These proteins contain a P-loop and walker-B site for nucleotide binding. TraG is essential for DNA transfer in bacterial conjugation. These proteins are thought to mediate interactions between the DNA-processing (Dtr) and the mating pair formation (Mpf) systems [2]. The C-terminus of this domain interacts with the relaxosome component TraM via the latter's tetramerisation domain. TraD is a hexameric ring ATPase that forms the cytoplasmic face of the conjugative pore [3]. The family contains a number of different DNA transfer proteins [4].

1: Sequence and analysis of the 60 kb conjugative, bacteriocin-producing plasmid pMRC01 from Lactococcus lactis DPC3147 Dougherty BA, Hill C, Weidman JF, Richardson DR, Venter JC, Ross RP; Mol Microbiol 1998;29:1029-1038. PMID:9767571

2: TraG-like proteins of DNA transfer systems and of the Helicobacter pylori type IV secretion system: inner membrane gate for exported substrates? Schroder G, Krause S, Zechner EL, Traxler B, Yeo HJ, Lurz R, Waksman G, Lanka E; J Bacteriol 2002;184:2767-2779. PMID:11976307

3: Structural basis of specific TraD-TraM recognition during F plasmid-mediated bacterial conjugation. Lu J, Wong JJ, Edwards RA, Manchak J, Frost LS, Glover JN; Mol Microbiol. 2008;70:89-99. PMID:18717787

4: Interaction between the co-inherited TraG coupling protein and the TraJ membrane-associated protein of the H-plasmid conjugative DNA transfer system resembles chromosomal DNA translocases. Gunton JE, Gilmour MW, Baptista KP, Lawley TD, Taylor DE; Microbiology. 2007;153:428-441. PMID:17259614