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Ozdemir AY, Rusanov T, Kent T, Siddique LA, Pomerantz RT
Polymerase theta-helicase efficiently unwinds DNA and RNA-DNA hybrids
J Biol Chem (2018) 293:5259-5269.
POLQ is a unique multifunctional replication and repair gene that encodes for a N-terminal superfamily 2 helicase and a C-terminal A-family polymerase. Although the function of the polymerase domain has been investigated, little is understood regarding the helicase domain. Multiple studies have reported that Polq-helicase is unable to unwind DNA. However, it exhibits ATPase activity that is stimulated by single-strand DNA which presents a biochemical conundrum. In contrast to previous reports, we demonstrate that Polq-helicase (residues 1-894) efficiently unwinds DNA with 3'-5' polarity, including DNA with 3' or 5' overhangs, blunt-ended DNA, and replication forks. Polq-helicase also efficiently unwinds RNA-DNA hybrids, and exhibits a preference for unwinding the lagging strand at replication forks, similar to related HELQ helicase. Finally, we find that Polq-helicase can facilitate strand displacement synthesis by Polq-polymerase, suggesting a plausible function for the helicase domain. Taken together, these findings indicate nucleic acid unwinding as a relevant activity for Polq in replication repair.
Publication Date: 2018-04-06.
PMCID: PMC5892577
Last updated on Sunday, July 12, 2020