Characterization of the gene for factor C, an extracellular signal proteininvolved in morphological differentiation of Streptomyces griseus

The gene encoding factor C (facC), an extracellular signal protein involved in cellular differentiation, was cloned from Streptomyces griseus 45H, and the complete nucleotide sequence was determined. The deduced amino acid se quence was confirmed by HPLC/electrospray ionization-mass spectrometry anal ysis. The full-length protein consists of 324 amino acids and has a predict ed molecular mass of 34 523 Da. The mature extracellular 286 amino acid pro tein (31038 Da) is probably produced by cleaving off a 38 amino acid secret ion signal sequence. Southern hybridization detected facC in several other Streptomyces strains, but database searches failed to identify a protein De partment of with significant homology to factor C. Expression of facC from a low-copy-number vector in S. griseus 52-1 resulted in a phenotypic effect similar to that given by exogenously added factor C protein.