Expression and rapid one-step purification of biologically active His-tagged factor C by Ni(2+) affinity column chromatography

Factor C is an unusual extracellular protein capable of inducing cytodifferentiation in certain Streptomyces strains. The protein is produced by Streptomyces griseus 45H at such a low amount that the study of its mode of action was hindered by the shortage of purified protein. We report here the expression of C-terminally hexa-His-tagged factor C in Streptomyces lividans and Escherichia coli. Expression in S. lividans is low while in E. coli it is relatively high, yielding about 5--10 mg of biologically fully active protein per liter culture.

Identification of factor C protein from Streptomyces griseus by microelectrospray mass spectrometry

Factor C, an extracellular signal protein of cellular differentiation, was studied and significant homology was found to several zinc finger-type regulatory proteins. The complete amino acid sequence, deduced from the gene, that encodes the protein, did not support the hypothesis that this protein might be a zinc finger-type regulatory protein. However, a theoretical single nucleotide insertion in the gene can result in another similarly sized protein containing about 20 His residues, which would be responsible for the high zinc affinity of factor C. The protein sample was reduced, alkylated and then in-gel digested with trypsin. The peptide fragments were then separated by capillary chromatography and identified by microelectrospray mass spectrometry. Peaks of higher intensity were sequenced by tandem mass spectrometry. The identified peptide fragments and the measured molecular mass of factor C protein also confirmed the original sequence of protein, as there was no shift in the open reading frame.

Idiopathic scoliosis--new surgical methods or search for the reasons

Idiopathic scoliosis (IS) is a deformity of the spine whose aetiology is unknown despite of extensive clinical and basic research work. The significance of this disease lies in the consequences of a spine deformity (deformation of the chest, compromise of the cardio-pulmonar function, compression of the neurological elements, severe somatic and psychological sufferings). According to statistical data, one third of the idiopathic scoliotic cases progress and need surgical intervention. Cotrel and Dubousset introduced the three dimensional correction surgical method for the treatment of spine deformities in 1983 (CD method). The authors report on the application of the CD method for the treatment of IS from 1991 to date. After the operation of 36 patients they give an account of good results and report on the modifications of the surgical technique on the basis of their experiences. Aware of the late consequences of the surgical treatment of IS the authors started with the investigation of the aetiology of the disease in order to introduce a causal treatment. As for the aetiological background of IS, data on the role of heritable factors were relevant only. They gave a hint to start with studies aimed at the investigation of genetic determinants of the syndrome. I aberration of chromosome #10 [karyotype: inv(10)(p11q26)]. In one of the cases there was a multiple familial occurrence of the syndrome coupled with the same anomaly of the karyotype. The probands' father and grandfather all had the same pattern of scoliotic deformity and the same aberrant karyotype of chromosome #10 was found both in the proband and his father. Preparation of genomial DNA from peripheral blood of the patients was started. Fragment length polymorphism (RFLP) examination with PCR technique using oligonucleotide primers specific for chromosome #10 and for regulatory genes of left-right body assymetry is underway.

Amino acid sequence homology of factor C produced by Streptomyces griseus with regulatory proteins of zinc finger type

Factor C is a regulatory protein produced by Streptomyces griseus 45H. Factor C-like antigen can be detected in the most diverse species examined. It is also present in human serum with an average of 219.4 U/ml of narrow dispersion. The level of factor C-like antigen shows an increase in the sera of patients with different hepatic disorders (341 U/ml), some values being 3-7 times higher than normal (600-1500 U/ml). Correlation was found between the elevated antigen levels and the amount of the bilirubin in the sera of patients with liver cirrhosis. Amino acid sequence homology was found between factor C and zinc finger motifs of several known DNA binding proteins. In fact, factor C was successfully bound to and eluted from a Zn2+ affinity column. Our data show that factor C is probably a zinc finger type DNA binding protein.

A short GC-rich sequence involved in deletion formation of cloned DNA in E. coli

A spontaneous deletion probably caused by rec A independent recombination between short-direct repeat sequences was observed in pUC19 plasmid carrying a piece of Streptomyces genomic DNA after culturing in liquid medium. The deletion removed an unknown portion of the cloned DNA and the BamHI-EcoRI part of the multiple cloning site with an additional flanking 111 bp from the vector. At the junction a 13 bp GC-rich DNA sequence highly homologous to a known spontaneous deletion hotspot was found.

Phenotypic heterogeneity of the progeny of Streptomyces griseus conidia

In order to understand the complex ontogenetical processes, the development of Streptomyces (S.) griseus was applied as a model. The developmental cycle of S. griseus starts and ends as a conidium. In between, coenocytic mycelium develops which, if studied by cytomorphological or biochemical methods, exhibits conspicious heterogeneity. The hyphae develop into young, transient and old vegetative hyphae and different stages of reproductive forms. In developmentally blocked mutants these sequences of events appear mixed in all possible associations. It seems as if the program of development could be divided into several subprograms. The quantitative evaluation of the results show that the individual morphological markers exhibit certain independence from each other realized with a given probability. The conidia of S. griseus are also heterogeneous concerning all morphological and physiological traits examined so far (shape, size, light refraction, staining and shape of nucleoids with Feulgen, methyl green--pyronine, intensity and form of polysaccharide distribution, heat resistance, etc.). Kinetics of the survival curves of two S. griseus strains--a well-sporulating and its developmentally blocked mutant /24/--are different from each other, one has many more heat resistant conidia than the other but the kinetics of the survival curves of the two S. griseus strains indicate that spore populations of both react differently to heat treatment and heat resistance can be modeled by assuming the presence of two independent subpopulations of spores with different heat sensitivity. The emergence of two distinct subpopulations with (possibly) the same genetic make-up is designated: phenotypic segregation. Heat resistance is first of all species specific (genetically determined) but the epigenetic segregation seems to be characteristic of the developmental process. This process can in certain mutants be affected by environmental conditions and more importantly by the so-called autoregulators (A-factor and factor C). Factor C and A-factor are needed to normal development, if their quantity or the time of addition to the culture was not optimal, the quantity of spores decreased.

[Diagnostic errors in symptom-poor hyperthyroidism in the aged]

The diagnosis of hyperthyreoidism manifesting in the elderly meets difficulty in many cases. Lack of some characteristic symptoms observable in younger patients can be misleading. The authors summarize the data of ten clinical cases where the hyperthyreoidism appeared in occult form, reminding rather for heart disease or malignant tumours. The assay of thyroid hormones and the level of antithyreoglobulin and anti-thyreoid peroxidase antibodies was unavoidable in order to establish correct diagnosis. Though the early diagnosis and treatment may enhance the life expectancy of the patients and may considerably decrease the cardial and the consecutive cerebral complications. The authors analyse the reasons and possible pathomechanism of the formation of atypical hyperthyreoidism occurring in the elderly.

Detection and determination of factor C--a regulatory protein--in Streptomyces strains by antiserum and monoclonal antibody

Rabbit antisera and monoclonal antibodies were raised against factor C, a regulatory protein of Streptomyces griseus. ELISA and immunoblotting techniques suitable to determine and characterize factor C antigen was detected in all the 23 Streptomyces strains and variants examined thus far and in one Bacillus subtilis too. Depending on the strain analysed it has a molecular mass of 34,000 or 70,000 in mycelial homogenates. Most of factor C was found excreted into the cultivation medium. The quantity of factor C antigen in different Streptomyces strains showed great variation. Amy+ strains were usually good producers of factor C while Amy- were not. This was consistent with our assumption that factor C was an inducer of reproductive phase in Streptomyces.

In vivo studies on the age-dependent decrease of the rates of total and mRNA synthesis in the brain cortex of rats

The membrane hypothesis of aging (Zs.-Nagy, I., 1978, J. Theor. Biol. 75, 189-195) attributes the primary role in cellular aging to an age-dependent decrease of the passive potassium permeability of the cell membrane which is due most probably to free-radical damage of the membrane components. As a consequence, the intracellular and intranuclear ionic strength increases resulting in a condensation of the chromatin and a slowing down of the synthetic processes performed by the nucleus. In this concept it was of importance to reveal whether the rates of total and mRNA synthesis display any age-dependent alteration parallel with the change of membrane permeability of the brain nerve cells. Experiments were performed using tritiated uridine incorporation measurements and suitable preparation techniques in young, adult and old rats (1.5, 13 and 25 mth of age, respectively). Comparisons of the incorporation rates revealed a very considerable decrease in the rate of synthesis of both the total and polyadenylated RNA (polyA + RNA) between the ages of 13 and 26 mth. The old animals displayed only about 55 and 67% of the rate of synthesis for the 2 classes of RNA, respectively, as compared to the young and adult rats, if the results are expressed as dpm/mg RNA. However, the decreases are even more pronounced (34 and 41%) if the results are expressed on a dry weight basis. The results obtained are compatible with the membrane hypothesis of aging.

Cytoplasmic contaminants in Triton X-100 washed rat liver nuclei - a possible way of further purification

The presence of cytoplasmic contaminants is demonstrated in preparations of rat liver nuclei, even after washing with Triton X-100. They can be removed by incubation at 37 degrees C in a medium of low-salt concentration.

Age-dependent alterations of the rate of RNA synthesis in rat brain cell nuclei

Endogenous Mn2+ and Mg2+ activated RNA polymerase activity was measured in isolated cell nuclei of brain from rats of different age-groups. It was established that the activity of the nucleoplasmic RNA polymerase is maintained at the level of young animals up to an age of 16 months but is decreased after 24 months. The nucleolar RNA polymerase activity decreases already at 16 months and a higher ratio of the Mn2+:Mg2+ activated RNA polymerase activities has been found to be characteristic for the older animals. By means of stepwise sucrose density gradient centrifugation fractions were obtained from the nuclear preparations highly enriched in cell nuclei of neuronal and glial origin respectively. By measuring the activity of the nucleoplasmic and nucleolar RNA polymerases in these fractions it was found that the elevated ratio of the nucleoplasmic to nucleolar RNA polymerase activity at 16 months of age is a characteristic of the neuronal nuclei while the glial nuclei behave by the opposite manner. A parallelism existing between the age-dependent change of the endogenous RNA polymerase activity and that of perichromatic granules of rat brain cortical cells is discussed.

Oral tularemia vaccine in man

The presence of transamidinase (TA-se) was demonstrated in Streptomyces griseus strain 45 which does not produce streptomycin (SM). This enzyme is involved in the biosynthesis of streptidine, a component of the SM molecule. TA-se is generally thought to be present only in SM-producing Streptomyces strains. The recent results are, however, in agreement with out previous data which showed the presence of streptidine in the isolated cell wall of SM-nonproducing strain 45. The TA-se activity of this strain is very low, but we were able to increase it by addition of arginine or by increasing the incubation with myo -inositol. The addition of these substances to the cultures of SM-nonproducing S. griseus strains, which hitherto were deficient in TA-se, may serve as a method for detecting the presence of this enzyme. In an incubation system in which the hyphae of an SM-producing strain of S. griseus had been blended and separated by density gradient centrifugation, certain hyphal fractions had been combined, and their SM production and TA-se activity had been measured, we were unable to find any close correlation between TA-se activity and SM-producing capacity. The hyphal fractions and their combination did not show strict parallelism between TA-se activity and the level of SM production.

Change of resistance to lysozyme and ultrasonic disintegration of the mycelium of Streptomyces griseus under the influence of chelating agents and polyvalent cations

Mycelia of Streptomyces griseus strain No. 52-1 from a 2-day submerged culture pretreated with ethylenediaminetetraacetic acid (EDTA) were digested with lysozyme. The sensitivity of younger vegetative hyphae to lysozyme increased while that of older reproductive hyphae remained almost unchanged.EDTA or borate pretreatment increased resistance to ultrasonic disintegration in the case of 96-h mycelia from submerged culture. EDTA was most effective at a concentration of 10−5 M.The enhanced resistance to ultrasonic disintegration can be reversed by Mg2+ and Al3+ in a concentration of 10−5 M, while Ca2+ ions are ineffective.These results suggest the existence of a polyvalent-ion-dependent layer in the cell wall of streptomycetes. Such a layer would be exterior to the mucopeptide layer. Its thickness changes during the life cycle and it is most prominent in younger vegetative hyphae.

Antibiotic production of hyphal fractions of Streptomyces griseus. II. Streptomycin production of different fractions obtained by density gradient centrifugation

The streptomycin-producing activity (SPA) of hyphal fractions from washed mycelium of submerged cultures of Streptomyces griseus strain 52-1, as obtained by density gradient centrifugation, was investigated. Activity of the various fractions differed strongly in intensity. The highest SPA was evident in the unfractionated mycelium. A synergistic effect upon SPA was found in the interaction of cultures of different ages, and a 55% increase in yield was obtained by mixing the 48- and 72-hr cultures. A synergistic effect occurred in all combinations studied. By use of fractions obtained from 72-hr mycelium for inoculation, differences in streptomycin production were noted. Some inoculum fractions yielded a greater amount of streptomycin (36%) than the unfractionated mycelial inoculum.