title: Bacterial initiators form dynamic filaments on single-stranded DNA monomer by monomer.
abstract: DNA replication initiation is mediated across all domains of life by initiator proteins oligomerizing at replication origins. Recently, it was shown that initiators can directly bind single-stranded DNA (ssDNA) and thus might enhance origin melting. In this study, we used single-molecule fluorescence assays to probe the ssDNA binding mechanism of the replication initiator DnaA. Our experiments revealed that DnaA forms a dynamic filament on ssDNA in 3' to 5' directionality in the presence of ATP and analogs. After nucleation with a three-monomer seed, monomers dynamically assemble and disassemble one monomer at a time at the 5' end, each monomer binding three nucleotides of ssDNA. The addition of adjacent double-stranded DnaA binding sites stabilized the DnaA filament on ssDNA. Our results extend the current models of origin melting via DnaA ssDNA interaction.
authors.affiliation: B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstraße 18, 01307 Dresden, Germany.
authors.forename: Hsin-Mei
authors.initials: HM
authors.lastname: Cheng
authors.affiliation: B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstraße 18, 01307 Dresden, Germany.
authors.forename: Philip
authors.initials: P
authors.lastname: Gröger
authors.affiliation: B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstraße 18, 01307 Dresden, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hartmann
authors.affiliation: B CUBE - Center for Molecular Bioengineering, Technische Universität Dresden, Arnoldstraße 18, 01307 Dresden, Germany schlierf@bcube-dresden.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Schlierf
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D011485:Protein Binding; D018741:Replication Origin
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria