Table 1.

E. coli Strains and Plasmids Used in This Study

	relevant genotype and characteristics	ref or source
Strains
BL21	E. coli B F− ompT hsdSB(rB− mB−) gal dcm lon	Novagen
BL21KA	BL21 ΔacrAB	6
BL21KM	BL21 ΔmdtABC	6
BL21KAMR	BL21 ΔacrAB ΔmdtABC Δ(srl-recA)306::Tn10(Tcr)b	6
Plasmids
pSPORT1	pMB1 ori, medium-copy number cloning vector; lac-inducible expression; Apr	Gibco-BRL
pSPORT1a	pSPORT1 derivative deficient in the AatII restriction site	a
pHSG576	pSC101 ori, low-copy number vector; lac-inducible expression; Cmr	21
pHSGS	pHSG576 containing pSPORT1-derived MCS sequence under lac promoter; Cmr	6
pSMA-B10	pSPORT1 derivative harboring mdtA and mdtB with a His10 tag sequence at the 3′-end	6
pSMA-C10	pSPORT1 derivative harboring mdtA and mdtC with an upstream engineered mdtB SD sequence and a His10 tag sequence at the 3′-end	6
pSABCHisfram	pSPORT1 derivative harboring mdtABC with a His10 tag sequence at the 3′-end of mdtC	6
pSMSacIC-  linkerHindIII	pSPORT1 derivative harboring the SacI-HindIII fragment of the second MdtC subunit and linker sequence	6
pSMHindIIIB10SphI	pSPORT1 derivative harboring the HindIII-SphI fragment containing third MdtB subunit with a His10 tag	6
pSMA-BC10	pSPORT1 derivative harboring mdtA and an artificial gene for a linked Mdt B–C dimer with a C-terminal His10 tag	6
pSMA-BCB10	pSPORT1 derivative harboring mdtA and an artificial gene for a linked Mdt B–C–B trimer with a C-terminal His10 tag	6
pSMA-BCLCCLBCL10	pSPORT1 derivative harboring mdtA and an artificial gene for a cysteineless linked Mdt B–C–B trimer with a C-terminal His10 tag	a

^aThis study.

^bAbbreviations: Ap^r, ampicillin resistant; Cm^r, chloramphenicol resistant; Tc^r, tetracycline resistant.