RT Journal Article SR Electronic T1 The DNA replication initiation protein DnaD is recruited to a specific strand of the Bacillus subtilis chromosome origin JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.04.18.488654 DO 10.1101/2022.04.18.488654 A1 Charles Winterhalter A1 Simone Pelliciari A1 Daniel Stevens A1 Stepan Fenyk A1 Elie Marchand A1 Nora B Cronin A1 Panos Soultanas A1 Tiago R. D. Costa A1 Aravindan Ilangovan A1 Heath Murray YR 2022 UL http://biorxiv.org/content/early/2022/04/18/2022.04.18.488654.abstract AB Genome replication is a fundamental biological activity shared by all organisms. Chromosomal replication proceeds bidirectionally from origins, requiring the loading of two helicases, one for each replisome. The molecular mechanisms for helicase loading at bacterial chromosome origins (oriC) are unclear. Here we investigated the essential DNA replication initiation protein DnaD in the model organism Bacillus subtilis. A set of DnaD residues required for ssDNA binding was identified, and photo-crosslinking revealed that this ssDNA binding region interacts preferentially with one strand of oriC. Biochemical and genetic data support the model that DnaD recognizes a new single-stranded DNA (ssDNA) motif located in oriC (DnaD Recognition Element, “DRE”). Considered with cryo-electron microscopy (cryo-EM) imaging of full length DnaD, we propose that the location of the DRE within the oriC orchestrates strand-specific recruitment of helicase to achieve bidirectional DNA replication. These findings significantly advance our mechanistic understanding of bidirectional replication from a bacterial chromosome origin.Competing Interest StatementThe authors have declared no competing interest.