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. 2006 Mar;188(6):2081–2095. doi: 10.1128/JB.188.6.2081-2095.2006

TABLE 3.

Effects of Fis mutations on DNA binding

Fis protein fis P II Kd (nM)a hin distal Kd (nM)a λ attR Kd (nM)a
WT 1.0 ± 0.1 1.0 ± 0.2 4.1 ± 0.4
N73A 47 ± 8 65 ± 7 91 ± 39
Q74A 1.7 ± 2 3.8 ± 0.5 6 ± 1.1
T75A 8 ± 1 6.3 ± 0.7 29 ± 13
R76A 10 ± 1 6 ± 0.9 37 ± 10b
N84A 1.5 ± 0.2 1.9 ± 2.1 157 ± 15
R85Ac >2,200d >2,200d >2,200d
T87A 1,100 ± 316 >2,200d 1,300 ± 545
R89A 232 ± 59 >2,200d 466 ± 271
K90Ac >2,200d >2,200d >2,200d
K91A 24 ± 18 >2,200d >2,200d
K93A 20 ± 2 9 ± 4 46 ± 15
K94A 37 ± 8 6.4 ± 1.4 18 ± 11
N98A 1.0 ± 0.1 1.2 ± 0.6 2.7 ± 0.7
a

Gel mobility shift assays were performed as described in the legend to Fig. 1 with 42-bp DNA fragments carrying the fis P II, hin distal, or λ attR sequences. The percentage of bound DNA at equilibrium was plotted against the Fis concentration used, as shown in Fig. 1A, and the concentrations required to achieve 50% binding were considered approximate Kd values for the binding reactions. The data are averages ± standard deviations for three experiments unless indicated otherwise.

b

The data are the average ± standard deviation for two experiments.

c

No discrete bound complexes were observed with this mutant.

d

The maximum Fis concentration used in the assays was 2.2 μM, at which less than 50% binding was observed.