Exploring the full natural diversity of single amino acid exchange reveals that 40–60% of BSLA positions improve organic solvents resistance

Bioresources and Bioprocessing

Table 3 Effect of amino acid location (buried, exposed) on organic solvent resistance of BSLA when replacing each type of amino acid in BSLA WT

	Location of amino acid positions in BSLA (%)
	Exposed positions (128; 71%)				Buried positions (53; 29%)
	+ (275)	= (1777)	− (319)	× (189)	+ (96)	= (435)	− (220)	× (309)
DMSO
Aromatic	10	15	22	15	14	12	16	19
Aliphatic	25	27	21	17	21	36	20	14
Polar	31	36	33	38	44	36	41	26
Charged	35	23	24	30	22	15	23	41
	+ (138)	= (1903)	− (330)	× (189)	+ (21)	= (385)	− (345)	× (309)
DOx
Aromatic	16	15	17	15	10	12	15	19
Aliphatic	17	27	19	17	14	39	20	14
Polar	26	35	35	38	52	40	37	26
Charged	41	23	28	30	24	9	28	41
	+ (152)	= (1883)	− (336)	× (189)	+ (29)	= (394)	− (328)	× (309)
TFE
Aromatic	19	15	15	15	17	12	15	19
Aliphatic	16	27	24	17	10	37	22	14
Polar	30	36	32	38	38	40	38	26
Charged	34	23	29	30	34	11	26	41

Sixteen patterns per organic solvent are shown. The absolute number of BSLA variants per type is shown in brackets
Amino acid groups: aromatic (F, Y, and W), aliphatic (A, V, L, I, and G), charged (D, E, H, K, and R), and polar (C, M, P, S, T, N, and Q). For activity group definitions (+, =, −, ×) see text. Values are given as percentages for easier comparison, as BSLA amino acid composition is not evenly distributed (43.6% aliphatic, 29.8% polar, 18.2% charged, 8.3% aromatic). The number of inactive variants (×) was the same for all organic solvents. Column “×” shows that the number of inactive variants resulted from amino acid substitutions. The activity was measured in a buffer plate which was used as reference (absence of organic solvent) for comparison. Therefore, the number of inactive variants was the same for all four organic solvents