FIG. 1.

Phenotypes of Red-deficient mutants and locations of the insertions. (A) Locations of the mutations in the Red biosynthetic gene cluster. The black arrows indicate genes that are required for Red biosynthesis, while the open arrows indicate genes that are not essential. The gray arrows indicate the redD and redZ regulatory genes. The bent open arrows indicate mutations that influence only Red production, while the filled bent arrows indicate mutations that affect both Red production and Act production. The directions of the bent arrows indicate the transcript orientation of P_ermE in Tn315 in the mutants. (B) Red biosynthetic pathway. RedU is required for activation of the acyl carrier protein domains of RedO. The function of RedY is unknown (34). (C) Mutants and wild-type strain M145 were grown on YBP agar at 30°C for 2 days and 5 days. The bottoms of the plates are shown. WT, wild type. (D) Antibiotic production assay. Act production and Red production by the mutants and wild-type strain M145 were assayed in cultures grown in YBP liquid medium at 30°C for 88 h. The bars indicate the averages of three independent determinations, and the error bars indicate the standard errors. OD₅₃₀, optical density at 530 nm; OD640, optical density at 640 nm.