The association of newly synthesized vaccinia virus DNA with proteins in infected HeLa cells was followed. A shift from a high density to a low density complex occurred between 3 and 6 h after infection. This process was not affected by isatin beta thiosemicarbazone (IBT), an inhibitor of pox virus growth. At 22 h after infection in the absence of IBT, mature virions of high density were observed; however, in the presence of the drug, high density DNA-protein complexes, which lack the two main virus core polypeptides, were formed.

DNA, Viral↗

PubMed1978

Actinomycin biosynthesis by protoplasts derived from Streptomyces parvulus.

Conditions are described for the formation of protoplasts from Streptomyces parvulus that are able to synthesize actinomycin D de novo. Antibiotic synthesis by protoplasts, in contrast to that by mycelium, was sensitive to inhibition by actinomycin D and to a decrease in sucrose concentration. On the other hand, synthesis by mycelium was much more sensitive to inhibition by amino acid analogs (d-valine, cis-3-methylproline, and alpha-methyl-dl-tryptophan). In addition, the uptake of amino acids (l-methionine, sarcosine, and l- and d-valine) by protoplasts was significantly lower than that by mycelium. The advantages and limitations of using protoplasts for studying in vivo actinomycin synthesis are discussed.

Dactinomycin↗

PubMed1978

Gene dosage effects of the structural gene for a lipoprotein of the Escherichia coli outer membrane.

The gene dosage effects of the structural gene (lpp) for the lipoprotein of the Escherichia coli outer membrane were examined. A novel F-prime factor containing the lpp gene was constructed. The amount of the free-form lipoprotein in the merodiploid strain carrying the F-prime factor was found to be about two times as great as that in the corresponding haploid strain. On the other hand, the amount of the bound-form lipoprotein, which is vovalently linked to the peptidoglycan, was not significantly different in the merodiploid strain as compared with the corresponding haploid strain. The present results suggest that the lpp gene is expressed constitutively in contrast to another major protein of the E. coli outer membrane, tolG protein (protein II, D. B. Datta et al., J. Bacteriol. 128:834-841, 1976). The F-prime factor isolated may include a portion of the E. coli chromosome (located between 33 and 36 min on the genetic map) that is not covered by any other F-prime factor.

Bacterial Proteins↗

PubMed1978

Lipoprotein from Proteus mirabilis.

The biosynthesis of a Proteus mirabilis outer membrane protein of molecular weight of approximately 7,000 was found to be relatively resistant to puromycin and rifampin, as is the case for the Escherichia coli liporotein. Furthermore, the existence of the lipoprotein in P. mirabilis was indicated by a comparison of the amino acid compositions of the purified free and bound forms of this protein with those of the E. coli free and bound lipoproteins.

Amino Acids↗

PubMed1978

The possible involvement of a plasmid(s) in actinomycin synthesis by Streptomyces parvulus and Streptomyces antibioticus.

The treatment of Streptomyces parvulus and Streptomyces antibioticus with acriflavine or novobiocin resulted in the loss of ability to produce actinomycin. The concomitant loss of ability to form aerial mycelium and the incidence of auxotrophic progeny (S. parvulus) were both low relative to the loss of the antibiotic-producing property. Protoplast fusion induced by polyethylene glycol 4000, using suitable auxotrophic strains of S. parvulus, resulted in high recombination frequencies to prototrophy (9.6 approximately 15%). When fusion was carried out between auxotrophic act+ and act- strains, respectively, there was a high frequency (84 approximately 95%) of the actinomycin synthesizing character among the prototrophic recombinants examined. No actinomycin-producing recombinant was detected in similar experiments between auxotrophic non-producing strains.

Dactinomycin↗

PubMed1978