6s3m

Crystal structure of helicase Pif1 from Thermus oshimai in complex with ssDNA (dT)18 and ADP-AlF4

spinqualitylabelsall models 6s3m, resolution 2.11Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6s3m is a 4 chain structure with sequence from Thermus oshimai. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.113Å Ligands: ADP, ALF, MG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function K7RJ88_THEOS Publication Abstract from PubMed Pif1 is an SF1B helicase that is evolutionarily conserved from bacteria to humans and plays multiple roles in maintaining genome stability in both nucleus and mitochondria. Though highly conserved, Pif1 family harbors a large mechanistic diversity. Here, we report crystal structures of Thermus oshimai Pif1 (ToPif1) alone and complexed with partial duplex or single-stranded DNA. In the apo state and in complex with a partial duplex DNA, ToPif1 is monomeric with its domain 2B/loop3 adopting a closed and an open conformation, respectively. When complexed with a single-stranded DNA, ToPif1 forms a stable dimer with domain 2B/loop3 shifting to a more open conformation. Single-molecule and biochemical assays show that domain 2B/loop3 switches repetitively between the closed and open conformations when a ToPif1 monomer unwinds DNA and, in contrast with other typical dimeric SF1A helicases, dimerization has an inhibitory effect on its helicase activity. This mechanism is not general for all Pif1 helicases but illustrates the diversity of regulation mechanisms among different helicases. It also raises the possibility that although dimerization results in activation for SF1A helicases, it may lead to inhibition for some of the other uncharacterized SF1B helicases, an interesting subject warranting further studies. Structural and functional studies of SF1B Pif1 from Thermus oshimai reveal dimerization-induced helicase inhibition.,Dai YX, Chen WF, Liu NN, Teng FY, Guo HL, Hou XM, Dou SX, Rety S, Xi XG Nucleic Acids Res. 2021 Mar 30. pii: 6204648. doi: 10.1093/nar/gkab188. PMID:33784404 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Helicase 3D structures

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