SgrAI in its activated form. Activated and oligomeric SgrAI displays key protein-protein interactions near the helix axis between its N termini, as well as allosteric protein-DNA interactions that are required for enzymatic activation. The hybrid approach reveals an unusual mechanism of enzyme activation that explains SgrAI's oligomerization and allosteric behavior.

PubMed: 24055317
DOI: 10.1016/J.STR.2013.08.012

Experimental method

ELECTRON MICROSCOPY (8.6 Å)