Table S3.

β-Galactosidase assays of mepS::lacZ fusions

Strains/genotypes	β-galactosidase values, Miller units*
MC4100 ϕ(mepS’::lacZY-Kan) (A600∼0.6)†	763 ± 53
MC4100 ϕ(mepS’::lacZY-Kan) (A600∼1.2)	950 ± 64
MC4100 ϕ(mepS’::lacZY-Kan)/pTRC99a-mepS	820 ± 75
MC4100 ϕ(mepS’::lacZY-Kan)/pTRC99a-mepS (with 100 μM IPTG)	910 ± 103
MC4100 ϕ(mepS’::lacZY-Kan) ΔnlpI::frt	760 ± 32
MC4100 ϕ(mepS’::lacZY-Kan) Δprc::frt	863 ± 27

^*Mean values with SD are shown. Values are taken from three independent experiments. Assays are done as described in Miller (39).

^†The lacZ fusion strains were made as described (43). Because these strains lack the mepS structural gene, a plasmid-borne copy of mepS (pMN80; pTRC99a-mepS; 9) was used for complementation, and no difference in the activity was observed in the presence or absence of mepS.