title: The structure of a DnaB-family replicative helicase and its interactions with primase.
abstract: Helicases are essential enzymes for DNA replication, a fundamental process in all living organisms. The DnaB family are hexameric replicative helicases that unwind duplex DNA and coordinate with RNA primase and other proteins at the replication fork in prokaryotes. Here, we report the full-length crystal structure of G40P, a DnaB family helicase. The hexamer complex reveals an unusual architectural feature and a new type of assembly mechanism. The hexamer has two tiers: a three-fold symmetric N-terminal tier and a six-fold symmetric C-terminal tier. Monomers with two different conformations, termed cis and trans, come together to provide a topological solution for the dual symmetry within a hexamer. Structure-guided mutational studies indicate an important role for the N-terminal tier in binding primase and regulating primase-mediated stimulation of helicase activity. This study provides insights into the structural and functional interplay between G40P helicase and DnaG primase.
authors.affiliation: Molecular and Computational Biology, University of Southern California, 1050 Childs Way, Los Angeles, California 90089, USA.
authors.forename: Ganggang
authors.initials: G
authors.lastname: Wang
authors.forename: Michael G
authors.initials: MG
authors.lastname: Klein
authors.forename: Etienne
authors.initials: E
authors.lastname: Tokonzaba
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lauren G
authors.initials: LG
authors.lastname: Holden
authors.forename: Xiaojiang S
authors.initials: XS
authors.lastname: Chen
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D001435:Bacteriophages / Q000201:enzymology / Q000235:genetics; D019915:DNA Primase / Q000737:chemistry* / Q000378:metabolism*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D053488:DnaB Helicases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011994:Recombinant Proteins; D014764:Viral Proteins; D019915:DNA Primase; D000251:Adenosine Triphosphatases; D053488:DnaB Helicases