Structural highlights
FunctionVE1_BPV1 ATP-dependent DNA helicase required for initiation of viral DNA replication. It forms a complex with the viral E2 protein. The E1-E2 complex binds to the replication origin which contains binding sites for both proteins. Publication Abstract from PubMedHexameric helicases are motor proteins that unwind double-stranded DNA (dsDNA) during DNA replication but how they are optimised for strand separation is unclear. Here we present the cryo-EM structure of the full-length E1 helicase from papillomavirus, revealing all arms of a bound DNA replication fork and their interactions with the helicase. The replication fork junction is located at the entrance to the helicase collar ring, that sits above the AAA + motor assembly. dsDNA is escorted to and the 5 single-stranded DNA (ssDNA) away from the unwinding point by the E1 dsDNA origin binding domains. The 3 ssDNA interacts with six spirally-arranged beta-hairpins and their cyclical top-to-bottom movement pulls the ssDNA through the helicase. Pulling of the RF against the collar ring separates the base-pairs, while modelling of the conformational cycle suggest an accompanying movement of the collar ring has an auxiliary role, helping to make efficient use of ATP in duplex unwinding. Unwinding of a DNA replication fork by a hexameric viral helicase.,Javed A, Major B, Stead JA, Sanders CM, Orlova EV Nat Commun. 2021 Sep 20;12(1):5535. doi: 10.1038/s41467-021-25843-6. PMID:34545080[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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