Table 1.

Effect of mutations on virus infectivity, pore-associated conformational rearrangement, and mechanical stiffness at S5 regions in the MVM capsid

Mutant *	Titer *‡	Tm (°C) †‡	ks (N/m)§	Fz ¶	n ¶	T ∥
WT	1	46.1 ± 0.8	0.59 ± 0.11	99	6	-
V40A	1 × 10-4	No	0.81 ± 0.23	80	7	6 × 10-12
S43A	< 4 × 10-5	No	0.83 ± 0.23	66	6	1 × 10-11
N149A	< 8 × 10-7	No	0.93 ± 0.24	58	6	2 × 10-15
N170A	< 5 × 10-6	No	0.98 ± 0.21	123	5	3 × 10-42
L172A	No	No	0.79 ± 0.27	74	7	6 × 10-08
D263A	< 8 × 10-6	No	0.87 ± 0.27	138	6	2 × 10-21
D58A	0.14	44.2 ± 0.2	0.57 ± 0.05	44	5	0.76
N74A	0.93	48.5 ± 1.0	0.57 ± 0.15	62	7	0.34
L113A	2.17	44.6 ± 0.3	0.60 ± 0.15	59	5	0.66
L113F	0.88	43.3 ± 0.5	0.57 ± 0.17	66	5	0.30
L143F	0.99	49.5 ± 0.9	0.62 ± 0.13	59	6	0.14
I167A	0.07	45.2 ± 1.0	0.53 ± 0.15	49	7	0.01
N183A	0.07	45.1 ± 0.2	0.57 ± 0.07	44	5	0.95
Y188F	1.07	48.2 ± 0.5	0.63 ± 0.10	72	5	0.04
Y188W	0.56	48.8 ± 2.2	0.60 ± 0.18	49	6	0.64
M497L	1.05	48.9 ± 1.2	0.59 ± 0.11	61	5	0.78

^*Mutants are grouped in two series. The first (V40A to D263A) includes those whose virions had drastically reduced infectivity; the second (D58A to M497L), those whose virions had an infectivity comparable to WT. Mutants are listed in numerical order in each series. Titer indicates normalized virus infection titer at 37 °C, relative to WT. Mutation L172A was lethal (37).

^†Transition temperature (average ± standard deviation) for the fluorescence-detected conformational transition of the capsid. No: no transition occurred.

^‡Titers (except for L113A, L113F, L143F, Y188F, Y188W, M497L) and T_m (except for D58A, N183A) had been previously obtained (36, 45) and are shown to facilitate comparison with the results of mechanical analysis.

^§Spring constant k_s (average ± standard deviation).

^¶Number of events (Fz) and individual viral particles (n) analyzed.

^∥Value of T in a Student t-test (see text).