Transcriptional and functional analysis of the gene for factor C, an extracellular signal protein involved in cytodifferentiation of Streptomyces griseus

Factor C is an extracellular signal protein involved in cellular differenti ation in Streptomyces griseus. Nuclease S1 mapping experiments revealed tha t transcription of the gene takes place from a single promoter in a develop mental-stage specific manner. The latter was also confirmed by in vivo prom oter probing. The sequence of its promoter suggests that the gene is not tr anscribed by the major sigma factor. The cloned gene expressed from its own promoter in low- and high-copy-number vectors restored normal sporulation to a bald mutant of Streptomyces griseus. Computer analysis of the amino ac id sequence revealed the presence of a transmembrane localization segment w ith the N-terminus positioned inside the cell. These data fit well into our working model that points at an important role for factor C in the morphog enesis of Streptomyces griseus.