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Irc3 is a monomeric DNA branch point‐binding helicase in mitochondria of the yeast Saccharomyces cerevisiae
Author(s) -
Piljukov Vlad–Julian,
Garber Natalja,
Sedman Tiina,
Sedman Juhan
Publication year - 2020
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13893
Subject(s) - helicase , saccharomyces cerevisiae , biochemistry , branch migration , dna , biology , dna clamp , coacervate , biophysics , yeast , chemistry , microbiology and biotechnology , homologous recombination , holliday junction , rna , gene , reverse transcriptase
Irc3 is a superfamily II DNA helicase required for the maintenance of mitochondrial DNA stability in Saccharomyces cerevisiae . Here, we show that recombinant Irc3 is a monomeric protein and that it can form a binary complex with forked DNA. The catalytically active enzyme is a monomer as no positive cooperativity of ATP hydrolysis or DNA unwinding can be detected. Interestingly, we find that Irc3 prefers to unwind the nascent lagging strand at a replication fork. Using DNase I footprinting, we demonstrate that Irc3 captures DNA substrates by establishing a strong contact at the DNA branching point. Additional protections on the lagging strand template suggest a 3′‐to‐5′ polarity for Irc3 movement.