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H Küntzel

Publications and source records attributed to H Küntzel.

At least 37 records · Page 2Linked to original sources
PubMed1983

Mitochondrial polypeptide elongation factor EF-Tu of Saccharomyces cerevisiae. Functional and structural homologies to Escherichia coli EF-Tu.

The polypeptide elongation factor EF-Tu was isolated from a mitochondrial 100 000 x g supernatant of the yeast Saccharomyces cerevisiae and purified over 880-fold by DEAE-Sephadex chromatography and gel filtration. The factor efficiently replaces bacterial EF-Tu in a phenylalanine polymerizing cell-free system of Escherichia coli, it binds GDP and it protects phenylalanyl-tRNA against hydrolysis of the ester bond in the presence of 10 mM GTP. The polymerizing activity of the mitochondrial factor is inhibited to 90% by 50 microM N-ethylmaleimide and to 50% by 2.5 microM kirromycin. The purified factor contains two major polypeptides of apparent molecular weights 48 000 and 34 000. Antibodies raised against the 48 000-Mr protein react with EF-TuE. coli, as revealed by immune blotting and by the inhibition of phenylalanine polymerization. No reaction was observed between anti-(34 000-Mr) and 48 000-Mr protein or EF-TuE. coli. The 48 000-Mr protein has the same isoelectric point (pI = 6.2) and a content of cysteine and basic amino acids similar to the bacterial EF-Tu. It is concluded that the 48 000-Mr protein is the analogue to EF-TuE. coli, and that yeast mitochondrial EF-Tu is functionally and structurally more related to bacterial EF-Tu than cytosolic EF-1 of the same cell.

Chemical Phenomena↗
PubMed1983

Consensus structure and evolution of 5S rRNA.

A consensus structure model of 5S rRNA presenting all conserved nucleotides in fixed positions has been deduced from the primary and secondary structure of 71 eubacterial, archaebacterial, eukaryotic cytosolic and organellar molecules. Phylogenetically related groups of molecules are characterized by nucleotide deletions in helices III, IV and V, and by potential base pair interactions in helix IV. The group-specific deletions are correlated with the early branching pattern of a dendrogram calculated from nucleotide substitution data: the first major division separates the group of eubacterial and organellar molecules from a second group containing the common ancestors of archaebacterial and eukaryotic/cytosolic molecules. The earliest diverging branch of the eubacterial/organellar group includes molecules from Thermus thermophilus, T. aquaticus, Rhodospirillum rubrum, Paracoccus denitrificans and wheat mitochondria.

Bacteria↗
PubMed1982

Nucleotide sequence of Aspergillus nidulans mitochondrial genes coding for ATPase subunit 6, cytochrome oxidase subunit 3, seven unidentified proteins, four tRNAs and L-rRNA.

The complete nucleotide sequence of a 14 kb segment of A. nidulans mtDNA reveals a rather compact organization of genes transcribed from the same strand and coding for two functionally known proteins, seven unidentified polypeptides (URFs), 24 tRNAs and two rRNAs. One of the URFs is located in the intron of the L-rRNA gene and codes for a basic protein of 410 residues. The other URFs are in spacer regions and code for hydrophobic proteins. URFa is homologous to human URF4, and URFb produces a polypeptide of 48 residues resembling the human URF6L product (hydrophobic N-terminus, basic C-terminus). The ATPase subunit 6 genes from mitochondria and E. coli appear to share a common ancestor. The codon frequencies of identified genes and URFs are similar, and codons ending with G or C are rarely used. The structures of tRNAs specific for arginine, asparagine, tyrosine and histidine are deduced from gene sequences.

Adenosine Triphosphatases↗
PubMed1982

Mitochondrial L-rRNA from Aspergillus nidulans: potential secondary structure and evolution.

The alignment of gene sequences coding for A. nidulans mitochondrial L-rRNA and E. coli 23S rRNA indicates a strong conservation of primary and potential secondary structure of both rRNA molecules, except that homologies to the 5'-terminal 5.8S-like region and the 3'-terminal 4.5S-like region of bacterial rRNA are not detectable on mtDNA. The structural organization of the A. nidulans mt L-rRNA gene corresponds to that of yeast omega + strains: both genes are interrupted by a large intron sequence (1678 and 1143 bp, respectively) and by another smaller insert (91 and 66 bp) at homologous positions within domain V. An evolutionary tree derived from conserved L-rRNA gene sequences of yeast nuclei, E. coli, maize chloroplasts and six mitochondrial species exhibits a common root of organelle and bacterial sequences separating early from the nuclear branch.

Animals↗
PubMed1981

Nucleotide sequence of the Aspergillus nidulans mitochondrial gene coding for the small ribosomal subunit RNA: homology to E. coli 16S rRNA.

The complete primary structure of the 1437 bp gene coding for mitochondrial 15S rRNA and its flanking regions was determined by Maxam-Gilbert sequencing of cloned HindIII fragment H3 of A. nidulans mtDNA. The gene product reveals significant homology (59%) to E. coli 16S rRNA, and the potential secondary structures of both rRNA molecules are very similar, except that the hairpin structures 7, 8 and 30 of the Brimacombe 16S rRNA model are deleted, and that two sequences of 8 and 31 nucleotides are inserted in the mitochondrial species.

Aspergillus nidulans↗
PubMed1981

Nucleotide sequence of 5S ribosomal RNA from Aspergillus nidulans and Neurospora crassa.

The nucleotide sequences of 5S rRNA molecules isolated from the cytosol and the mitochondria of the ascomycetes A. nidulans and N. crassa were determined by partial chemical cleavage of 3'-terminally labelled RNA. The sequence identity of the cytosolic and mitochondrial RNA preparations confirms the absence of mitochondrion-specific 5S rRNA in these fungi. The sequences of the two organisms differ in 35 positions, and each sequence differs from yeast 5S rRNA in 44 positions. Both molecules contain the sequence GCUC in place of GAAC or GAUY found in all other 5S rRNAs, indicating that this region is not universally involved in base-pairing to the invariant GTpsiC sequence of tRNAs.

Aspergillus nidulans↗
PubMed1981

Phylogenetic tree derived from bacterial, cytosol and organelle 5S rRNA sequences.

A phylogenetic tree was constructed by computer analysis of 47 completely determined 5S rRNA sequences. The wheat mitochondrial sequence is significantly more related to prokaryotic than to eukaryotic sequences, and its affinity to that of the thermophilic Gram-negative bacterium Thermus aquaticus is comparable to the affinity between Anacystis nidulans and chloroplastic sequences. This strongly supports the idea of an endosymbiotic origin of plant mitochondria. A comparison of the plant cytosol and chloroplast sub-trees suggests a similar rate of nucleotide substitution in nuclear genes and chloroplastic genes. Other features of the tree are a common precursor of protozoa and metazoa, which appears to be more related to the fungal than to the plant protosequence, and an early divergence of the archebacterial sequence (Halobacterium cutirubrum) from the prokaryotic branch.

Bacteria↗
PubMed1980

Physical map of Aspergillus nidulans mitochondrial genes coding for ribosomal RNA: an intervening sequence in the large rRNA cistron.

A detailed map of the 32 kb mitochondrial genome of Aspergillus nidulans has been obtained by locating the cleavage sites for restriction endonucleases Pst I, Bam H I, Hha I, Pvu II, Hpa II and Hae III relative to the previously determined sites for Eco R I, Hind II and Hind III. The genes for the small and large ribosomal subunit RNAs were mapped by gel transfer hybridization of in vitro labelled rRNA to restriction fragments of mitochondrial DNA and its cloned Eco R I fragment E3, and by electron microscopy of RNA/DNA hybrids. The gene for the large rRNA (2.9 kb) is interrupted by a 1.8 kb insert, and the main segment of this gene (2.4 kb) is separated from the small rRNA gene (1.4 kb) by a spacer sequence of 2.8 kb length. This rRNA gene organization is very similar to that of the two-times larger mitochondrial genome of Neurospora crassa, except that in A. nidulans the spacer and intervening sequences are considerably shorter.

Aspergillus nidulans↗
PubMed1980

Amplification of a mitochondrial DNA sequence in the cytoplasmically inherited 'ragged' mutant of Aspergillus amstelodami.

A comparison has been made between mtDNA of the cytoplasmically inherited 'ragged' mutant of Aspergillus amstelodami and that of the wild-type strain. Ragged mitochondria contain both the wild-type mitochondrial genome and several large DNA molecules which are not cleaved by the restriction endonucleases BamHI, HaeIII, HhaI, HindII, HindIII, PstI and MboI, but are converted by either EcoRI or HpaII into a single 820-840 base-pair fragment. Restriction analysis and molecular hybridization data indicate that this fragment contains sequences of wild-type mtDNA located within a 1200-base-pair segment of the 40,500-base-pair genome, for which a basic restriction map has been deduced. It is concluded that in the ragged mutant a small segment of wild-type mtDNA has been amplified as tandem repeats, which is reminiscent of the Rho- petite phenotype of yeast. The results are discussed in relation to the phenomenon of senescence in Podospora anserina.

Aspergillus↗
PubMed1979

Split gene for mitochondrial 24S ribosomal RNA of Neurospora crassa.

The 60 kb circular mitochondrial genome of N. crassa has previously been shown to contain a single transcription unit for 17S and 24S rRNA mapping within the largest Eco RI fragment E1 (19.6 kb). This fragment was isolated from uncloned mitochondrial DNA and further analyzed by cleavage with restriction endonucleases Hind II, Hind III, Bam HI, Pvu II and BgI I, and by electron microscopy of rRNA/DNA hybrids. The resulting map shows a 2.3 kb intervening sequence interrupting the gene for 24S rRNA. The main part (2.7 kb) of this gene is separated from the 17S rRNA gene by a 5 kb segment which contains several transfer RNA genes. This segment is much longer than the putative 1 kb spacer sequence within the 32S precursor molecule for both rRNAs, suggesting a second splicing event in that region.

DNA Restriction Enzymes↗
PubMed1979

Mitochondrial ATPase complex of Aspergillus nidulans and the dicyclohexylcarbodiimide-binding protein.

The dicyclohexylcarbodiimide-binding protein of Aspergillus nidulans has been identified as the smallest subunit of the mitochondrial ATPase complex, and has a molecular weight of approximately 8000. It is extractable from whole mitochondria and from the purified enzyme in neutral chloroform/methanol, contains 30% polar amino acids, and the N-terminal amino acid has been identified as tyrosine. Using a double-labelling technique in the absence and presence of cycloheximide, followed by immunoprecipitation of the enzyme complex with antiserum against Neuospora crassa F1 ATPase, it has been shown that this subunit is synthesized on cytoplasmic ribosomes.

Adenosine Triphosphatases↗
PubMed1979

Mechanism of action of monoketo-organomycin, cystaurimycin and their performic acid-oxidized modifications. I. Effects on bacterial growth and ribosomal peptidyl transferase activity.

The response of 15 bacterial cultures to the inhibitory effects of the above mentioned compounds was investigated. These varied considerably. Escherichia coli cultures resistant to the compounds tested showed that monoketo-organomycin and cystaurimycin inhibit bacterial growth by what appears to be the one and same mechanism which is not the same as that exhibited by their performic acid-oxidized modifications. This was confirmed by using cell free extracts of E. coli. In light of the puromycin reaction, using chloramphenicol and chlorotetracycline as control inhibitors, monoketo-organomycin and cystaurimycin were found to inhibit protein synthesis in vitro by inhibiting peptidyl transferase of ribosomes. In marked contrast, this enzyme was activated, as also was protein synthesis, by their performic acid-oxidized modifications. It was thus suggested that the growth inhibitory effects of the latter compounds might be due to their interference in other metabolic activities of the above test organism. The results obtained are discussed in light of the chemical similarities or differences existing between the compounds investigated.

Acyltransferases↗
PubMed1978

Restriction endonuclease cleavage map of mitochondrial DNA from Aspergillus nidulans.

Mitochondrial DNA of the ascomycete fungus Aspergillus nidulans, a circular molecule of 31 500 base pairs, is cleaved by restriction endonucleases Eco R I, Hind II, Hind III and Bgl II into 3, 7, 9 and 5 fragments, respectively. The relative positions of the cleavage sites could be mapped by analysis of fragments obtained by double enzyme digestions of whole DNA and by complete and partial redigestion of isolated restriction fragments.

Aspergillus nidulans↗
PubMed1977

Intramitochondrial synthesis of membrane proteins in yeast: differential inhibition by ethidium.

Yeast cells (Saccharomyces cerevisiae) were grown in the presence of [14C]phenylalanine and pulse-labelled with [3H]phenylalanine in the presence of cycloheximide. The proteins extractable into chroloform: methanol (2:1) were isolated from mitochondria and analysed by SDS gel filtration. Four protein fractions varying in molecular weight were separated. In order to identify the transcriptional origin and the site of protein synthesis ethidium bromide was used. Different sensitivity of protein syntheses to various concentrations of ethidium was shown. These data are discussed in relation to the possible presence of two classes of membrane-bound polyribosomes in mitochondria.

Cycloheximide↗