TABLE 2.
Growth of auxotrophic stkB mutants on peptides and inhibition by tri-l-ornithinea
| Compound | Zone of inhibition or growth (mm)
|
|||||
|---|---|---|---|---|---|---|
| TK2420 | stkB1 (oppB R191P) | stkB2 (oppB R191G) | stkB3 (oppC R202S) | stkB4 (oppC R202C) | Δ(oppA-C)::kan | |
| Orn-Orn-Orn | 9 | 0 | 9 | 4 | 8 | 0 |
| Gly-His-Gly | 17 | 3 | 18 | 10 | 17 | 1 |
| Gly-Pro-Ala | 13 | 4.5 | 12 | 12 | 14 | 0 |
| Gly-Trp-Gly | 9 | 0 | 4 | 5 | 6 | 0 |
Strains were streaked on 115 mM K+ minimal glucose agar medium radially from a 6-mm disc containing 200 μg of tri-l-ornithine or 50 μg of the other peptides. The zone of inhibition by tri-l-ornithine or zone of growth produced by the other peptides is shown. Derivatives of the six strains, each auxotrophic for the italicized amino acid in the peptide, were used to test the ability of the other peptides to enter the cell. Auxotrophy for His was introduced by cotransduction with zee3129::Tn10, for Pro by cotransduction with zda::Tn10, and for Trp by introducing trpB83::Tn10 while retaining the stk or opp mutation. The auxotrophic derivatives of the strains all had very similar zones of growth (±1 mm) extending from discs containing 50 μg of the free amino acid.