6is8

Publication Abstract from PubMed

The Holliday junction (HJ) is a key intermediate during homologous recombination and DNA double-strand break repair. Timely HJ resolution by resolvases is critical for maintaining genome stability. The mechanisms underlying sequence-specific substrate recognition and cleavage by resolvases remain elusive. The monokaryotic chloroplast 1 protein (MOC1) specifically cleaves four-way DNA junctions in a sequence-specific manner. Here, we report the crystal structures of MOC1 from Zea mays, alone or bound to HJ DNA. MOC1 uses a unique beta-hairpin to embrace the DNA junction. A base-recognition motif specifically interacts with the junction center, inducing base flipping and pseudobase-pair formation at the strand-exchanging points. Structures of MOC1 bound to HJ and different metal ions support a two-metal ion catalysis mechanism. Further molecular dynamics simulations and biochemical analyses reveal a communication between specific substrate recognition and metal ion-dependent catalysis. Our study thus provides a mechanism for how a resolvase turns substrate specificity into catalytic efficiency.

Structural basis of sequence-specific Holliday junction cleavage by MOC1.,Lin H, Zhang D, Zuo K, Yuan C, Li J, Huang M, Lin Z Nat Chem Biol. 2019 Oct 14. pii: 10.1038/s41589-019-0377-4. doi:, 10.1038/s41589-019-0377-4. PMID:31611704^[1]

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