Directed evolution of an E. coli inner membrane transporter for improved efflux of biofuel molecules

Table 1 Rates of n- octane and α-pinene efflux from JA300A expressing AcrB variants

Hydrocarbons	AcrB variants	Hydrocarbon release rate constant/min^-1	AcrB hydrocarbon efflux rate constant^a/min^-1	Relative AcrB efflux rate
n-octane	none	0.227 ± 0.007	-	-
	Wild-type	0.312 ± 0.010	0.085	1.00
	1G1	0.352 ± 0.011	0.125	1.47
	1G2	0.349 ± 0.009	0.122	1.44
	N189H	0.318 ± 0.018	0.091	1.07
	L357Q	0.290 ± 0.011	0.063	0.74
	T678S	0.318 ± 0.025	0.091	1.07
	T678A	0.334 ± 0.015	0.107	1.26
	Q737L	0.355 ± 0.023	0.128	1.51
	M844L	0.325 ± 0.010	0.098	1.15
	M844A	0.339 ± 0.015	0.112	1.31
	M987T	0.292 ± 0.019	0.065	0.77
	V1028M	0.304 ± 0.008	0.077	0.91
α-pinene	none	0.282 ± 0.018	-	-
	Wild-type	0.297 ± 0.014	0.015	1.00
	1G1	0.342 ± 0.015	0.060	4.00
	1G2	0.328 ± 0.018	0.046	3.07
	N189H	0.322 ± 0.012	0.040	2.69
	L357Q	0.296 ± 0.009	0.014	0.96
	T678S	0.319 ± 0.008	0.037	2.44
	T678A	0.330 ± 0.012	0.048	3.20
	Q737L	0.340 ± 0.008	0.058	3.89
	M844L	0.318 ± 0.008	0.036	2.41
	M844A	0.327 ± 0.019	0.045	3.00
	M987T	0.293 ± 0.005	0.011	0.75
	V1028M	0.297 ± 0.005	0.015	0.97

^a Calculated by taking the difference between the hydrocarbon release rate constants of JA300A expressing no AcrB and JA300A expressing variants of AcrB.

ISSN: 2731-3654