Year: 2026
Type: article
Abstract: Ring-shaped helicases must be opened and loaded onto DNA to initiate genome replication. In bacteria, most species lack canonical AAA+ helicase loaders and instead rely on DciA, an evolutionarily conserved, ATP-independent factor whose mechanism has remained unclear. Here we define how DciA remodels the bacterial replicative helicase DnaB. A 3.5 Å cryo-EM structure reveals a DnaB6·DciA3 complex in which DciA binds the periphery of the helicase and stabilizes a right-handed open-helical conformation with a single cracked interface. Three DciA molecules dock onto alternate linker-helix/docking-helix modules, while one N-terminal domain (NTD) engages the cracked interface, occupying the pocket vacated by the displaced linker helix and acting as a wedge to promote ring opening. Functional analyses reveal how DciA couples ATPase suppression with efficient helicase loading through coordinated actions of its NTDs and C-terminal domains. Together, these findings define a minimal, ATP-independent mechanism for helicase loading and show how an ancestral loader remodels DnaB to overcome a fundamental topological barrier.
Source: Nucleic Acids Research
DOI: 10.1093/nar/gkag977
Authors: Lidia Araújo-Bazán, Ernesto Arias-Palomo
Institution: Centro de Investigaciones Biológicas Margarita Salas
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $3,992
Awards: G1105844351, G1204740081, G1272900390, G1416831901, G1486913955, G1719462714, G280048558, G318412399, G3428307696, G348919436, G4033406476, G410571670, G451917667, G491712853, G4993905653, G5195188938, G523076202, G529962013, G5539308778, G554358111, G5635532810, G593054264, G5943232429, G5967599077, G6033112984, G631184005, G6502585861, G6520718613, G7395345766, G7805626310, G7863371703, G8497050386, G8568794117, G8667377315
OpenAlex ID: W7223563939