3MQ6

Domain swapped SgrAI with DNA and calcium bound

Summary for 3MQ6

• Entry DOI: 10.2210/pdb3mq6/pdb
• Related: 3DPG 3DVO 3DW9
• Descriptor: SgraIR restriction enzyme, DNA (5'-D(*AP*AP*GP*TP*CP*CP*AP*CP*CP*GP*GP*TP*GP*GP*AP*CP*T)-3'), CALCIUM ION, ... (4 entities in total)
• Functional Keywords: restriction enzyme-dna complex, hydrolase-dna complex, domain swapping, hydrolase/dna
• Biological source: Streptomyces griseus; More
• Total number of polymer chains: 16
• Total formula weight: 346116.05

Authors

Dunten, P.W.,Horton, N.C.,Little, E.J. (deposition date: 2010-04-27, release date: 2010-11-10, Last modification date: 2024-02-21)

Primary citation

Park, C.K.,Joshi, H.K.,Agrawal, A.,Ghare, M.I.,Little, E.J.,Dunten, P.W.,Bitinaite, J.,Horton, N.C.
Domain swapping in allosteric modulation of DNA specificity.
Plos Biol., 8:e1000554-e1000554, 2010

PubMed Abstract: SgrAI is a type IIF restriction endonuclease that cuts an unusually long recognition sequence and exhibits allosteric self-modulation of cleavage activity and sequence specificity. Previous studies have shown that DNA bound dimers of SgrAI oligomerize into an activated form with higher DNA cleavage rates, although previously determined crystal structures of SgrAI bound to DNA show only the DNA bound dimer. A new crystal structure of the type II restriction endonuclease SgrAI bound to DNA and Ca(2+) is now presented, which shows the close association of two DNA bound SgrAI dimers. This tetrameric form is unlike those of the homologous enzymes Cfr10I and NgoMIV and is formed by the swapping of the amino-terminal 24 amino acid residues. Two mutations predicted to destabilize the swapped form of SgrAI, P27W and P27G, have been made and shown to eliminate both the oligomerization of the DNA bound SgrAI dimers as well as the allosteric stimulation of DNA cleavage by SgrAI. A mechanism involving domain swapping is proposed to explain the unusual allosteric properties of SgrAI via association of the domain swapped tetramer of SgrAI bound to DNA into higher order oligomers.

PubMed: 21151881
DOI: 10.1371/journal.pbio.1000554

Experimental method

X-RAY DIFFRACTION (2 Å)