Table 3.

Phenotypic effects of mepA mutations found in clinical strains and those produced in conserved negatively charged residues replicated in pK436 and expressed in SA-K2124

Parameter	Value in strain (mutation)a/location of substitutionb:
	Clinical origin			Conserved negatively charged residues
	K4916 (A302S)/loop 8–9c	K4920 (A392V)/TMS 11	K4950 (A397V)/TMS 11	K5084 (D48A)/loop 1–2	K5260 (D48E)	K5262 (D48N)	K5086 (E156A)/TMS 4c	K5264 (E156D)	K5266 (E156Q)	K5088 (D183A)/TMS 5	K5268 (D183E)	K5270 (D183N)	K5090 (E423A)/TMS 12	K5272 (E423D)	K5274 (E423Q)
Relative susceptibility
BAC	4 (0.25)	2 (2)	2 (1)	1	1	1	1	1	1	1	1	1	1	1	2
CHX	0.5 (0.5)	0.5 (0.5)	0.5 (0.5)	0.5	0.5	1	1	0.25	0.25	0.5	0.5	0.5	1	0.25	1
DQ	1 (0.5)	1 (4)	1 (1)	0.5	0.5	1	0.5	1	0.25	1	2	1	1	1	2
EtBr	2 (1)	2 (2)	1 (0.5)	1 (1)	1 (0.5)	1 (0.5)	1 (0.5)	0.5 (0.5)	0.5 (0.5)	1 (0.5)	0.5 (1)	0.5 (1)	1 (0.5)	1 (0.5)	2 (0.5)
Hoechst 33342	2 (1)	2 (4)	1 (2)	1	0.5	0.5	1	0.5	0.25	1	0.5	0.25	0.5	0.25	0.5
Norfloxacin	1 (1)	0.5 (1)	0.5 (1)	1	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	1	0.5
Pentd	2 (1)	2 (8)	4 (8)	2	2	1	0.5	0.5	0.5	0.5	0.5	0.5	1	1	2
TPP	1 (0.5)	1 (1)	1 (0.5)	1	0.5	0.5	1	0.5	0.25	0.5	0.5	0.25	0.5	1	1
EtBr efflux (%) ± SD	52.6 ± 14.9	60.1 ± 6.0	62.6 ± 2.9	48.9 ± 3.0	41.4 ± 3.5	28.2 ± 7.0	5.4 ± 0.8	12.5 ± 5.0	6.5 ± 3.2	9.3 ± 2.4	12.9 ± 3.4	8.0 ± 1.8	18.0 ± 2.0	42.1 ± 7.1	65.1 ± 6.2
% Changee	93	121	130	80	52	4	−80	−54	−76	−66	−53	−71	−34	55	139
P value	<0.001	<0.001	<0.001	<0.001	<0.001	NS	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
IC50 of EtBr efflux (reserpine/paroxetine)	0.6/0.5	0.4/0.7	0.6/1.2	1.6/ND	0.6/ND	0.4/ND	ND/ND	ND/ND	ND/ND	ND/ND	ND/ND	ND/ND	1/ND	0.8/ND	1/ND

^aSusceptibility, fold reduction in MIC in the presence of 20 μg/ml reserpine (in parentheses), and IC₅₀ data were normalized to K3486, in which wild-type mepA is expressed. ND, not done.

^bPredicted by SOSUI.

^cAlternate location predicted by the TMHMM algorithm. See the text for details.

^dPent, pentamidine.

^eCompared to K3486.