Table 2

Growth rate recovery of site-directed mutants

Strain

Mutations

Growth rate (± SD)

Known mutations present

Recovery

Wild type

0.23 ± 0.02

-

-

LactA

crp

0.29 ± 0.02

1/3

26%

Endpoint

0.47 ± 0.03

-

-

LactC

rph

0.27 ± 0.002

1/3

17%

cya

0.26 ± 0.03

1/3

13%

infC

0.26 ± 0.003

1/3

12%

cya + infC

0.31 ± 0.01

2/3

39%

cya + infC + rph

0.40 ± 0.02

3/3

82%

Endpoint

0.44 ± 0.01

-

-

LactD

kdtA

No growth

1/7

No growth

atoS

0.24 ± 0.01

1/7

2%

ppsA

0.23 ± 0.01

1/7

1%

relA

0.28 ± 0.01

1/7

19%

rho

0.25 ± 0.003

1/7

9%

relA + ppsA

0.33 ± 0.01

2/7

38%

kdtA + ppsA

0.27 ± 0.02

2/7

15%

kdtA + ppsA + atoS

0.28 ± 0.01

3/7

21%

kdtA + ppsA + atoS + rhoO

0.34 ± 0.03

4/7

42%

kdtA + ppsA + atoS + rho + relA

0.39 ± 0.01

5/7

64%

Endpoint

0.48 ± 0.05

-

-

LactE

yjbM

0.23 ± 0.02

1/7

1%

ppsA

0.25 ± 0.02

1/7

10%

crp

0.27 ± 0.02

1/7

17%

ppsA + crp

0.28 ± 0.03

2/7

24%

ppsA + crp + yjbM

0.31 ± 0.04

3/7

37%

Endpoint

0.43 ± 0.02

-

-

To determine the causality of the observed mutations, site-directed mutagenesis was used to place mutations individually and in combination into a wild-type (MG1655) background. Average growth rate measurements of strains grown at 30°C in lactate M9 minimal media are shown. Growth rate recovery is defined as the difference in growth rate between the mutant and wild type, divided by the difference in growth rate between the respective endpoint strain and wild type. The kdtA single mutant was unable to grow without amino acid supplementation.

Conrad et al. Genome Biology 2009 10:R118   doi:10.1186/gb-2009-10-10-r118