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Mitochondrial helicase Irc3 translocates along double‐stranded DNA
Author(s) -
Sedman Tiina,
Garber Natalja,
Gaidutšik Ilja,
Sillamaa Sirelin,
Paats Joosep,
Piljukov Vlad J.,
Sedman Juhan
Publication year - 2017
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 - 10.1002/1873-3468.12903
Subject(s) - helicase , translocase , dna , atp hydrolysis , mitochondrial dna , primase , biology , rna helicase a , biochemistry , biophysics , chemistry , atpase , enzyme , gene , rna , reverse transcriptase , chromosomal translocation
Irc3 is a superfamily II helicase required for mitochondrial DNA stability in Saccharomyces cerevisiae . Irc3 remodels branched DNA structures, including substrates without extensive single‐stranded regions. Therefore, it is unlikely that Irc3 uses the conventional single‐stranded DNA translocase mechanism utilized by most helicases. Here, we demonstrate that Irc3 disrupts partially triple‐stranded DNA structures in an ATP ‐dependent manner. Our kinetic experiments indicate that the rate of ATP hydrolysis by Irc3 is dependent on the length of the double‐stranded DNA cosubstrate. Furthermore, the previously uncharacterized C‐terminal region of Irc3 is essential for these two characteristic features and forms a high affinity complex with branched DNA . Together, our experiments demonstrate that Irc3 has double‐stranded DNA translocase activity.