Table II. Residues involved in the MalT interaction patch as deduced by mutational screening of repressor-negative MalY mutants.
Plasmid | β-galactosidase activitya |
|
---|---|---|
before inductionb | after inductionc | |
Wild-type | 0.03 | 0.005 |
Null (vector) | 2.17 | 2.68 |
T83A | 1.29 | 0.03 |
T83Id | 1.16 | 0.47 |
A84T | 0.29 | unstable |
A84V | 1.11 | 0.01 |
C181Rd | 0.99 | 0.01 |
C181T | 1.43 | 0.02 |
C181T, T244Y | 0.26 | unstable |
E185G | 1.16 | 0.02 |
A188T | 0.92 | 0.002 |
D189G | 0.58 | 0.001 |
I215Td | 1.46 | 1.26 |
S218R | 1.43 | 0.22 |
N219D | 1.26 | 0.01 |
A221Vd | 1.45 | 0.33 |
aSpecific β-galactosidase activity of the malK–lacZ fusion of strain EZ7 after growth overnight in minimal medium with glycerol as the carbon source. Specific activity is given in μmol substrate hydrolysed/min/mg protein.
bThe reduction of MalY-related repressor function is proportional to the value of β-galactosidase activity before induction with IPTG.
cInduction was with 100 μM IPTG.
dMutation that was obtained more than once.