RNA and ribosomal protein patterns during aerial spore germination in Streptomyces granaticolor

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Abstract
Disruption of the external sheath of Streptomyces granaticolor aerial spores and subsequent cultivation in a rich medium result in a synchronous germination. This method was used to analyze RNA and protein patterns during the germination. The germination process took place through a sequence of time-ordered events. RNA and protein synthesis started during the first 5 min and net DNA synthesis at 60-70 min of germination. Within the first 10 min of germination, synthesis of RNA was not sensitive to the inhibitory effect of rifamycin. During this period rRNA and other species including 4.sbd.5-S RNA were synthesized. Dormant spores contained populations of ribosomes or ribosomal precursors that were structurally and functionally defective. The ribosomal particles bound a sporulation pigment(s) of the melanine type. The ribosomal proteins complexed to the pigments formed insoluble aggregates which were easily removed from the ribosomes by 1 wash with 1 M NH4Cl. During the first 10 min of germination, pigment(s) were liberated from the complexes with the ribosomes and protein extracts of the washed ribosomes had essentially the same pattern as the extracts of ribosomes of vegetative cells. These structural alterations were accompanied by enhancement of the ribosome activities in polypeptide synthesis in vivo and in vitro. When the spores were incubated with a 14C-labeled amino acid mixture in the presence of rifamycin, only 3 proteins (GS1, GL1 and GS9) were identified to be radiolabeled in the extracts from the washed ribosomes. Liberation of the sporulation pigment(s) from the complexes with ribosomal proteins and assembly of de novo synthesized proteins and proteins from a pre-existing pool in the spore are involved in the reactivation of the ribosomes of dormant spores of S. granaticolor.