TABLE 1.

Bacterial strains and plasmids used in this study

Strain or plasmid	Relevant genotype or description	Reference or source
Strains
E. coli
HB101	pro leu thi lacY hsdR endA recA rpsL20 ara-14 galK2 xyl-5 mtl-1 supE44	4
DH5α	F−endA1 hsdR17 (rK− mK+) supE44 thi-1 recA1 gyrA96 (Nalr) relA1 Δ(lacIZYA-argF)U169 deoR[φ80dlacΔ(lacZ)M15]	GIBCO-BRL
Y. pestis medievalis biotypea
KIM5-3001	Smr; Pgm−; pCD1 (Lcr+), pPCP1 (Pla+), pMT1	27
KIM8-3002	Smr; Pgm−; pCD1 (Lcr+), pPCP1− (Pla−), pMT1	33
KIM6+	Pgm+; pCD1− (Lcr−), pPCP1 (Pla+), pMT1	R. R. Brubaker
KIM6	Pgm−; pCD1− (Lcr−), pPCP1 (Pla+), pMT1; two versions used in this study were made by screening Y. pestis KIM5 (Pgm−; pCD1 [Lcr+], pPCP1 [Pla+], pMT1) for spontaneous loss of pCD1 and by screening Y. pestis KIM6+ for spontaneous Hms− colonies (having deleted the pgm locus [15])	R. R. Brubaker
KIM10	Pgm−; pCD1− (Lcr−), pPCP1− (Pla−), pMT1	R. R. Brubaker
KIM5-3001.1	Pgm−; psaA3:mTn3Cm (Psa−), pCD1 (Lcr+), pPCP1 (Pla+), pMT1	27
KIM6-2008	Kmr; hmsH-2008::mini-kan (Hms−); pCD1− (Lcr−), pPCP1, pMT1	34
Orientalis biotype EV76b	Pgm−; pYV76 (Lcr+), pPCP2 (Pla+), pMT2	R. R. Brubaker
Y. enterocoliticac
WA	O:8; pYVWA (Lcr+)	7
WA-LOX	O:8; pYVWA− (Lcr−)	35
Plasmid pTrc99A	Expression vector; Apr; ColE1 replicon; Ptrc promoter upstream of multiple cloning sequence	Pharmacia

^aNative plasmids of Y. pestis KIM are the 70-kb pCD1 encoding the Ysc type III secretion-targeting apparatus and LcrV and Yops (Lcr⁺ phenotype) (38), the 9.6-kb pPCP1 encoding the surface protease Pla and the bacteriocin pesticin and its immunity protein (44, 50), and the 100-kb pMT1 encoding the capsular Caf1 protein and the “murine toxin” Ymt (28). 

^bNative plasmids in Y. pestis EV76 confer the same phenotypes as in Y. pestis KIM (14, 43). 

^cThe single virulence plasmid in Y. enterocolitica WA confers the Lcr⁺ phenotype (35).