TABLE 1.
Plasmids used in this study
| Plasmid | Relevant genotype | Source or reference |
|---|---|---|
| pTZ19U | lacO+P+Z′ Ampr | Bio-Rad |
| pSUmelA | melA+melΔB Cmr | 51 |
| pKK223-3 | Ampr | Pharmacia Biotech |
| pKKMB | melΔ(A)B+ Ampr | 2 |
| pR52S | melΔ(A)B+(Arg-52→Ser) Ampr | This study |
| pR52V | melΔ(A)B+(Arg-52→Val) Ampr | This study |
| pR52Q | melΔ(A)B+(Arg-52→Gln) Ampr | This study |
| pR52Ka | melΔ(A)B+(Arg-52→Lys) Ampr | This study |
| pR52S/D19G | melΔ(A)B+(Arg-52→Ser, Asp-19→Gly) Ampr | This study |
| pR52S/D55N | melΔ(A)B+(Arg-52→Ser, Asp-55→Asn) Ampr | This study |
| pR52S/P60Q | melΔ(A)B+(Arg-52→Ser, Pro-60→Gln) Ampr | This study |
| pR52S/W116R | melΔ(A)B+(Arg-52→Ser, Trp-116→Arg) Ampr | This study |
| pR52S/N244S | melΔ(A)B+(Arg-52→Ser, Asn-244→Ser) Ampr | This study |
| pR52S/S247R | melΔ(A)B+(Arg-52→Ser, Ser-247→Arg) Ampr | This study |
| pR52S/N248K | melΔ(A)B+(Arg-52→Ser, Asn-248→Lys) Ampr | This study |
| pR52S/I352V | melΔ(A)B+(Arg-52→Ser, Ile-352→Val) Ampr | This study |
| pR52V/W116Rb | melΔ(A)B+(Arg-52→Val, Trp-116→Arg) Ampr | This study |
| pR52V/T338R | melΔ(A)B+(Arg-52→Val, Thr-338→Arg) Ampr | This study |
| pR52Q/D55Nb | melΔ(A)B+(Arg-52→Gln, Asp-55→Asn) Ampr | This study |
a
pR52K (Arg-52→Lys) is a first-site revertant isolated from the pR52Q (Arg-52→Gln) site-directed mutant.
b
The pR52V/W116R and pR52Q/D55N strains show second-site revertant substitutions that were also obtained from the K52S parental strain. These two revertants were not studied in detail.