FIG. 9.
Effect of an invB deletion on transcription of sopEM45 and sopE2M45. Transcription of sopEM45 and sopE2M45 was measured by using transcriptional lacZ reporter constructs (Table 1). SL1344 (wild type) and the secretion-deficient strains SB161 (ΔinvG) and M590 (ΔinvG invB::aphT) harboring the sopEM45 (pM185) and sopE2M45 (pM687) expression vectors, respectively, were grown under SPI-1-inducing conditions. One-hundred-microliter samples were removed and assayed for β-galactosidase activity. Values are β-galactosidase units; standard deviations were determined from the results of three independent experiments.