title: Interactions of bacteriophage T4-coded primase (gp61) with the T4 replication helicase (gp41) and DNA in primosome formation.
abstract: One primase (gp61) and six helicase (gp41) subunits interact to form the bacteriophage T4-coded primosome at the DNA replication fork. In order to map some of the detailed interactions of the primase within the primosome, we have constructed and characterized variants of the gp61 primase that carry kinase tags at either the N or the C terminus of the polypeptide chain. These tagged gp61 constructs have been probed using several analytical methods. Proteolytic digestion and protein kinase protection experiments show that specific interactions with single-stranded DNA and the T4 helicase hexamer significantly protect both the N- and the C-terminal regions of the T4 primase polypeptide chain against modification by these procedures and that this protection becomes more pronounced when the primase is assembled within the complete ternary primosome complex. Additional discrete sites of both protection and apparent hypersensitivity along the gp61 polypeptide chain have also been mapped by proteolytic footprinting reactions for the binary helicase-primase complex and in the three component primosome. These studies provide a detailed map of a number of gp61 contact positions within the primosome and reveal interactions that may be important in the structure and function of this central component of the T4 DNA replication complex.
authors.affiliation: Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene, Oregon 97403, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Jing
authors.forename: F
authors.initials: F
authors.lastname: Dong
authors.forename: G J
authors.initials: GJ
authors.lastname: Latham
authors.forename: P H
authors.initials: PH
authors.lastname: von Hippel
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D017122:Bacteriophage T4 / Q000201:enzymology / Q000235:genetics*; D004265:DNA Helicases / Q000378:metabolism*; D019915:DNA Primase / Q000737:chemistry / Q000378:metabolism*; D017931:DNA Primers / Q000378:metabolism; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis*; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli; D008666:Metalloendopeptidases; D010449:Peptide Mapping; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D004279:DNA, Viral; D014764:Viral Proteins; C063983:gene 41 protein, Enterobacteria phage T4; D019915:DNA Primase; D010450:Endopeptidases; D008666:Metalloendopeptidases; C058921:endoproteinase Asp-N; D000251:Adenosine Triphosphatases; D004265:DNA Helicases