Table 2 LpxB-specific activities

From: Crystal structure of lipid A disaccharide synthase LpxB from Escherichia coli

LpxB

Specific activity ± SE (μmol min−1 μmol−1)

95% Confidence interval

Percent of wild type

Wild-type

6.17 ± 5.3*10−1

4.99 to 7.34

100

L72SL75S

1.08*10−1 ± 2.3*10−2

5.62*10−2 to 1.59*10−1

1.74

L72SL76 S

1.99 ± 3.3*10−1

1.21 to 2.76

32.2

L75SL76S

1.89 ± 2.3*10−1

1.35 to 2.42

30.6

V66SV68SL69S (VVL)

3.26*10−3 ± 5.5*10−4

2.02*10−3 to 4.49*10−3

5.28*10−2

L72SL75SL76S (LLL)

6.34*10−5 ± 1.04*10−5

4.03*10−5 to 8.66*10−5

1.03*10−3

6S

Below detection limit

ND

ND

N316A (NA)

2.11*10−2 ± 1.5*10−3

1.78*10−2 to 2.45*10−2

3.42*10−1

F298AN316A (FN)

4.80*10−4 ± 6.2*10−5

3.33*10−4 to 6.28*10−4

7.79*10−3

R201A (RA)

3.16*10−4 ± 2.3*10−5

2.66*10−4 to 3.66*10−4

5.12*10−3

FN + RA (50% FN)

1.06*10−2 ± 9*10−4

8.50*10−3 to 1.27*10−2

1.72*10−1

FN + RA (37% FN)

3.63*10−3 ± 3.7*10−4

2.76*10−3 to 4.50*10−3

5.89*10−2

FN + RA (24% FN)

2.91*10−3 ± 1.6*10−4

2.55*10−3 to 3.27*10−3

4.71*10−2

FN + RA (15% FN)

2.35*10−3 ± 2.6*10−4

1.74*10−3 to 2.95*10−3

3.81*10−2

FN + RA (7.3% FN)

1.03*10−3 ± 1.5*10−4

6.70*10−4 to 1.38*10−3

1.66*10−2

NA + RA1:1

1.06*10−2 ± 1.3*10−3

7.56*10−3 to 1.35*10−2

1.71*10−1

Wild-type (NDSB-201)

3.42 ± 6.0*10−1

1.994 to 4.84

55.4

6S (NDSB-201)

Below detection limit

ND

ND

  1. Reactions were performed in triplicate with 1 nM to 10 μM LpxB (as appropriate per variant), 31 μM UDP-DAG, ~ 0.13 mM lipid X, 1 mg ml−1 BSA, 0.1 M Tris-HCl pH 8.0, and 0.1% Triton X-100 at ambient temperature (21 °C). Reactions were quenched and UDP was quantified using a UDP-Glo Glycosyltransferase Assay kit (Promega), which quantifies free UDP by a luciferase coupled reaction. Specific activities with standard errors and 95% confidence intervals were calculated by linear regression of UDP concentrations at three or four time points for each LpxB variant in Graphpad Prism v7.03
  2. ND, insufficient data