The SARS Coronavirus S Glycoprotein Receptor Binding Domain: Fine Mapping and Functional Characterization

Table 1 S RBD mutants, expression levels and binding to ACE2.

Mutant	Mutation	Expression	Binding	ASA
1	E327	98	83	123
2	K333	86	90	176
3*	K344	95	102	159
4	K390	104	1	44
5	D392	110	95	69
6	D393	30	100	10
7	K411	90	103	33
8	D414	120	130	113
9	D415	90	102	97
10*	R426	73	7	95
11	N427	100	111	121
12	D429	103	0	9
13	T431	131	64	59
14	K439	85	87	65
15	R441	10	15	3
16*	Y442	105	110	68
17*	R444	80	86	52
18	H445	124	103	113
19	K447	87	85	138
20	R449	96	101	178
21	F451	69	71	64
22	D454	50	4	25
23	I455	77	6	89
24	D463	87	81	70
25*	L472	95	99	172
26	N473	100	0	70
27	W476	80	76	126
28	F483	91	3	2
29	Q492	95	3	5
30	Y494	50	7	21
31	R495	97	19	7
32	E502	110	84	175
33	S17–276	90	0
34	S319–518	100	100

The mutants that significantly decrease binding to ACE2 are shown in bold. The * denotes mutant residues that are naturally occurring in various SCV strains (see Fig. 6A). The binding and expression values for the individual mutants are expressed as a percentage of the value for the S319–518 (wt) that is assumed 100%. The values of accessible surface area (ASA, Å²) for mutant residues were calculated from the crystal structure of the S RBD-ACE2 complex (coordinates provided by S. Harrison) by using the Lee and Richards' algorithm [23] with a probe radius of 1.4 Å.