Vitális S

Characterization of the gene for factor C, an extracellular signal protein involved 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 sequence was confirmed by HPLC/electrospray ionization-mass spectrometry analysis. The full-length protein consists of 324 amino acids and has a predicted molecular mass of 34,523 Da. The mature extracellular 286 amino acid protein (31,038 Da) is probably produced by cleaving off a 38 amino acid secretion signal sequence. Southern hybridization detected facC in several other Streptomyces strains, but database searches failed to identify a protein 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.

Mode of action of Factor C, a substance of regulatory function in cyto-differentiation.

Abstract Streptomyces griseus was employed as a model for studying differentiation. Two strains were isolated; S. griseus No. 45 which produced conidia in submerged culture and strain No. 52-1 which had only filamentous mycelia. From the fermentation liquid of strain 45 a substance(s) was isolated which, if added to the culture medium of strain 52-1, also caused the latter to produce conidia. The substance was called Factor C. Its bulk constituent consists of polypeptide. By studying the mode of action of Factor C it was established that Factor C increased [14C]uracil incorporation into S. griseus mycelia. Factor C suspended the inhibitory action of actinomycin D if followed by [14C]uracil or [14C]leucine incorporation. Very similar effects were shown with Escherichia coli and Bacillus subtilis. Factor C elevated the Tm point of DNA from different sources. It is supposed that Factor C regulates cyto-differentiation by influencing messenger RNA synthesis.

Sporulation without aerial mycelium formation on agar medium by Streptomyces bikiniensis HH1, an A-factor-deficient mutant

Streptomyces bikiniensis HH1, an A-factor-deficient mutant that did not form aerial mycelium on agar medium unless supplemented with A-factor, produced spores abundantly within colonies. The spores formed on reproductive branches morphologically similar to aerial hyphae except that they did not emerge from the surface of the colonies. The spores were morphologically more heterogeneous than those formed when A-factor was added.