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R Brückner

Publications and source records attributed to R Brückner.

At least 37 records · Page 2Linked to original sources
PubMed1996

Transcriptional regulation of the sucrase gene of Staphylococcus xylosus by the repressor ScrR.

In Staphylococcus xylosus, scrB is one of two genes necessary for sucrose utilization. It encodes a sucrase that hydrolyzes intracellular sucrose-6-phosphate generated by the uptake of sucrose via the sucrose-specific enzyme II of the phosphotransferase system, the gene product of scrA. ScrB sucrase activity is inducible by the presence of sucrose in the culture medium. Primer extension experiments demonstrated that the observed regulation is achieved at the level of scrB transcription initiation. The protein mediating sucrose-specific regulation of scrB was found to be encoded immediately upstream of the sucrase gene. The nucleotide sequence of the regulatory gene scrR comprises an open reading frame that specifies a protein of 35.8 kDa. This protein exhibits similarity to transcriptional regulators of the GalR-LacI family. Inactivation of the scrR reading frame in the genome of S. xylosus led to the constitutive expression of scrB at a high level, identifying ScrR as a repressor of transcription. Sucrose-specific regulation of scrB was also lost upon deletion of 4 bp of a palindromic sequence (OB) covering positions +6 to +21 downstream of the scrB transcriptional start site. These results suggested a direct interaction of the ScrR repressor and the operator OB. Accordingly, a fusion protein consisting of the maltose-binding protein of Escherichia coli and the ScrR protein was able to interact with an scrB promoter fragment in gel mobility shift experiments but failed to bind an scrB fragment carrying the 4-bp deletion derivative of OB. An scrR promoter fragment, which dose not contain a sequence resembling OB, was not shifted by the fusion protein. This result corroborates scrR primer extension analyses showing that transcription of the repressor gene itself is not regulated. Therefore, the sucrase gene operator OB is the target sequence through which the ScrR protein exerts its negative effect on transcription initiation. In the promoter region of scrA, the gene essential for sucrose transport, two palindromic sequences that are similar to the scrB operator are found. Their presence in scrA suggests that ScrR controls a sucrose-specific regulon in S. xylosus.

ATP-Binding Cassette Transporters↗
PubMed1995

Glucose kinase-dependent catabolite repression in Staphylococcus xylosus.

By transposon Tn917 mutagenesis, 16 mutants of Staphylococcus xylosus were isolated that showed higher levels of beta-galactosidase activity in the presence of glucose than the wild-type strain. The transposons were found to reside in three adjacent locations in the genome of S. xylosus. The nucleotide sequence of the chromosomal fragment affected by the Tn917 insertions yielded an open reading frame encoding a protein with a size of 328 amino acids with a high level of similarity to glucose kinase from Streptomyces coelicolor. Weaker similarity was also found to bacterial fructokinases and xylose repressors of gram-positive bacteria. The gene was designated glkA. Immediately downstream of glkA, two open reading frames were present whose deduced gene products showed no obvious similarity to known proteins. Measurements of catabolic enzyme activities in the mutant strains grown in the presence or absence of sugars established the pleiotropic nature of the mutations. Besides beta-galactosidase activity, which had been used to detect the mutants, six other tested enzymes were partially relieved from repression by glucose. Reduction of fructose-mediated catabolite repression was observed for some of the enzyme activities. Glucose transport and ATP-dependent phosphorylation of HPr, the phosphocarrier of the phosphoenolpyruvate:carbohydrate phosphotransferase system involved in catabolite repression in gram-positive bacteria, were not affected. The cloned glkA gene fully restored catabolite repression in the mutant strains in trans. Loss of GlkA function is thus responsible for the partial relief from catabolite repression. Glucose kinase activity in the mutants reached about 75% of the wild-type level, indicating the presence of another enzyme in S. xylosus. However, the cloned gene complemented an Escherichia coli strain in glucose kinase. Therefore, the glkA gene encodes a glucose kinase that participates in catabolite repression in S. xylosus.

Amino Acid Sequence↗
PubMed1995

Characterization of a genetic locus essential for maltose-maltotriose utilization in Staphylococcus xylosus.

A genetic locus from Staphylococcus xylosus involved in maltose-maltotriose utilization has been characterized. The chromosomal region was identified by screening a genomic library of S. xylosus in Escherichia coli for sucrose hydrolase activity. Nucleotide sequence analysis yielded two open reading frames (malR and malA) encoding proteins of 37.7 and 62.5 kDa, respectively. MalR was found to be homologous to the LacI-GalR family of transcriptional regulators, and MalA showed high similarity to yeast alpha-1,4-glucosidases and bacterial alpha-1,6-glucosidases. Inactivation of malA in the genome of S. xylosus led to a maltose-maltotriose-negative phenotype. In cell extracts of the mutant, virtually no glucose release from maltose and short maltodextrins was detectable. Inactivation of malA in a sucrose-6-phosphate hydrolase-deficient S. xylosus strain resulted in the complete loss of the residual sucrose hydrolase activity. The MalA enzyme has a clear preference for maltose but is also able to release glucose from short maltosaccharides. It cannot cleave isomaltose. Therefore, malA encodes an alpha-1,4-glucosidase or maltase, which also liberates glucose from sucrose. Subcloning experiments indicated that malA does not possess its own promoter and is cotranscribed with malR. Its expression could not be stimulated when maltose was added to the growth medium. Chromosomal inactivation of malR led to reduced maltose utilization, although alpha-glucosidase activity in the malR mutant was slightly higher than in the wild type. In the mutant strain, maltose uptake was reduced and inducibility of the transport activity was partially lost. It seems that MalR participates in the regulation of the gene(s) for maltose transport and is needed for their full expression. Thus, the malRA genes constitute an essential genetic locus for maltosaccharide utilization in S. xylosus

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of the scrA gene encoding the sucrose-specific Enzyme II of the phosphotransferase system from Staphylococcus xylosus.

By insertional mutagenesis with the staphylococcal transposon Tn551, mutants of Staphylococcus xylosus were isolated that were unable to utilize sucrose. One of these was found to be deficient in sucrose uptake. The genomic region containing this sucrose uptake gene of Staphylococcus xylosus (scrA) was cloned in Staphylococcus carnosus. The scrA gene was further localized to a 4.4 kb DNA fragment by complementation of the sucrose transport-deficient S. xylosus mutant. The DNA sequence analysis of the scrA region revealed three open reading frames, one of which encodes a protein of 480 amino acids (51.335 kDa) with significant similarity to sucrose-specific Enzymes II of phosphoenolpyruvate-dependent carbohydrate phosphotransferase systems (PTS). A protein with an apparent molecular weight of 50 kDa was obtained in Escherichia coli by expression of scrA with the bacteriophage T7 RNA polymerase promoter system. Transcriptional start sites of the scrA gene were localized by primer extension analysis to positions 46 and 49 nucleotides upstream of the scrA start codon. No additional sucrose utilization genes are encoded close to scrA on the S. xylosus chromosome.

Amino Acid Sequence↗
PubMed1993

High selectivity for inhibition of phosphodiesterase III and positive inotropic effects of MCI-154 in guinea pig myocardium.

MCI-154 (0.3-100 microM) exerted a concentration-dependent positive inotropic effect in isolated guinea pig papillary muscles (EC50 0.8 microM). The efficacy of MCI-154 (253% of predrug value) was 1.7-fold higher than that of saterinone but comparable to that of milrinone. Carbachol markedly reduced the increase in force of contraction (FOC) of MCI-154. In intact contracting papillary muscles, the positive inotropic effect was accompanied by an increase in cyclic AMP content to 0.78 +/- 0.09 pmol/mg wet weight (n = 10), corresponding to 150% of the basal value (0.51 +/- 0.05 pmol/mg wet weight, n = 21) in the presence of submaximal cyclic AMP phosphodiesterase (PDE) isoenzyme III inhibiting concentrations of MCI-154 (30 microM). MCI-154 (1-1,000 microM) concentration-dependently inhibited the activity of PDE III from homogenates of guinea pig myocardium. The IC50 was 3.8 microM. PDE I, II, and IV were not significantly affected up to 100 microM (PDE I and IV) and up to 1,000 microM (PDE II). In comparison, milrinone and saterinone were PDE III/IV-selective PDE inhibitors. Rolipram inhibited PDE IV only. IBMX and theophylline were nonselective PDE inhibitors. MCI-154 had only a marginal positive chronotropic effect. The frequency of spontaneously beating right auricles from guinea pig heart was increased by 8.7% at most (n = 5). MCI-154 increased Ca2+ sensitivity in chemically skinned porcine ventricular muscle fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Characterization of a sucrase gene from Staphylococcus xylosus.

The Staphylococcus xylosus gene scrB, encoding a sucrase, has been isolated from a genomic library of S. xylosus constructed in Escherichia coli. The gene was detected by its ability to confer utilization of the glucose and fructose residues of raffinose in an E. coli strain that is not able to metabolize galactose. It was found to reside within a 1.8-kb DNA fragment, the nucleotide sequence of which was determined. One large open reading frame, which is preceded by a ribosome binding site, is encoded on the fragment. Its deduced amino acid sequence yields a protein with a molecular mass of 57.377 kDa which shows significant homology with bacterial sucrose-6-phosphate hydrolases and sucrases. Overexpression of scrB in E. coli by the bacteriophage T7 polymerase promoter system resulted in the production of a protein with an apparent molecular mass of 58 kDa. Disruption of the scrB gene in the S. xylosus genome rendered S. xylosus unable to utilize sucrose. Thus, the ScrB sucrase is essential for sucrose metabolism in S. xylosus.

Amino Acid Sequence↗
PubMed1992

A series of shuttle vectors for Bacillus subtilis and Escherichia coli.

A series of shuttle vectors for Bacillus subtilis and Escherichia coli was developed. These are derived from one basic construct composed of parts of the Gram+ plasmid pUB110 and the Gram- plasmid pBR322. They contain multiple cloning sites flanked by transcriptional terminators. In one plasmid, a vegetative B. subtilis promoter drives transcription of inserted genes. For the construction of operon and gene fusions, the cat of pUB112 and the lacZ gene of E. coli were employed as reporter genes. With these vectors, cloning and expression of genes as well as probing of regulatory signals can be performed in B. subtilis and E. coli.

Bacillus subtilis↗
PubMed1992

Prevalence of cystic fibrosis mutations in the East German population.

A representative multicenter cystic fibrosis (CF) mutation analysis on about half of all known cystic fibrosis patients of the 5 East German Länder is reported. Analyses for 17 mutations, among them Delta F508, R553X, G542X, S549R,N,I, G551D, S1255X, R347P,H, and Y122X, were performed. As expected, the delta F508 mutation in exon 10 of the CFTR gene is the major gene alteration causing CF in our patients. However, in comparison to studies from Western Germany, a significantly lower percentage of just over 60% is found in our patients, resembling data obtained from slavonic populations. The severe phenotype of cystic fibrosis is most frequently associated with homozygosity for the delta F508 mutation. No particular allele association could be found with the intermediate and mild phenotypes of this disease. The next most frequent of the investigated mutations is R553X (13.3% of non-delta F chromosomes) followed by R347P (9.2%) and G542X (4.4%).

Cystic Fibrosis↗
PubMed1991

[Unusual perceptions with the Pola Test in a case of esotropia with anomalous correspondence].

That the Pola test figures of heterophoric subjects with fixation disparities are described as deformed at times, was published by H. J. Haase two decades ago. The main subject in this publication is a 13-year-old boy with early childhood convergent strabismus, in which the "squint therapy" which was used at that time, did not change the angle of squint and the anomalous correspondence to any extent. The corrected visual acuity was the same bilaterally, 1.0 to 1.1. If the esotropic eye position was corrected as well as possible with prisms to the objective angle, a change between diplopia and binocular fusion occurred; occasionally even to "normal corresponding" fusion with correct stereopsis. In the transition phases the test level appeared to be more or less drawn out in width, and the half figures underwent all kinds of "somersaults". Binocular macropsia and monocular micropsia and macropsia, and also polyopia and unusual depth effects were described. Confusion did not occur; all pictures had form. These rare phenomena were interpreted as a competition between established anomalous and latent normal correspondence. This communication should stimulate further observations of this type and, should the occasion arise, lead to experimental research.

Adolescent↗
PubMed1991

[Adenoma of the pigmented epithelium of the iris with endothelialization and descemetization in the horse].

The authors describe peculiar tumors with brown-white piebald anterior surface, which had grown bilaterally from the corpora nigra (C.N.) of an adult horse and occluded the pupils. The surgical procedure for removing the larger tumor and the postoperative treatment are described. The findings by light and electron microscopy suggest that the tumor represent a so-called adenoma of the iris pigment epithelium. The white patches on its surface consist of newly formed Descemet-like material produced by displaced corneal endothelial cells, which have probably grown on the tumor after contact with the posterior face of the cornea.

Adenoma↗
PubMed1991

[The polymerase chain reaction PCR and its use in genetic diagnosis].

In genomic diagnosis the ensemble of techniques has been recently expanded by the powerful method of the polymerase chain reaction (PCR). Using pairs of synthetic oligonucleotides for priming of synthesis and a thermoresistant DNA polymerase a millionfold amplification of target DNA sequences from patients provides DNA fragments for following investigations such as electrophoresis. The paper presents some examples of PCR application for diagnosis in cystic fibrosis and Duchenne muscular dystrophy.

Cystic Fibrosis↗
PubMed1990

[Hematobilia--a rare complication after traumatic liver rupture].

Hematobilia is a rare complication after traumatic liver injury and has a high mortality. Clinical signs are hyperbilirubinemia and increase of bile acids in serum by rarely increased liver enzymes. Pathophysiologically there is a connection between bile duct system and liver veins. To determine the diagnosis giving rise to the clinical signs, after abdominal ultrasonography and computed tomography the ERCP seems to be the most suitable method. The treatment of hematobilia is not necessarily operative; a successful conservative therapy is also possible.

Adult↗
PubMed1990

Multiple active forms of a novel serine protease from Bacillus subtilis.

We have cloned and sequenced a gene (epr) encoding a novel serine protease from Bacillus subtilis. Several active forms of the enzyme with molecular masses between 40 and 34 kDa were found in the medium of B. subtilis cultures containing the epr gene cloned on a plasmid. Deletions at the 3' end of the gene, removing up to 240 amino acids of the reading frame, abolished the expression of the larger species but did not affect the expression of the 34 kDa enzyme. The C-terminal third of the protein is therefore not required for protease activity. The size variation of the active forms expressed by the complete epr gene appears to be the result of partial removal of the C-terminus either by processing or degradation. Thus, the epr gene consists of two domains, one encoding a serine protease homologous to subtilisin and the other a C-terminus of unknown function.

Amino Acid Sequence↗
PubMed1990

[The significance of the preoperative CEA value for the prognosis of rectal cancer].

254 patients were operated for rectal carcinoma in the period from 1980 to 1986. The number of curative procedures, recurrence rate and 5-year-survival rate were dependent on the preoperative CEA levels, which correlated with the tumour stage. Even within tumour stages with enough cases for statistical evaluation the CEA could be established as an independent prognostical variable. Within stage pT2N0M0 recurrence rate for patients with preoperative CEA level below 5 ng/ml was 29% compared to 64% in patients with higher serum levels. Median survival time for the two groups were 65 and 35 months, respectively. In stage of lymph node involvement median survival times of 46 and 25 months were observed for the groups with CEA levels above and below 5 ng/ml. The pattern of recurrence within the two stages seemed to be unaffected by the preoperative CEA level. Patients with preoperative elevated CEA represent a risk group with need of consistent postoperative follow-up and CEA controls.

Carcinoembryonic Antigen↗
PubMed1990

First analysis of the F508 deletion in cystic fibrosis patients from the GDR.

Cystic fibrosis (CF) patients (n = 157) from the GDR were analysed for the occurrence of the recently discovered 3bp deletion causing CF. About 50% of all investigated patients were homozygotes and about 30% heterozygotes for this deletion. Of the analysed CF chromosomes from these patients, 62% carry the deletion, which is in strong linkage disequilibrium with the KM19 restriction fragment length polymorphism allele 2 and the 1/2 XV2c/KM19 haplotype.

Chromosome Deletion↗