9F12

CryoEM structure of the F plasmid relaxosome with oriT DNA ss-27_-3ds-2_+143 and TraI its TE mode, derived from ss-27_-3ds-2_+143-R Locally-refined 3.42 A Map.

Summary for 9F12

• Entry DOI: 10.2210/pdb9f12/pdb
• EMDB information: 50101 50122
• Descriptor: T-strand DNA (96-MER), R-strand DNA (85-MER), Integration host factor subunit alpha, ... (7 entities in total)
• Functional Keywords: relaxosome, bacterial conjugation, dna processing, relaxase, dna binding proteins, dna binding protein
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 8
• Total formula weight: 357999.84

Authors

Williams, S.M.,Waksman, G. (deposition date: 2024-04-17, release date: 2025-06-04)

Primary citation

Williams, S.M.,Raffl, S.,Kienesberger, S.,Ilangovan, A.,Zechner, E.L.,Waksman, G.
Cryo-EM Structure of the relaxosome, a complex essential for bacterial mating and the spread of antibiotic resistance genes.
Nat Commun, 16:4906-4906, 2025

PubMed Abstract: Bacterial mating, or conjugation, was discovered nearly 80 years ago as a process transferring genes from one bacterial cell (the donor) to another (the recipient). It requires three key multiprotein complexes in the donor cell: a DNA-processing machinery called the relaxosome, a double-membrane spanning type 4 secretion system (T4SS), and an extracellular appendage termed pilus. While the near-atomic resolution structures of the T4SS and pilus are already known, that of the relaxosome has not been reported to date. Here, we describe the cryo-EM structure of the fully assembled relaxosome encoded by the paradigm F plasmid in two different states corresponding to distinct functional steps along the DNA processing reaction. By varying the structures of model DNAs we delineate conformational changes required to initiate conjugation. Mutational studies of the various protein-protein and protein-DNA interaction hubs suggest a complex sensitive to trigger signals, that could arise from cell-to-cell contacts with recipient cells.

PubMed: 40425557
DOI: 10.1038/s41467-025-60116-6

Experimental method

ELECTRON MICROSCOPY (3.42 Å)