Unique Helicase Determinants in the Essential Conjugative TraI Factor from Salmonella enterica Serovar Typhimurium Plasmid pCU1

摘要: The widespread development of multidrug-resistant bacteria is a major health emergency. Conjugative DNA plasmids, which harbor wide range antibiotic resistance genes, also encode the protein factors necessary to orchestrate propagation plasmid between bacterial cells through conjugative transfer. Successful transfer depends on key catalytic components nick one strand duplex and separate strands while cell-to-cell occurs. TraI from Salmonella pCU1 fulfills these roles, as it contains both single-stranded DNA-nicking relaxase ATP-dependent helicase domains within single, 1,078-residue polypeptide. In this work, we unraveled determinants binding, ATPase, separation assays. binds substrates with high affinity in manner influenced by nucleic acid length presence hairpin structure adjacent site. selectively hydrolyzes ATP, mutations conserved motifs eliminate ATPase activity. Surprisingly, absence relatively short (144-residue) domain at extreme C terminus severely diminishes separation. Collectively, data define factor reveal previously uncharacterized C-terminal functional that uncouples ATP hydrolysis