Table 1.

Amino acid substitutions in the surface loops of OmpA.

				OmpA variants
Loop number	Residuea number	E. coli amino acid	S. flexneri amino acid	No change in resistance	Moderate effect	Severe effect
1	25	N	P	—	A, R	Eb
2	66	S	D	A, K	—	—
	67	V	N	—	—	A, E, H, R
	68	E	I	—	—	A, D, K, Q
3	108	S	A	—	E	R
	111	Y	P	—	A, E, R	—
	“insertion” (113, 114, 115, 116)	—	GASF	—	ΔGASF	—
4	155	H	N	R	A	E

The amino acids differing between E. coli and S. flexneri OmpA flexible loops are organized by loop and residue number. The OmpA variants shown in Fig. 3 are summarized here by their loss of function to serve as a receptor to Sf6 based on their relative titer.

^aResidue numbering based on S. flexneri OmpA.

^bVariant did not grow on MacConkey agar.