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From Proteopedia
Crystal structure of Pif1 helicase from Candida albicans
Structural highlights
FunctionPIF1_CANAL DNA-dependent ATPase and 5'-3' DNA helicase required for the maintenance of both mitochondrial and nuclear genome stability. Efficiently unwinds G-quadruplex (G4) DNA structures and forked RNA-DNA hybrids. Resolves G4 structures, preventing replication pausing and double-strand breaks (DSBs) at G4 motifs. Involved in the maintenance of telomeric DNA. Inhibits telomere elongation, de novo telomere formation and telomere addition to DSBs via catalytic inhibition of telomerase. Reduces the processivity of telomerase by displacing active telomerase from DNA ends. Releases telomerase by unwinding the short telomerase RNA/telomeric DNA hybrid that is the intermediate in the telomerase reaction. Involved in the maintenance of ribosomal (rDNA). Required for efficient fork arrest at the replication fork barrier within rDNA. Involved in the maintenance of mitochondrial (mtDNA). Required to maintain mtDNA under conditions that introduce dsDNA breaks in mtDNA, either preventing or repairing dsDNA breaks. May inhibit replication progression to allow time for repair. May have a general role in chromosomal replication by affecting Okazaki fragment maturation. May have a role in conjunction with DNA2 helicase/nuclease in 5'-flap extension during Okazaki fragment processing.[HAMAP-Rule:MF_03176] Publication Abstract from PubMedPif1 helicases, conserved in eukaryotes, are involved in maintaining genome stability in both the nucleus and mitochondria. Here, we report the crystal structure of a truncated Candida Albicans Pif1 (CaPif1(368-883)) in complex with ssDNA and an ATP analog. Our results show that the Q-motif is responsible for identifying adenine bases, and CaPif1 preferentially utilizes ATP/dATP during dsDNA unwinding. Although CaPif1 shares structural similarities with Saccharomyces cerevisiae Pif1, CaPif1 can contact the thymidine bases of DNA by hydrogen bonds, whereas ScPif1 cannot. More importantly, the crosslinking and mutant experiments have demonstrated that the conformational change of domain 2B is necessary for CaPif1 to unwind dsDNA. These findings contribute to further the understanding of the unwinding mechanism of Pif1. Structural study of the function of Candida Albicans Pif1.,Lu KY, Xin BG, Zhang T, Liu NN, Li D, Rety S, Xi XG Biochem Biophys Res Commun. 2021 Aug 27;567:190-194. doi: , 10.1016/j.bbrc.2021.06.050. Epub 2021 Jun 21. PMID:34166917[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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