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G Högenauer

Publications and source records attributed to G Högenauer.

At least 37 records · Page 2Linked to original sources
PubMed1992

Sequences of the envM gene and of two mutated alleles in Escherichia coli.

The nucleotide sequence of the Escherichia coli envM gene was determined. It codes for a protein of 262 amino acids. The sequences of the E. coli and Salmonella typhimurium EnvM proteins are 98% identical. Gene envM is preceded in E. coli by a 43-nucleotide-long structural element, termed 'box c', which occurs in several E. coli operons between structural genes. This sequence element is totally absent in S. typhimurium. Gene envM was mapped at coordinate position 1366.8 kb of the physical map of Kohara et al. (Cell, 1987, 50, 495-508). As in S. typhimurium, a Gly for Ser exchange at position 93 of the amino acid sequence leads to a diazaborine-resistant E. coli phenotype. A Ser for Phe exchange at position 241 of the EnvM protein results in a temperature-sensitive growth phenotype. Comparison of the EnvM amino acid sequence with sequences available in databases showed significant homology with the family of short-chain alcohol dehydrogenases.

Alcohol Dehydrogenase↗
PubMed1991

The gene encoding squalene epoxidase from Saccharomyces cerevisiae: cloning and characterization.

The gene (ERG1) encoding squalene epoxidase (ERG) from Saccharomyces cerevisiae was cloned. It was isolated from a gene library, prepared from an allylamine-resistant (AlR) S. cerevisiae mutant, by screening transformants in a sensitive strain for AlR colonies. The ERG tested in a cell-free extract from one of these transformants proved to be resistant to the Al derivative, terbinafine. From this result, we concluded that the recombinant plasmid in the transformant carried an allelic form of the ERG1 gene. The nucleotide sequence showed the presence of one open reading frame coding for a 55,190-Da peptide of 496 amino acids. Southern hybridization experiments allowed us to localize the ERG1 gene on yeast chromosome 15.

Allylamine↗
PubMed1991

Repression and derepression of conjugation of plasmid R1 by wild-type and mutated finP antisense RNA.

The finP gene of plasmid R1 is located between the genes traM and traJ, partially overlapping the first few nucleotides of the latter. It codes for a repressor of the conjugation system. The product of this gene is a small RNA of 72 nucleotides and, because it is transcribed from the opposite DNA strand, it is complementary to the 5' non-translated sequences, the ribosome-binding site, and the first two codons of traJ mRNA. The finP transcript is present in much higher concentrations in R1 than in R1-19 containing cells, the latter being a derepressed mutant of the former. A synthetic finP gene expressed from a synthetic lambda PL promoter markedly reduced the conjugation frequency of pDB12, a multicopy derivative of R1-19. Mutagenesis of finP showed that only finP loop II mutants have lost the ability to repress conjugation of R1-19 in trans. They are also the only ones which derepress conjugal DNA transfer of R1, probably by competing for the finO product, a molecule needed as corepressor for maximal activity. Mutations interrupting potential open reading frames of finP do not abolish finP repressor activity. Hence finP acts as an antisense RNA blocking the expression of the traJ gene by interacting with traJ mRNA through loop II.

Base Sequence↗
PubMed1991

The TraM protein of plasmid R1 is a DNA-binding protein.

The TraM protein of the resistance plasmid R1 was purified to homogeneity and used for DNA-binding studies. Both gel retardation- and footprint experiments showed that TraM specifically binds to DNA of plasmid R1 comprising the region between the origin of transfer and the traM gene. Several TraM molecules bind and, according to the footprint experiments, two distinct sites of specific binding exist. The two sites are separated from each other by 12 nucleotides and each contains an inverted repeat. DNase I protection assays showed that the initial TraM binding occurs at these palindromic sequences. At higher protein concentrations the lengths of the DNA segments protected by TraM were increased towards the traM gene. In one region this extension leads to binding of TraM protein at its own promoters.

Bacterial Proteins↗
PubMed1990

The sequences of genes bordering oriT in the enterotoxin plasmid P307: comparison with the sequences of plasmids F and R1.

The nucleotide sequences of the enterotoxin plasmid P307 transfer genes traM, finP, traJ, traY, and gene 19 were determined. Gene 19 is highly conserved; its product is very similar to that coded by the F and R1 plasmids. The TraM protein is similar in P307 and in F; the R1 sequence shows differences in the 40 N-terminal amino acids. The traJ product is very different in P307, F, and R1. The traY gene from P307, which in F is almost twice as long, is similar in size to that from R1. The finP RNA shows a high degree of homology with that from R1 and F, except for the two loop regions where base changes were observed. The genes coding for proteins, except traY, could be expressed in minicell- and T7 promoter-driven expression systems, whereas traJ and gene 19 could be expressed only in the latter system.

Amino Acid Sequence↗
PubMed1989

A stable core region of the tra operon mRNA of plasmid R1-19.

The degradation of the polycistronic tra-mRNA of the resistance plasmid R1-19 leads to the accumulation of a well defined series of stable mRNA species. The majority of the most stable mRNAs contains the message for the traA gene only. The differently sized stable mRNAs possess a common 3'terminus within the traL gene but vary at their 5' ends. The 3'terminus probably results from protection against exoribonucleases by a secondary structural feature. We propose that the 5' ends are generated by endoribonucleolytic cleavage. The stability of this part of the tra-mRNA exceeds 30 minutes and probably increases the rate of expression of the traA gene product propilin, the precursor of the sex pilus subunit. The expression of propilin and its processing into a protein of the molecular weight of mature pilin is demonstrated with the isolated gene. The sequence of the so far unknown genes traL and traE of R1-19 is presented.

Amino Acid Sequence↗
PubMed1989

envM genes of Salmonella typhimurium and Escherichia coli.

Conjugation and bacteriophage P1 transduction experiments in Escherichia coli showed that resistance to the antibacterial compound diazaborine is caused by an allelic form of the envM gene. The envM gene from Salmonella typhimurium was cloned and sequenced. It codes for a 27,765-dalton protein. The plasmids carrying this DNA complemented a conditionally lethal envM mutant of E. coli. Recombinant plasmids containing gene envM from a diazaborine-resistant S. typhimurium strain conferred the drug resistance phenotype to susceptible E. coli cells. A guanine-to-adenine exchange in the envM gene changing a Gly codon to a Ser codon was shown to be responsible for the resistance character. Upstream of envM a small gene coding for a 10,445-dalton protein was identified. Incubating a temperature-sensitive E. coli envM mutant at the nonpermissive temperature caused effects on the cells similar to those caused by treatment with diazaborine, i.e., inhibition of fatty acid, phospholipid, and lipopolysaccharide biosynthesis, induction of a 28,000-dalton inner membrane protein, and change in the ratio of the porins OmpC and OmpF.

Alleles↗
PubMed1988

Localization of the kdsA gene with the aid of the physical map of the Escherichia coli chromosome.

The isolation and analysis of two recombinant plasmids containing the kdsA gene from Escherichia coli chromosomal gene libraries is reported. The subfragments obtained from the inserts correspond to the fragment pattern around coordinate 1,282 kilobases of the physical map of the E. coli chromosome (Kohara et al. Cell 50:495-508, 1987). The kdsA gene has been located at coordinates 1,282 through 1,283 kilobases, corresponding to min 26.7 in the classical map coordinates. The kdsA gene is transcribed from this position toward the nearby nar gene.

Aldehyde-Lyases↗
PubMed1987

The kdsA gene coding for 3-deoxy-D-manno-octulosonic acid 8-phosphate synthetase is part of an operon in Escherichia coli.

The kdsA gene of Escherichia coli was sequenced. It consists of 284 codons and is the last gene of a larger transcription unit. The mRNA is terminated by a rho-independent termination signal with the potential to be active in both orientations. This region is followed by another termination signal which seems to be active in the opposite orientation. Upstream of the kdsA gene a second open reading frame (ORF) was found; both this and the kdsA gene are transcribed in the same mRNA molecule when coded from the chromosome. In a plasmid-carried insert transcription starts from a cryptic promoter within the ORF preceding the kdsA gene. This promoter is not active in the intact chromosome.

Aldehyde-Lyases↗
PubMed1987

The origin of transfer of P307.

The DNA fragment carrying the oriT region from the enterotoxin plasmid P307 was isolated and its polynucleotide sequence was determined. Using Southern hybridization assays with a synthetic oligonucleotide probe, the oriT region was identified on a 7.9-kb EcoRI fragment from P307. By ligating the fragment with the cloning vector pUC119, plasmid pAG10 was obtained. The physical map of the insert was determined and oriT was located on a 540-bp BglII/SalI fragment. After this fragment was subcloned into sequencing phages, the polynucleotide sequence was established. Part of the sequence proved to be almost identical to segments of the oriT regions of the plasmids F and R1; another neighboring region was very different among all three sequences. The polynucleotide sequence proximal to traM is highly similar to that of F but different from that of R1.

Base Sequence↗
PubMed1987

Effect of a diazaborine derivative (Sa 84.474) on the virulence of Escherichia coli.

The scope of selective inhibition of lipopolysaccharide (LPS) biosynthesis in virulent organisms with a diazaborine derivative (Sa 84.474) as a means to render them avirulent was explored. A serum resistant Escherichia coli 0111:B4 became serum sensitive following its cultivation in vitro in media containing 1.5 mg/l of Sa 84.474, a concentration shown previously to inhibit over 95% of normal LPS biosynthesis in its mutant J5 strain. An encapsulated E. coli 01:K1 was also converted to serum sensitivity. In addition, Sa 84.474-pretreatment increased the efficiency with which the previously resistant organisms were opsonized in normal human serum and subsequently phagocytosed by granulocytes. In vivo, intravenously inoculated, Sa 84.474-pretreated bacteria were rapidly removed from the blood circulation and were significantly (P less than 0.05) less virulent in inducing lethal peritoneal infections in mice (LD50 4.9 +/- 1 X 10(6) cfu) when compared to untreated control bacteria (LD50 2.2 +/- 0.97 X 10(6) cfu). The results suggest that the LPS plays an important role in the virulence of the two bacterial strains and imply that agents acting in a similar manner but with acceptable selective toxicity might be novel drugs for therapy of Gram-negative bacterial infections.

Animals↗
PubMed1986

The sequences of the traJ gene and the 5' end of the traY gene of the resistance plasmid R1.

The traJ gene and the 5' end of the neighbouring traY gene of the resistance plasmid R1 were sequenced. Both structural genes show relatively little homology with the corresponding sequences of the related F plasmid. At the amino acid level sufficient homology is detected to allow an assignment of the two genes in R1. In traJ two methionine codons have to be regarded as potential chain initiation signals. Because of the analogy with the F plasmid sequence the second ATG is believed to be the main translational start site. The traJ gene codes for 228 amino acids. The 5' untranslated region of the traJ gene of R1 is highly homologous to the corresponding sequence in F indicating that it fulfills an important role in regulation. The transcription of the traY-Z operon starts in the structural gene of traJ. The amino terminal part of the TraY protein shows only limited homology with the F factor counterpart. However, the few conserved amino acids are a strong indication that our sequence contains the traY gene of R1.

Amino Acid Sequence↗
PubMed1986

Cloning and characterization of the gene encoding 3-deoxy-D-manno-octulosonate 8-phosphate synthetase from Escherichia coli.

The cloning of the gene for Escherichia coli PL-2 2-keto-3-deoxy-D-manno-octonate 8-phosphate synthetase is reported. Positive transformants showed an increase of approximately three-fold in specific activity of the enzyme both in E. coli and in Salmonella typhimurium as host cells. A subclone containing a 1.5-kilobase PvuII fragment overproduced active enzyme. Minicell experiments that allow the detection of plasmid encoded proteins revealed an insert-coded single protein band of 34 kilodaltons.

Aldehyde-Lyases↗
PubMed1985

The traM gene of the resistance plasmid R1: comparison with the corresponding sequence of the Escherichia coli F factor.

The 7.7-kb EcoRI fragment of the resistance plasmid R1 contains the gene for the TraM protein. The sequence was identified by the presence of an open reading frame (ORF) which is preceded upstream by two promoter sequences. Both these promoters were found to be active, although the more distant one predominates, as was judged by the relative abundance of mRNA of the expected length. The TraM protein could be synthesized in an in vitro DNA-dependent protein synthesis system if the DNA of the corresponding region was supplied as template. Comparison of the traM genes of R1 and the F factor showed a high degree of similarity, although a number of mutations, especially near the 5' terminus, introduce specific amino acid (aa) changes. Two-thirds of the 3' sequences differ mainly in silent mutations; hence the aa sequence of the corresponding carboxy-terminal portion of the protein is highly conserved. The 5' and 3' untranslated regions of the mRNAs show little homology. One of the promoter regions, the ribosome-binding sequences, and the transcription termination sites are located at comparable positions but differ in details.

Amino Acid Sequence↗
PubMed1984

Preliminary studies on the induction of a 120 000 molecular weight protein in resident peritoneal macrophages by arachidonic acid.

Exogenous arachidonic acid induced the synthesis of a 120 000 molecular weight protein in resident peritoneal macrophages. The induction of this protein is specific to the presence of arachidonic acid in the culture medium and is not induced by the presence of other fatty acids, irrespective of their chain length or degree of unsaturation. The protein induced is not a secretory protein and is not formed as a result of the processing of preexisting proteins in macrophages. In addition to arachidonic acid, prostaglandin E2 also induced the synthesis of 120 000 molecular weight protein in macrophages.

Animals↗
PubMed1984

Cloning the origin of transfer region of the resistance plasmid R1.

The insertion of a 7.7-kb EcoRI fragment of the resistance plasmid R1 into pBR325 yielded a plasmid which is mobilizable by pDB12, a multicopy derivative of R1drd-19 lacking most of the resistance determinants. The vector alone was not mobilizable in this system. From this observation we conclude that we have cloned the origin of transfer (oriT) of R1. After inserting a 5.3-kb PvuII-EcoRI fragment of the 7.7-kb region into pUC9 the DNA was cleaved randomly with DNaseI and BamHI linkers were attached to the ends. A subsequent BamHI digestion and electrophoretic separation of the resulting DNA molecules by their size allowed us to generate an ordered series of stepwise shortened plasmids. Plasmids with a deletion of approximately 3400 bp could no longer be mobilized. Since the next larger plasmid with 284 additional base pairs could be mobilized, we are able to confine the oriT location within this extra nucleotide stretch. The DNA sequence of this region was determined. Dominant features within the DNA region are a high AT content and five inverted repeats, which might function as recognition or substrate sites for proteins of the conjugational transfer system.

Base Sequence↗
PubMed1982

Tiamulin resistance mutations in Escherichia coli.

Forty "two-step" and 13 "three-step" tiamulin-resistant mutants of Escherichia coli PR11 were isolated and tested for alteration of ribosomal proteins. Mutants with altered ribosomal proteins S10, S19, L3, and L4 were detected. The S19, L3, and L4 mutants were studied in detail. The L3 and L4 mutations did not segregate from the resistance character in transductional crosses and therefore seem to be responsible for the resistance. Extracts of these mutants also exhibited an increased in vitro resistance to tiamulin in the polyuridylic acid and phage R17 RNA-dependent polypeptide synthesis systems, and it was demonstrated that this was a property of the 50S subunit. In the case of the S19 mutant, genetic analysis showed segregation between resistance and the S19 alteration and therefore indicated that mutation of a protein other than S19 was responsible for the resistance phenotype. The isolated ribosomes of the S19, L3, and L4 mutants bound radioactive tiamulin with a considerably reduced strength when compared with those of wild-type cells. The association constants were lower by factors ranging from approximately 20 to 200. When heated in the presence of ammonium chloride, these ribosomes partially regained their avidity for tiamulin.

Bacterial Proteins↗