title: Monomeric solution structure of the helicase-binding domain of Escherichia coli DnaG primase.
abstract: DnaG is the primase that lays down RNA primers on single-stranded DNA during bacterial DNA replication. The solution structure of the DnaB-helicase-binding C-terminal domain of Escherichia coli DnaG was determined by NMR spectroscopy at near-neutral pH. The structure is a rare fold that, besides occurring in DnaG C-terminal domains, has been described only for the N-terminal domain of DnaB. The C-terminal helix hairpin present in the DnaG C-terminal domain, however, is either less stable or absent in DnaB, as evidenced by high mobility of the C-terminal 35 residues in a construct comprising residues 1-171. The present structure identifies the previous crystal structure of the E. coli DnaG C-terminal domain as a domain-swapped dimer. It is also significantly different from the NMR structure reported for the corresponding domain of DnaG from the thermophile Bacillus stearothermophilus. NMR experiments showed that the DnaG C-terminal domain does not bind to residues 1-171 of the E. coli DnaB helicase with significant affinity.
authors.affiliation: Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Xun-Cheng
authors.initials: XC
authors.lastname: Su
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Schaeffer
authors.forename: Karin V
authors.initials: KV
authors.lastname: Loscha
authors.forename: Pamela H P
authors.initials: PH
authors.lastname: Gan
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Dixon
authors.forename: Gottfried
authors.initials: G
authors.lastname: Otting
mesh_terms: D000595:Amino Acid Sequence; D019915:DNA Primase; D019281:Dimerization; D053488:DnaB Helicases / Q000737:chemistry*; D004706:Endodeoxyribonucleases / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D005090:Exodeoxyribonucleases / Q000737:chemistry*; D001411:Geobacillus stearothermophilus / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
chemical_list: D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; D019915:DNA Primase; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C121791:dnaG protein, E coli; C506730:dnaB protein, E coli; D053488:DnaB Helicases