Conjugative transfer of the IncN plasmid pKM101 is mediated by dynamic interactions between the TraK accessory factor and TraI relaxase.

ABSTRACT: Conjugative dissemination of mobile genetic elements (MGEs) among bacteria is initiated by assembly of the relaxosome at the MGE's origin-of-transfer (oriT) sequence. A critical but poorly defined step of relaxosome assembly involves recruitment of the catalytic relaxase to its DNA strand-specific nicking site within oriT. Here, we present evidence by AlphaFold modeling, affinity pulldowns, and in vivo site-directed photocrosslinking that the TraK Ribbon-Helix-Helix DNA-binding protein recruits TraI to oriT through a dynamic interaction in which TraI's C-terminal unstructured domain (TraI_CTD) wraps around TraK's C-proximal tetramerization domain. Upon relaxosome assembly, conformational changes disrupt this contact, and TraI_CTD instead self-associates as a prerequisit

SUBMITTER: Li YG 

PROVIDER: S-EPMC11560498 | biostudies-literature | 2024 Nov

REPOSITORIES: biostudies-literature