Table 2.
mRNA folding energies of the AGGAGG ribosome binding site and activities of secreted α-amylase of selected clones from the Usp45TM8 silent mutation librarya
| Usp45TM8 silent mutation clone | ΔG of ribosome binding site (AGGAGG) | Secreted α-amylase activity (% of Usp45sp)b |
|---|---|---|
| Usp45TM8_SM15 | −8.2 | 135 ± 2 |
| Usp45TM8_SM7 | −6.1 | 137 ± 6 |
| Usp45TM8_SM22 | −6.1 | 140 ± 2 |
| Usp45TM8_SM25 | −6.1 | 151 ± 3 |
| Usp45TM8_SM9 | −3.3 | 145 ± 5 |
| Usp45TM8_SM10 | −3.0 | 143 ± 9 |
| Usp45TM8_SM14 | −3.0 | 147 ± 5 |
| Usp45TM8 | −2.1 | 145 ± 10 |
a
α-Amylase secretion levels are reported for cultures induced with 10 ng/ml nisin for 2 h at mid-log phase. ΔG, mRNA folding energy. Nucleotide sequences are given in Table S6 in the supplemental material.
b
α-Amylase secretion data represent the means ± SEM of the results of three independent experiments. For each value in this column, P < 0.01 (for statistical comparison of α-amylase activities of the respective clone and Usp45sp using one-tailed Student's t test).