Download MendeleyStructural insights into single-stranded DNA binding and cleavage by F factor TraI.
Datta, S., Larkin, C., Schildbach, J.F.(2003) Structure 11: 1369-1379
- PubMed: 14604527
- DOI: https://doi.org/10.1016/j.str.2003.10.001
- Primary Citation of Related Structures:
1P4D - PubMed Abstract:
Conjugative plasmid transfer between bacteria disseminates antibiotic resistance and diversifies prokaryotic genomes. Relaxases, proteins essential for conjugation, cleave one plasmid strand sequence specifically prior to transfer. Cleavage occurs through a Mg(2+)-dependent transesterification involving a tyrosyl hydroxyl and a DNA phosphate. The structure of the F plasmid TraI relaxase domain, described here, is a five-strand beta sheet flanked by alpha helices. The protein resembles replication initiator protein AAV-5 Rep but is circularly permuted, yielding a different topology. The beta sheet forms a binding cleft lined with neutral, nonaromatic residues, unlike most single-stranded DNA binding proteins which use aromatic and charged residues. The cleft contains depressions, suggesting base recognition occurs in a knob-into-hole fashion. Unlike most nucleases, three histidines but no acidic residues coordinate a Mg(2+) located near the catalytic tyrosine. The full positive charge on the Mg(2+) and the architecture of the active site suggest multiple roles for Mg(2+) in DNA cleavage.
Organizational Affiliation:
Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA.
