Hypersusceptibility mechanism of Tenofovir-resistant HIV to EFdA

Retrovirology

Table 4 Steady state kinetic parameters for EFdA-TP and dATP incorporation by WT and K65R HIV-1 RTs

Enzyme	dNTP	K_m(μM)	k_cat(min^-1)	k_cat/K_m(min^-1 · μM^-1)	Selectivity^a	Fold change^b
T _d26 /P _d18-P5
WT RT	dATP	2.38 ± 0.27	1.58 ± 0.12	0.66	1	1
	EFdA-TP	0.66 ± 0.04	3.26 ± 0.42	4.94	7.5	1
K65R RT	dATP	5.99 ± 0.81	0.92 ± 0.14	0.15	1	0.8
	EFdA-TP	1.83 ± 0.34	1.74 ± 0.42	0.95	6.3	0.8
T _d31 /P _d18-P0
WT RT	dATP	0.33 ± 0.07	6.32 ± 0.14	19.15	1	1
	EFdA-TP	0.23 ± 0.01	4.73 ± 0.33	20.57	1.1	1
K65R RT	dATP	0.42 ± 0.01	3.62 ± 0.71	8.62	1	1
	EFdA-TP	0.31 ± 0.02	3.07 ± 0.15	9.90	1.1	1
T _d31A /P _d21
WT RT	dATP	0.37 ± 0.08	3.64 ± 0.57	9.84	1	1
	EFdA-TP	0.19 ± 0.06	3.54 ± 0.44	18.63	1.9	1
K65R RT	dATP	1.06 ± 0.11	3.68 ± 0.28	3.47	1	0.9
	EFdA-TP	0.53 ± 0.05	3.38 ± 0.29	6.38	1.8

Values are mean ± S.D. of two to four independent experiments and were determined from Michaelis-Menten equation using GraphPad Prism 4.
^aSelectivity is the ratio of the incorporation efficiency (k_cat/K_m) of EFdA-TP over that of dATP ([k_cat/K_m]_EFdA-TP / [k_cat/K_m]_dATP).
^bFold Change is the ratio of the selectivity in K65R over the selectivity in WT RT.

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