TABLE 4.
Mapping of the entry exclusion locus of the Ti plasmid by using polar insertion mutations within the trb operon
| Recipienta | Relevant protein(s) expressed in recipient | Conjugation efficiencyb (SD) | Exclusion coefficientc |
|---|---|---|---|
| Recipients without trb mutations | |||
| R10(pPZP201) | None (vector control) | 0.90 (0.1) | 1 |
| R10(pHC335) | TraR, TraI, TraA to TraH, TrbB to TrbL | 0.006 (0.0007) | 150 |
| HC159(pYDH902)(pPZP201) | None | 0.11 (0.015) | 8.2 |
| HC159(pYDH902)(pHC335) | TraR, TraI, Trb | 0.0005 (0.00008) | 1800 |
| Recipients with trb genes mutated using transcriptionally polar insertion mutations | |||
| HC161(pHC335) | TraR, TrbBCD | 0.84 (0.1) | 1.07 |
| HC162(pHC335) | TraR, TrbBCDEJ | 0.19 (0.02) | 4.7 |
| HC163(pHC335) | TraR, TrbBCDEJK | 0.007 (0.001) | 129 |
| HC164(pHC335) | TraR, TrbBCDEJKLF | 0.007 (0.001) | 129 |
| Recipients with Trb proteins expressed from a multicopy plasmid via a tac promoter | |||
| R10(pHC012) | None (vector control) | 0.18 (0.02) | 1 |
| R10(pJZ381) | TraR, TraI, TraA to TraH, TrbB to TrbL | 0.0004 (0.0002) | 450 |
| R10(pHC364) | TrbBCDEJK | 0.008 (0.004) | 22.5 |
| R10(pHC361) | TrbJK | 0.0012 (0.0005) | 150 |
| R10(pHC368) | TrbK | 0.025 (0.006) | 7.2 |
a
The donor strain in each experiment was WCF5(pJZ358), which overexpresses TraR and has an octopine-type Ti plasmid marked with a Kmr determinant (6). Transconjugants were selected using the Kmr gene of the Ti plasmid and the Spr gene of pPZP201 or pHC335 (first eight lines) or using the Gmr gene of pHC012 and its derivatives (last four lines).
b
Number of transconjugants per donor.
c
The exclusion coefficient is the number of transconjugants per donor for the no-exclusion control (lines with exclusion coefficients of 1) divided by the number of transconjugants of the tested recipient strain per donor.