tailieunhanh - Báo cáo khoa học: Monomeric solution structure of the helicase-binding domain of Escherichia coli DnaG primase

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 ofEscherichia coliDnaG 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. | ỊFEBS Journal Monomeric solution structure of the helicase-binding domain of Escherichia coli DnaG primase Xun-Cheng Su Patrick M. Schaeffer Karin V. Loscha Pamela H. P. Gan Nicholas E. Dixon and Gottfried Otting Research Schoolof Chemistry Australian National university Canberra Australia Keywords DnaB DnaG domain swap NMR structure primase Correspondence G. Otting Research School of Chemistry Australian NationalUniversity Canberra ACT 0200 Australia Fax 61 2 61250750 Tel 61 2 61256507 E-mail Database The NMR chemical shifts and coordinates of the structure have been submiited to the BioMagResBank accession code 6284 and Protein Data Bank accession code 2HAJ Received 28 July 2006 revised 7 September 2006 accepted 11 September 2006 doi 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. All organisms replicate DNA by copying one strand the leading strand in a continuous manner whereas the other DNA strand the lagging strand is replicated in