TABLE 4.
Effect of the presence of cysteine, methionine, or homocysteine in the growth medium on the expression of several S. mutans genesa
| Gene | Organizationb | Mean ratio ± SD of gene expression levels in cells grown in:
|
||
|---|---|---|---|---|
| CDM+M-thiosulfate vs CDM+CM-thiosulfate | CDM+C vs CDM+CM | CDM+CM-homocysteine vs CDM+CMc | ||
| metE | metEF | 1.4 ± 0.02 | 39.4 ± 4.1 | 38 ± 7.3 |
| smu.1487 | smu.1487 | 1.7 ± 0.09 | 13.1 ± 2.0 | 15.7 ± 1.8 |
| atmB | atmBCDE-cnhA-smu.1936c-smu.1935c-smu.1934c-smu.1933c | 1.1 ± 0.17 | 3.1 ± 0.6 | 3.9 ± 0.1 |
| smu.1936c | atmBCDE-cnhA-smu.1936c-smu.1935c-smu.1934c-smu.1933c | 1.7 ± 0.15 | 2.5 ± 0.4 | 2.3 ± 0.3 |
| cysD | pcrA-cysD | 1.3 ± 0.17 | 1.3 ± 0.02 | 1.7 ± 0.1 |
| metA | apt-metA | 1.4 ± 0.16 | 1.3 ± 0.1 | 1.0 ± 0.1 |
| metR | metR | 1.4 ± 0.09 | 0.7 ± 0.03 | 1.1 ± 0.1 |
a
Gene expression in the S. mutans wild-type strain was evaluated by real-time QRT-PCR.
b
Gene clusters were deduced from a sequence analysis and transcriptional start site mapping (Fig. 3).
c
The effect of homocysteine on gene expression was evaluated 45 min after the addition of 4 mM homocysteine to exponentially growing cells (OD600 of 0.2).