TABLE 3.
Genes and proteins involved in the synthesis of secretion systems in selected rhizobial genomesa
| Secretion system and characteristic | No. of ORFs and genes linked to the formation of secretion systems in strainb:
|
|||||
|---|---|---|---|---|---|---|
| NGR234 | 3841 | 1021 | 110* | 42 | 99 | |
| Type I | ||||||
| AprD/E | 2 | 8 | 5 | 2 | 2 | 4 |
| TolC | 1 | 1 | 1 | 1 | ||
| PrtD | 1 | 1 | 1 | 1 | 1 | |
| PrtE, HlyD family | 1 | 1 | 1 | 1 | 1 | |
| Type I protein | 1 | 1 | 1 | |||
| Type II | ||||||
| Gsp (general secretion pathway) | 13 | 8 | 11 | |||
| Sec pathway | 7 | 12 | 5 | 5 | 7 | 7 |
| Type III (Hrp, Rhc) | ||||||
| Rhc pili | 42 | 21 | 21 | 21 | ||
| Type IV | ||||||
| F-type (conjugation, Vir, Trb) | 23 | 10 | 10 | 13 | 31 | 19 |
| P-type (Flp and attachment) | 35 | 10 | 17 | 11 | 10 | 9 |
| Type V | ||||||
| Autotransporter (Aut) | 3 | 2 | 2 | 1 | ||
| TAT (twin arginine), TatA/B/C | 3 | 3 | 3 | 3 | 3 | 3 |
| SRP | 3 | 3 | 3 | 3 | 3 | 3 |
| Total | 132 | 52 | 49 | 70 | 78 | 81 |
Data for the analysis were extracted from the respective genome projects and the corresponding GenBank files. Column subheadings: NGR234, Rhizobium sp. strain NGR234; 3841, R. leguminosarum bv. viciae 3841 (48, 94); 1021, S. meliloti strain 1021 (30); 110, B. japonicum strain USDA110 (44); 42, R. etli strain CFN42 (32); 99, M. loti strain MAFF303099 (43).
*, B. japonicum sp. strain BTAi1 (NC_009485 and NC_009475) and B. japonicum sp. strain ORS278 (NC_009445) each carry 21 gsp genes (31). The data indicate the absolute number of ORFs identified in the genome linked to a particular secretion system. Genes identified in NGR234 are listed in Table S2 in the supplemental material, together with the respective ORF designations. Flagellum genes were not included in the analysis, and no ncRNAs were included in the SRP analysis.