Cryo-EM structure and evolutionary history of the conjugation surface exclusion protein TraT

Seddon, C.; David, S.; Wong, J. L. C.; Ishimoto, N.; Bradshaw, J.; He, S.; Low, W. W.; Frankel, G.; Beis, K.

doi:10.1101/2024.08.09.607165

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bioRxiv · 10.1101/2024.08.09.607165

Cryo-EM structure and evolutionary history of the conjugation surface exclusion protein TraT

Seddon, C.·David, S.·Wong, J. L. C.·Ishimoto, N.·Bradshaw, J.·He, S.·Low, W. W.·Frankel, G.·Beis, K.

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Abstract

Conjugation plays a major role in dissemination of antimicrobial resistance genes. Following transfer of IncF-like plasmids, recipients become refractory to a second wave of conjugation with the same plasmid via entry (TraS) and surface (TraT) exclusion mechanisms. Here, we show that TraT from the pKpQIL and F plasmids (TraTpKpQIL and TraTF) exhibits plasmid surface exclusion specificity. The cryo-EM structures of TraTpKpQIL and TraTF revealed that they oligomerise into decameric champagne bottle cork-like structures, which are anchored to the outer membrane via a diacylglycerol modified -helical barrel domain. Unexpectedly, we identified chromosomal TraT homologues from multiple Gram-negative phyla which formed numerous deep-branching lineages in a phylogenetic tree of TraT sequences. Plasmid-associated TraT sequences largely cluster into two separate lineages that have more recently evolved, incorporating TraT from Enterobacterales IncF and Legionellaceae F-like plasmids. These findings suggest that different plasmid backbones have acquired and co-opted TraT on independent occasions.

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Seddon, C., David, S., Wong, J. L. C., Ishimoto, N., Bradshaw, J., He, S., Low, W. W., Frankel, G., Beis, K.. 2024-08-09. Cryo-EM structure and evolutionary history of the conjugation surface exclusion protein TraT. https://doi.org/10.1101/2024.08.09.607165

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