TABLE 1.
orn and aftA genotypes, embC expression, and ethambutol MICs in large- and small-colony variants of M. tuberculosisa
| Strain | orn gene | aftA gene | embC expression (fold change compared to 210)b | Colony morphology | EMB MIC (μg/ml)c | No. of passages to reversion |
|---|---|---|---|---|---|---|
| 210 | WT (active) | WT | 1 | Large | 2 | NA |
| 210-ornInsC | Frameshift (inactive) | WT | 1 | Small | 2 | >20 |
| 16C1 | WT (active) | Leu198Leu | 5 | Large | 8 | NA |
| 16C1-ornInsC | Frameshift (inactive) | Leu198Leu | 27 | Small | 32 | 8 ± 1 |
| 24C1 | Frameshift (inactive) | Leu198Leu | 27 | Small | 32 | 4 ± 1 |
| BC8 | MT (active) | Leu198Leu | 8 | Large | 8 | NA |
| 16C1Δcas | WT (active) | Leu198Leu | ND | Large | 8 | NA |
| 24C1Δcas | Frameshift (inactive) | Leu198Leu | ND | Small | 32 | 6 ± 1 |
a
WT, wild-type; MT, mutant; EMB, ethambutol; NA, not applicable; ND, not done.
b
embC expression was determined by three independent RNA-seq experiments (Table S4).
c
All MICs were determined in triplicate (Table S3). Because each value within a triplicate MIC test was similar to the other values, a single MIC is shown without standard deviation.