Ribonucleic Acid and Protein Synthesis During Germination of Myxococcus xanthus Myxospores

Abstract

Ribonucleic acid (RNA) and protein synthesis during myxospore germination were examined. When RNA synthesis was inhibited more than 90% by either actinomycin D (Act D) or rifampin, germination was prevented. The data were consistent with the interpretation that rifampin did not interfere with protein synthesis in any way other than by inhibition of messenger RNA formation. Act D concentrations as high as 20 ug/ml did not totally inhibit RNA synthesis. In the presence of 8 ,ug of Act D/ml, germinating myxospores synthesized transfer RNA, 16S RNA, and 23S RNA. Evidence was presented which indicated that messenger RNA was also synthesized early in the germination period both in the presence and absence of 8 ,g of Act D/ml. One explanation for the escape synthesis of RNA in germinating myxospores is that Act D exerts a differential effect on the transcription of larger versus smaller cistrons, the latter having a lower probability of binding Act D. We have found that in the presence of 8 Mg of Act D/ml, escape RNA synthesis in myxospores was 25% for 23S RNA, 55% for 16S RNA, and more than 90% for 4S RNA. We have shown that germination of myxospores requires both RNA and protein synthesis during the first 25 to 35 min in germination medium. This finding does not support the earlier suggestion by Ramsey and Dworkin that a stable germination messenger RNA is required for germination of the myxospores of Myxococcus xanthus. ' Present address:

Recent advances in the social and developmental biology of the myxobacteria.

“…In a similar fashion, swarming Proteus strains often fail to merge with each other and form lines of demarcation referred to as the Dienes phenomenon (36). Similar to the situation with the establishment of myxobacterial territoriality, the Dienes phenomenon has been shown to be due to the elaboration of protocines, 96 DWORKIN MICROBIOL. REV.…”

“…Germination of M. xanthus myxospores was first described by Thaxter (247). A series of morphological (51) and physiological studies were done on the germination of glycerol-induced myxospores (96,185,186), but this approach was abandoned when it became clear that there were important physiological differences between glycerol-induced and fruiting body myxospores (100). Since then, there have been two publications on the germination of fruiting body myxospores.…”

Induction of germination in Myxococcus xanthus fruiting body spores

“…Dworkin & Gibson (1964) described a method for inducing rapid and synchronous conversion of vegetative cells into myxospores, without the intervening formation of fruiting bodies, by incubation in liquid medium containing glycerol. Previous reports on the physiology and early molecular analysis of myxospore germination are mostly related to germination of these glycerol-induced spores (Ramsey & Dworkin, 1968,1970; Juengst & Dworkin, 1973). The sporelike cells that result from glycerol induction differ in several structural and physiological aspects from fruiting body spores (Bacon & Eiserling, 1968; Bacon et al ., 1975; Inouye et al ., 1979).…”

Intracellular and Extracellular Nucleotides and Related Compounds During the Development of Myxococcus xanthus

“…during harvesting, washing, freezing, and thawing of the 6-h myxospores. Limited data on the uptake of acetate by myxospores and vegetative cells (31), extractability of small molecules from myxospores by trichloroacetic acid, uptake of uridine by myxospores (14), and uptake of amino acids by myxospores (M. Dworkin, unpublished data) suggests that the myxospores are permeable to small molecules. Thus, leakage seems a very real possibility.…”

“…About 2 h later (Klett 130) the culture was induced with glycerol, and myxospore samples were harvested at 4 h postinduction. Fortymilliliter samples of the 4-h myxospores were harvested by centrifugation at 4 C. A 1-ml portion of the extracted material was added to 15 ml of Bray scintillation fluid (14) and counted in a Packard Tri-Carb model 3375 liquid scintillation counter.…”