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G Mastromei

Publications and source records attributed to G Mastromei.

At least 19 recordsLinked to original sources
PubMed2001

Clostridium felsineum and Clostridium acetobutylicum are two distinct species that are phylogenetically closely related.

The gene sequences encoding the 16S rRNA of Clostridium felsineum DSM 794T and NCIMB 10690T were determined. Both sequences exhibited a relatively very low degree of similarity to the previously determined 16S rRNA gene sequence from C. felsineum DSM 794T. C. felsineum is a member of the major Clostridium cluster, cluster I, and is phylogenetically closely related to Clostridium acetobutylicum. DNA-DNA hybridization results clearly indicated that C. felsineum and C. acetobutylicum belong to distinct species.

Clostridium↗
PubMed2000

Do bacterial cryptic genes really exist?

Cryptic genes have been defined as phenotypically silent DNA sequences, usually not expressed during the life cycle of a microorganism, but capable of expression in a few members of a large population by mutation, recombination, insertion processes, or other genetic mechanisms. Recently, the crypticity of several genetic systems has been questioned. It appears that in many cases cryptic genes are silent only under the experimental conditions analysed and that their expression can be induced in the natural environment. Therefore, we propose that cryptic genes might not be a peculiar class of uniquely regulated genes, but rather genes encoding unusual functions.

Acetolactate Synthase↗
PubMed1999

A putative sigma factor from Streptomyces sp. strain A21 can activate the expression of the cryptic operon bgl in Escherichia coli K-12.

Streptomyces sp A21 is a cellulolytic strain isolated from soil which was assigned to the genus Streptomyces on the basis of distinctive morphological features. A genomic library of A21 DNA has been constructed and transformed into Escherichia coli K-12 using a high-copy-number vector. One of the recombinant plasmids activates the cryptic bgl operon when inserted into appropriate strains. The complete sequence of the 1629-bp A21 DNA fragment has been determined. The analysis revealed the presence of an ORF whose putative product shows a high degree of similarity to RNA polymerase sigma factors; we therefore designated the gene psfS (Putative sigma factor, Streptomyces). Mapping of the 5' terminus of transcript by primer extension indicated that PsfS induces transcription initiation within the bgl promoter-silencer region.

Amino Acid Sequence↗
PubMed1999

Bacterial bio-mediated calcite precipitation for monumental stones conservation: methods of evaluation.

The weathering of monumental stones is a complex process inserted in the more general 'matter transformation cycle' operated by physical, chemical and biological factors. The consequence of these combined actions is a loss of cohesion with dwindling and scaling of stone material and the induction of a progressive mineral matrix dissolution. In the case of calcareous stones, calcite leaching increases the material porosity and decreases its mechanical features with a general weakening of the superficial structural strength. Attempts to stop, or at least to slow down, deterioration of monumental stones has been made by conservative treatments with both inorganic or organic products. More recent studies show a new approach to hinder these phenomena by inducing a bio-mediated precipitation of calcite directly inside the stone porosity. This can be achieved either through the application of organic matrix macromolecules extracted from sea shells or of living bacteria. The effectiveness of the treatment using calcinogenic bacteria has been evaluated with laboratory tests specifically developed to evaluate the parameters such as : porosity, superficial strength and chromatic changes, influenced by the treatment itself. The results obtained seem to indicate that this type of treatment might not be suitable for monumental stone conservation.

Bacteria↗
PubMed1998

Construction of a new vector conferring methotrexate resistance in Nicotiana tabacum plants.

A new binary vector encoding for Candida albicans dihydrofolate reductase (DFR1) has been constructed and used as a dominant selectable marker for plant transformation. Transgenic tobacco plants with an increased resistance to methotrexate (Mtx) were obtained by co-transformation of tobacco leaf discs with Agrobacterium tumefaciens strains carrying two new binary vectors: pTI20 and pTI18. Co-transformants of Nicotiana tabacum were directly selected for and rooted on medium containing both kanamycin (kan) and Mtx. Leaf discs of transgenic plants were assayed for capacity of regeneration at different Mtx concentrations. Analysis of transcripts was performed on total RNA extracted from two Mtx-resistant plants. The transgenic plants increased resistance to Mtx can be explained by the exceptionally low capacity of Mtx to bind C. albicans dihydrofolate reductase, accountable by the presence of two amino acid residues strategically important in Mtx binding.

Agrobacterium tumefaciens↗
PubMed1997

Isolation and characterization of a gene encoding alpha-tubulin from Candida albicans.

A gene encoding the alpha-tubulin of Candida albicans has been cloned and characterized. Nucleotide sequence analysis reveals the presence of an intron within the structural gene and predicts the synthesis of a polypeptide of 448 amino acid residues. Comparison of nucleotide and amino acid sequences with the Saccharomyces cerevisiae alpha-tubulin encoding genes shows a 75% homology and about 92% similarity respectively. In contrast to S. cerevisiae, C. albicans appears to possess only one gene for alpha-tubulin which is able to functionally complement a S. cerevisiae cold-sensitive tub1 mutant.

Amino Acid Sequence↗
PubMed1997

Restriction enzyme and DNA hybridization analysis of cellulolytic Streptomyces isolates of different origin.

Streptomyces rochei A2 endoglucanase (eglS) and beta-glucosidase (bgs1) genes were used as probes to survey their distribution among 16 Streptomyces strains isolated from different sources and characterized for their cellulolytic activities. The eglS probe hybridized to the genomic DNA of 12 strains with a restriction pattern different from that of S. rochei A2. The DNA from all strains, except one, hybridized with the bgs1 probe and one strain showed the same restriction pattern as seen in S. rochei A2. The sequence localized by the eglS probe in S. thermoviolaceus and the one localized by the bgs1 probe in strain EC1 were cloned and expressed in E. coli in plasmids pTAE and pCSF203, respectively. The restriction maps showed that the cloned genes were identical to eglS and bgs1. The restriction enzyme analysis and genomic DNA from all the strains identified nine different groups, each characterized by a distinctive pattern and in agreement with the results of the hybridization experiments.

DNA, Bacterial↗
PubMed1994

Characterization and sequence analysis of a Streptomyces rochei A2 endoglucanase-encoding gene.

A 7-kb fragment of Streptomyces rochei A2 chromosomal DNA was cloned into pAT153 and shown to confer endoglucanase (EglS) activity on Escherichia coli cells. In E. coli clones, the EglS was secreted into the periplasm. Deletion analysis revealed that an 827-bp fragment was enough for the enzymatic activity. Sequence analysis showed that the 827-bp fragment codes for the catalytic domain of the enzyme. The complete sequence of the gene (eglS) is 1149-bp long. A signal peptide, a catalytic domain and a cellulose-binding domain were identified from the nucleotide sequence, and the EglS found to belong to the family H of cellulase catalytic domains. These conclusions were substantiated by determination of the N-terminal sequence of the purified protein and zymogram analysis, which revealed protein species with a molecular mass equal to that deduced from the nt sequence analysis.

Amino Acid Sequence↗
PubMed1994

Sequence of a dihydrofolate reductase-encoding gene from Candida albicans.

The nucleotide (nt) sequence of the dihydrofolate reductase (DHFR)-encoding gene (DFR1) of Candida albicans was determined. The gene contains an open reading frame of 576 nt, coding for a protein of 192 amino acid (aa) residues (calculated M(r) 22,222), that is 38.5 and 31% similar to the Saccharomyces cerevisiae and human enzymes, respectively. The first 36 residues, at the N terminus, of the deduced aa sequence are identical to those determined by sequencing of the purified enzyme from C. albicans. Putative transcription start points were also determined. Restriction-fragment-length polymorphism analysis of the DFR1 chromosomal region suggests the presence of a single copy of the gene per haploid genome and shows a limited variability among the different C. albicans strains tested.

Amino Acid Sequence↗
PubMed1991

A dihydrofolate reductase gene from Candida albicans: molecular cloning.

The dihydrofolate reductase gene from Candida albicans has been cloned and partially characterized. A genomic bank from C. albicans strain 10127/5 was constructed in Escherichia coli and screened for trimethoprim resistance. A plasmid pMF1, carrying the resistance marker was isolated and characterized by restriction mapping and Southern blotting. Cells harbouring pMF1 were as sensitive as the parental cells to a wide spectrum of antibacterial agents, except for trimethoprim; the dihydrofolate reductase activity from these cells was trimethoprim resistant.

Candida albicans↗
PubMed1991

A bactericidal protein in Bombina variegata pachypus skin venom.

The skin venom of the yellow bellied toad Bombina variegata pachypus has an antimicrobial activity which seems to be correlated to the presence of a 6700 mol. wt polypeptide. This polypeptide was purified by electroelution from SDS-urea-polyacrylamide gels and characterized for its antimicrobial activity. A bactericidal action was detected at concentrations with little or no cytolytic effect. The determination of the Minimal Inhibitory Concentration showed that there was activity against gram positive and gram negative bacteria and also against yeasts. The skin secretions of three other anuran species (Bufo viridis, Hyla arborea and Discoglossus pictus) were examined for the presence of antimicrobial activities. Only the Hyla arborea secretion exhibited antimicrobial properties. A small amount of a 6700 mol. wt polypeptide was detected among the Hyla secreted products.

Amphibian Venoms↗
PubMed1989

Isolation of Bacillus subtilis transformation-deficient mutants and mapping of competence genes.

We have isolated and characterized 48 Bacillus subtilis competence-deficient mutants. The mutants, obtained by nitrosoguanidine mutagenesis or by insertional mutagenesis with transposon Tn917, had a reduced transformation frequency and a wild-type transduction frequency. The com mutations were mapped by PBS1 transduction and at least four new com genes have been identified. The mutants were also characterized for their capacity to bind and take up the transforming DNA.

Bacillus subtilis↗
PubMed1987

A low molecular weight protein with antimicrobial activity in the cutaneous 'venom' of the yellow-bellied toad (Bombina variegata pachypus).

The cutaneous 'venom' was collected from dorsal skin fragments of the yellow-bellied toad Bombina variegata pachypus by means of stimulation with noradrenaline. Light and electron microscope observations gave evidence that the 'venom' corresponds to the secretory products of both serous gland types (i.e. with small or large granules) characteristic of this genus, which had discharged their contents upon stimulation. The serous 'venom', when tested for antimicrobial activity, inhibited the growth of several bacterial strains. Heat treatment, dialysis, protease digestion and SDS-PAGE electrophoresis showed that the antimicrobial activity was thermostable and associated with a low molecular weight protein. This protein was purified and homogeneity determined by CM-cellulose chromatography and SDS-PAGE electrophoresis. The purified protein has a molecular weight of 6700, displays antibacterial properties and appears different from the antimicrobially active peptides previously isolated from the 'venom' of the toad.

Animals↗
PubMed1985

Competence proteins in Bacillus subtilis com mutants.

The synthesis of nucleases and proteins specific for competence development have been studied in four different Bacillus subtilis competence-deficient mutants. The nuclease analysis showed that two DNA-binding-deficient mutants were impaired in three nuclease activities involved in binding and entry of donor DNA. The other two strains did not show any reduction in nuclease activities. Two-dimensional gel electrophoresis of the proteins, synthesized during competence development, revealed that all four mutants are lacking several competence-specific polypeptides. Our data show that these com mutations have a strong pleiotropic effect, which could be due to a block in the metabolic pathway leading to competence development.

Bacillus subtilis↗
PubMed1984

Structural and functional heterogeneity of single-stranded DNA-binding proteins from calf thymus.

A new purification technique for 'single-stranded DNA-binding proteins' from calf thymus permits the demonstration of a considerable heterogeneity within these proteins. Several molecular species are obtained with Mr between 24.10(3) and 30.10(3) and pI values between 6 and 8, showing significant differences with regard to the following functional properties: strength of binding to single-stranded DNA; lowering of melting temperature of poly[d(A-T)]; stimulation of DNA polymerase alpha on a poly[d(A-T)] template. Analysis of trypsin digestion products demonstrates that the different molecular species share extensive primary sequence homology. Experiments with antibodies show that the different molecular species are antigenically related and that a 31 kDa protein present in low amounts in our preparations is very cross-reactive.

Animals↗
PubMed1984

Isolation and characterization of Bacillus subtilis mutants altered in competence.

We isolated and characterized four Bacillus subtilis competence-deficient mutants. The mutants were obtained by nitrosoguanidine mutagenesis and by screening for mutants unable to be transformed both on solid and in liquid medium. Most of the mutants obtained in this way were tested for their sensitivity to the DNA-damaging agents methyl methanesulfonate, mitomycin C, and UV light. Among the mutants which did not show an increased sensitivity to these agents, four were chosen for further characterization. Data were obtained which indicate that the mutants are reduced in chromosomal and plasmid transformation and in transfection, whereas they are not altered in transduction and in protoplast transformation. Transformation experiments carried out by mixing a culture of a mutant with a culture of a wild-type strain gave some complementation for competence with one of the strains. The mutants were also characterized for their capacity to bind, take up, and break down transforming DNA; furthermore, the four competence mutations were mapped, and the results indicate that they belong to four different genes.

Bacillus subtilis↗