DEVELOPMENTAL BIOLOGY OF STREPTOMYCES

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Streptomyces are the primary source of medically importnt antibiotics. This research project is designed at understanding the molecular and physiological processes involved in sporulation and spore germination of Streptomyces viridochromogenes and S. griseus. Germinating spores excrete and degrade intracellular reserves of trehalose and a glutamic acid-rich protein. Experiments are designed to determine the nature of the reserves and how the enzymes degrading them are activated during initiation of germination. Trehalose comprises 25-30% of the dry weight of spores. The idea that trehalose is involved in desiccation resistance and dormancy of spores is being studied. Non-sporulating streptomycin non-producing mutants of S. griseus acquire both properties when supplied a butyrolactone compound, A-factor, produced by the parent organisms. A-factor induces formation of NAD-glycohydrolase in the mutants. We will test the hypothesis that the glycohydrolase modifies sporulation-specific proteins by an ADP-ribosylatin reaction. ADP-ribosylation of proteins is a major mechanism of post-translational modificaton in eucaryotes. This work would be the fist report of this reaction as part of the normal growth and development of bacteria. There is a possibility that the modification involves expression of antibiotic synthesis as well as sporulation. We intend to study the glycohydrolase, clone the gene for its production in order to study its control, and to identify the proteins modified by the ADP-ribosylation reaction.