TABLE 2.
Membrane topology predictions for VirB4 proteinsa
| Family or source | Protein | Organism | Predicted transmembrane region | Size (aa) |
|---|---|---|---|---|
| PilF/PilH | TrhC R27 | Salmonella enterica serovar Typhi | No | 887 |
| TraC F | Escherichia coli | No | 875 | |
| TraC R100 | E. coli | No | 876 | |
| TrbE family | TrbE RP4 (IncP) | E. coli | Yes (2) | 852 |
| TrbE pTi | Agrobacterium tumefaciens | No | 822 | |
| LvhB4 | Legionella pneumophila | No | 826 | |
| VirB4 | Caulobacter crescentus | No | 794 | |
| Tol plasmids, Xanthomonas | MpfC | Pseudomonas putida | No | 894 |
| VirB4 pXcB | Xanthomonas citri | No | 877 | |
| VirB4 | Wolbachia endosymbiont | No | 801 | |
| VirB4 | Rickettsia felis | No | 810 | |
| Agrobacterium VirB4 | VirB4 | A. tumefaciens | No | 789 |
| VirB4 p42D | Rhizobium etli | No | 795 | |
| VirB4 pSYMA | Sinorhizobium meliloti | No | 792 | |
| VirB4 | Bartonella henselae | No | 784 | |
| PilW/PilN | TraB pKM101 | E. coli | No | 866 |
| TrwK R388 | E. coli | No | 823 | |
| TrwK | Bartonella quintana | No | 823 | |
| PilX, Helicobacter | CagE | Helicobacter pylori | Yes (2) | 981 |
| VirB4 pCL46 | Campylobacter lari | Yes (1) | 924 | |
| CmgB3/4 | Campylobacter jejuni | Yes (1) | 922 | |
| TriC | Yersinia enterocolitica | Yes (2) | 915 | |
| VirB4 pCRY | Yersinia pestis | Yes (1) | 894 | |
| PilX3/4 R6K | E. coli | Yes (1) | 919 | |
| Brucella and cryptic plasmids from soil | PtlC | Bordetella pertussis | No | 824 |
| TraC pIPO2T | No | 826 | ||
| VirB4 | Brucella suis | No | 831 | |
| VirB4 | Xanthomonas campestris | No | 817 | |
| VirB4 | Dichelobacter nodosus | No | 796 | |
| VirB4 pXF51 | Xylella fastidiosa | No | 815 | |
| TraE pF3028 | Haemophilus influenzae | No | 807 |
a
Amino acid sequences of representative members of widely separated branches of the VirB4 phylogenetic tree analyzed by transmembrane-predicting programs (Sosui, HMMTOP, DAS, TMHMM, and TopPred). DNA sequencing of the intergenic region between PilX3 and PilX4 has revealed that both proteins are fused together in plasmid R6K (unpublished data). Proteins listed below those of a given family but separated from them by a space are evolutionarily close to that family but not members of it.