Table 1. Bacterial stains used in this study.

Strain	Relevant genotype/descriptiona	Comments	Reference
JRS4	wild type/wt		Scott et al (1986)
SLO6	sloΔ113−447/SLO−	SLO-deficient mutant	Ruiz et al (1998)
SPN1	spnΔ177−319/SPN−	SPN-deficient mutant	Madden et al (2001)
NGM1	sloY255A/prepore-locked	Expresses prepore-locked SLO	This study
NGM2	sloG398V/G399V/monomer-locked	Expresses monomer-locked SLO	This study
SLOΔ37−102	sloΔ37−102/SLOΔNT	Expresses SLO lacking an amino-terminal translocation domain	Meehl & Caparon (2004)
NGM3	sloΔ37−102,Y255A/preporeΔNT	Expresses prepore-locked SLO lacking an amino-terminal translocation domain	This study
SLO, streptolysin O; SPN, Streptococcus pyogenes nicotinamide adenine dinucleotide-glycohydrolase; NT, amino terminus; wt, wild type.
aAllelic replacement was used to substitute the endogenous allele in wild-type JRS4 with the mutant alleles.