Generation of a non-sporulating strain of Streptomyces coelicolor A3(2) bythe manipulation of a developmentally controlled ftsZ promoter

The differentiation of Streptomyces aerial hyphae into chains of unigenomic spores occurs through the synchronous formation of multiple FtsZ rings, le ading to sporulation septa. We show here that developmental control of ftsZ transcription is required for sporulation in Streptomyces coelicolor A3(2) . Three putative ftsZ promoters were detected in the ftsQ-ftsZ intergenic r egion. In addition, some readthrough from upstream promoter(s) contributed to ftsZ transcription. S1 nuclease protection assays and transcriptional fu sions of the ftsZ promoter region to the egfp gene (for green fluorescent p rotein) provided evidence that ftsZ2p is a developmentally controlled promo ter that is specifically upregulated in sporulating aerial hyphae. This upr egulation required all the six early regulatory sporulation genes that were tested: whiA, B, G, H, I and J. The DNA sequence of the promoter indicated that it is not part of the developmental regulon that is controlled by the RNA polymerase sigma factor sigma (WhiG). A strain in which the ftsZ2p pro moter was inactivated grew normally during vegetative growth and formed aer ial mycelium, but was deficient in sporulation septation. Thus, ftsZ2p was dispensable for vegetative growth, but was required for the strain to make sufficient FtsZ to support developmentally controlled multiple cell divisio ns in aerial hyphae.