Structural basis of specific TraD-TraM recognition during F plasmid-mediated bacterial conjugation.
F plasmid-mediated bacterial conjugation requires interactions between a relaxosome component, TraM, and the coupling protein TraD, a hexameric ring ATPase that forms the cytoplasmic face of the conjugative pore. Here we present the crystal structure of the C-terminal tail of TraD bound to the TraM tetramerization domain, the first structural evidence of relaxosome-coupling protein interactions. The structure reveals the TraD C-terminal peptide bound to each of four symmetry-related grooves on the surface of the TraM tetramer. Extensive protein-protein interactions were observed between the two proteins. Mutational analysis indicates that these interactions are specific and required for efficient F conjugation in vivo. Our results suggest that specific interactions between the C-terminal tail of TraD and the TraM tetramerization domain might lead to more generalized interactions that stabilize the relaxosome-coupling protein complex in preparation for conjugative DNA transfer.
Lu
Jun
J
Departments of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
Wong
Joyce J W
JJ
Edwards
Ross A
RA
Manchak
Jan
J
Frost
Laura S
LS
Glover
J N Mark
JN
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics*; D005144:F Factor / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D054730:Protein Interaction Domains and Motifs; D016415:Sequence Alignment
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C064957:traD protein, E coli; C074281:TraM protein, bacterial