FIG. 6.

Growth of mycobacterial strains in low iron and stability of mutated IrtAs. (A) M. tuberculosis strains were grown in LIMM. Growth was monitored each day by measuring the OD₅₄₀. H37Rv (⧫), ST73 (□), and ST73 complemented with wild-type irtAB (▵), irtAR70A-irtB (▪), irtAY72A-irtB (▴), and irtAT73A-irtB (•) were examined. The results of one representative experiment are shown. The experiment was performed three times. (B) Stability of noncomplementing mutated IrtAs. S-tagged IrtA wild type (lane 1), S-IrtAY72A (lane3) and S-IrtAT73A (lane 4) were expressed in M. smegmatis under acetamide induction. M. smegmatis harboring the acetamide-inducible empty vector was used as a negative control (lane 2). Membrane fractions were isolated, the protein concentration was determined, and an equivalent amount of protein from each extract was loaded on a SDS-7.5% PAGE gel. S-IrtAs were detected by Western analysis with an anti-S monoclonal antibody.