Assembly of Bacillus subtilis phage phi29. 1. Mutants in the cistrons coding for the structural proteins.

The effect of mutations in the cistrons coding for the phage structural proteins has been studied by analyzing the phage-related structures accumulated after restrictive infection. Infection with susmutants in cistron 8, lacking both the major head and the fiber protein, does not produce any phage-related structure, suggesting a single route for the assembly of phage phi29; infection with ts mutants in this cistron produces isometric particles. Mutants is cistron 9, coding for the tail protein, TP1, produce DNA-free prolate heads with an internal core; these particles are abortive and contain the head proteins HPO, HP1 and HP3, the upper collar protein NP2 and the nonstructural proteins p7, p15 and p16. Mutants in cistron 10, coding for the upper collar protein, NP2, produce DNA-free isometric heads also with an internal core; they contain the head proteins and the nonstructural protein p7, suggesting that this protein forms the internal core. Mutants in cistrons 11 and 12, coding for the lower collar protein, NP3, and the neck appendages, NP1, respectively, give rise to the formation of DNA-containing normal capsids and DNA-free prolate particles, more rounded at the corners than the normal capsids and with an internal core; the DNA-containing 11-particles are formed by the head proteins and the upper collar protein; the DNA-free 11-particles contain, besides these proteins, the nonstructural protein p7 and a small amount of proteins p15 and 16. The DNA-containing 12-particles have all the normal phage structural proteins except the neck appendages, formed by protein NP1; the DNA-free particles are similar to the DNA-free 11-particles. After restricitive infection mutant sus14(1241) has a delayed lysis phenotype and produces a phage burst higher than normal, after artificial lysis. It produces DNA-containing particles, identical to wild-type phage, which have all the normal phage structural proteins, and DNA-free prolate particles, more rounded at the corners than the final phage particles and with an internal core; the last particles contain the same proteins as the DNA-free 11 or 12-particles. These particles could represent a prohead state, ready for DNA encapsulation. None of the DNA-containing particles have the nonstructural proteins p7, p15 or p16, suggesting that these proteins are released from the proheads upon DNA encapsulation.     

Relationship between the structure of carbonylcyanide phenylhydrazones and inhibition of growth of microorganisms,stimulation of respiration of yeast cells and rat liver mitochondria

The effect of ten derivatives of carbonylcyanide phenylhydrazone on growth of bacteria, yeast and different species of filamentous fungi was investigated. In yeast and mitochondria isolated from rat liver the effect of these derivatives on the respiratory activity was also followed. The relative efficiency of the individual derivatives of earbonylcyanide phenylhydrazone was determined on the basis of the results obtained. It was shown that derivatives, in which the substituent on the benzene ring causes simultaneously an increase of acidity and lipophilicity of the derivative as compared with the non-substituted carbonylcyanide phenylhydrazone (4-trifluoromethoxy-, 3-chloro-, 4-chloro and 3,4-dichloroderivatives) were most effective.     

Separation and properties of α-mannosidase and mannanase from the basidiomycetePhellinus abietis

Proteins of a crude enzyme preparation obtained from the cultivation medium of the basidiomycetePhellinus abietis were separated by gel filtration and ion-exchange chromatography. The preparation contained a minimum of three enzymes capable of splitting α-d-mannosidic bonds: α-mannosidase, exomannanase, and endomannanase, which were separated. Some properties of the mannanase complex of the crude enzyme preparation, and of a partially purified α-mannosidase were examined. The mannanase complex exhibited two pH optima, its temperature optimum being at 46 °C The pH optimum of purified α-mannosidase was at pH 5.0, the temperature optimum was at 60 °C; the enzyme had a relatively high heat stability. The K_m of α-mannosidase forp-nitrophenyl α-d-mannopyranoside was 1.5 x 10⁻⁵ M. Pure α-mannosidase did not split mannan.     

Strain improvement inStreptomyces galilaeus,a producer of anthracycline antibiotics galirubins

The production of ε-pyrromycinone glycosides inStreptomyces galilaeus increased 12-fold, with respect to the wild strain, as a result of a sequential procedure including both natural selection and treatment with mutagens (nitrous acid, UV light and γ-irradiation). Nitrous acid exhibited the highest mutagenic effect, both in increasing the productivity and in inducing blocked mutants. A mutant strain blocked in the biosynthesis of glycosides and accumulating free ε-pyrromycinone as the principal metabolite was obtained.     

Transformation inBacillus subtilis. Initial stages of the transformation process and their energy dependence

NaN₃ was found to inhibit transformation but not the irreversible binding of donor³H-DNA in competent cells of the original low-transformable strainBacillus subtilis 168trp ₂ . Addition of NaN₃ to cells of two mutantsBacillus subtilis HT39 and HT46 with an increased transformability decreased substantially the irreversible binding of the donor DNA to the competent cells. The decreased irreversible binding of DNA is caused by an increased osmotic sensitivity of competent cells of the mutants HT39 and HT46 in the presence of NaN₃, leading preferentially to lysis of the competent cells.     

Simultaneous and successive induction of synthesis of β-Galactosidase and tryptophanase inEscherichia coli K 12 in the chemostat

β-Galactosidase and tryptophanase were induced either simultaneously or successively during continuous cultivation of the inducible strainEscherichia coli K 12 in the chemostat. Growth was limited by glycerol and the dilution rate was 0.1 h⁻¹. During both the simultaneous and successive induction specific rates of synthesis, as well as maximum enzyme levels, were identical with those obtained after independent induction of individual enzymes. As compared with batch cultivation, β-galactosidase reached the same specific rate of synthesis in the chemostat, whereas the specific rate of synthesis of tryptophanase in the chemostat was up to five times higher.     

Transforming activity of plasmid and chromosomal DNA inEscherichia coli

An auxotrophic strain ofEscherichia coli with therecB recC sbcB genotype was transformed by chromosomal DNA of the prototrophic strain and by plasmid DNA carrying genes for antibiotic resistance (R1drd 19). The donor plasmid DNA obtained by cell lysis in the presence of Triton X-100 and subsequent centrifugation in a caesium chloride-ethidium bromide gradient was shown to have a circulaf molecule and to retain its completeness after penetration into the recipient. Experiments with mixtures or plasmid and chromosomal DNA indicate a competition between these two DNA types during the transformation reaction in the given system.