TABLE 7.

Substitutions and activities of 157⁴⁸G and 135³⁰D mutant FIV PRs

Protease	Position and amino acid																									Activitya
																										FIV FS	HIV FS	VI
FIV	35	37	53	54	55	56	57	59	62	63	64	65	66	67	88	90	97	98	99	100	101	105	106	107	108
	I	I	R	Q	N	M	I	V	G	K	R	G	T	N	N	C	L	I	Q	P	L	D	N	M	I
HIV	D	V	P	K	M	I	G	I	F	I	K	V	R	Q	T	L	T	P	V	N	I	N	L	L	T
	30	32	44	45	46	47	48	50	53	54	55	56	57	58	74	76	80	81	82	83	84	88	89	90	91
Mutants
F9s		V			M	I		I								T	P	V	N	I						ND	ND
F12s		V			M	I	G	I	F	I							T	P	V	N	I					+++	+
F12s′	D	V		K	M	I	G	I									T	P	V	N	I					ND	ND
F13s	D	V			M	I	G	I	F	I							T	P	V	N	I					ND	ND
F14s	D	V		K	M	I	G	I	F	I							T	P	V	N	I					ND	ND
F15s	D	V	P	K	M	I	G	I	F	I							T	P	V	N	I					ND	ND
F15s′	D	V		K	M	I	G	I	F	I						L	T	P	V	N	I					ND	ND
F16s	D	V		K	M	I	G	I	F	I						L	T	P	V	N	I	N				ND	±
F17s	D	V		K	M	I	G	I	F	I					T	L	T	P	V	N	I	N				±	+	+
F20s	D	V		K	M	I	G	I	F	I	K	V	R	Q		L	T	P	V	N	I	N				ND	±
F21s	D	V		K	M	I	G	I	F	I	K	V	R	Q	T	L	T	P	V	N						ND	+	+
F23s	D	V		K	M	I	G	I	F	I	K	V	R	Q		L	T	P	V	N	I	N	L	L	T	ND	ND
F24s	D	V		K	M	I	G	I	F	I	K	V	R	Q	T	L	T	P	V	N	I	N	L	L	T	ND	±

^aActivity of mutants was assayed on both FIV and HIV-1 fluorogenic substrates (FS), which represent FIV CA/NC2 and HIV-1 P2/NC cleavage junctions. VI, fluorogenic substrate representing the HIV-1 CA/P2 cleavage junction. ND, activity not detectable after monitoring cleavage for 6 min; ±, marginal activity; +, <5% of wild-type activity; +++, >50% of wild-type activity.