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K Zetsche

Publications and source records attributed to K Zetsche.

At least 19 recordsLinked to original sources
PubMed1998

The mitochondrial genome of Chlorogonium elongatum inferred from the complete sequence.

The 22,704-bp circular mitochondrial DNA (mtDNA) of the chlamydomonad alga Chlorogonium elongatum was completely cloned and sequenced. The genome encodes seven proteins of the respiratory electron transport chain, subunit 1 of the cytochrome oxidase complex (cox1), apocytochrome b (cob), five subunits of the NADH dehydrogenase complex (nad1, nad2, nad4, nad5, and nad6), a set of three tRNAs (Q, W, M), and the large (LSU)- and small (SSU)-subunit ribosomal RNAs. Six group-I introns were found, two each in the cox1, cob, and nad5 genes. In each intron an open reading frame (ORF) related to maturases or endonucleases was identified. Both the LSU and the SSU rRNA genes are split into fragments intermingled with each other and with other genes. Although the average A + T content is 62.2%, GC-rich clusters were detected in intergenic regions, in variable domains of the rRNA genes, and in introns and intron-encoded ORFs. A comparison of the genome maps reveals that C. elongatum and Chlamydomonas eugametos mtDNAs are more closely related to one another than either is to Chlamydomonas reinhardtii mtDNA.

Apoproteins↗
PubMed1997

Origin and evolution of mitochondria: what have we learnt from red algae?

The purpose of this review is to present an account of our current understanding of the structure, organization and evolution of mitochondrial genomes, and to discuss the origin and evolution of mitochondria from the perspective recently provided by the extensive sequencing of various mitochondrial genomes. Mitochondrial-en-coded protein phylogenies are congruent with nuclear phylogenies and strongly support a monophyletic origin of mitochondria. The newly available data from red-algal mitochondrial genomes, in particular, show that the structural and functional diversity of mitochondrial genomes can be accounted for by paralogous evolution. We also discuss the influence of other constraints, such as uniparental inheritance, on the evolution of genome organization in mitochondria.

DNA, Circular↗
PubMed1997

The apocytochrome-b gene in Chlorogonium elongatum (Chlamydomonadaceae): an intronic GIY-YIG ORF in green algal mitochondria.

The mitochondrial cob gene from the green alga Chlorogonium elongatum (Chlamydomonadaceae) is interrupted by two group-I introns each containing an open reading frame in-phase with the upstream exon. One of these ORFs belongs to the LAGLI-DADG family, the other to the GIY-YIG family. The latter has not yet been identified in any mitochondrial genome except those from fungi. The Chlorogonium ORFs are similar to ORFs encoded by fungal introns that are located at an identical position within the gene, and to the ORF encoded by the mobile intron in the Chlamydomonas smithii cob gene.

Amino Acid Sequence↗
PubMed1996

The CMS-associated 16 kDa protein encoded by orfH522 in the PET1 cytoplasm is also present in other male-sterile cytoplasms of sunflower.

In sunflower plants carrying the PET1 cytoplasm male sterility (CMS) is associated with a new open reading frame (orfH522) in the 3'-flanking region of the atpA gene and an additional 16 kDa protein. Twenty-seven male-sterile cytoplasms of different origin were studied for the expression of the 16 kDa protein. In addition to the PET1 cytoplasm nine other male-sterile cytoplasms express the CMS-associated protein. These CMS sources originate from different interspecific crosses, from spontaneously occurring male-sterile plants in wild sunflower and from induced mutagenesis. Polyclonal antisera were raised against fusion proteins which contain 421 bp of the 3'-coding region of orfH522 to verify by immunological methods the identity of the other CMS cytoplasms. The anti-ORFH522 antiserum showed a positive reaction in the immunoblot with all CMS cytoplasms which expressing the 16 kDa protein. Investigations of the mitochondrial DNA demonstrated that all ten CMS cytoplasms which express the 16 kDa protein have the same organization at the atpA locus. OrfH522 as probes gave the same transcript pattern for the investigated CMS cytoplasms, just as for PET1. The MAX1 cytoplasm has an orfH522-related sequence but does not synthesize the 16 kDa protein. Using the sodium carbonate treatment the 16 kDa protein proved to be membrane-bound. Computer analyses predict that the hydrophobic N-terminal region of ORFH522 may form a transmembrane helix functioning as membrane anchor.

Cytoplasm↗
PubMed1995

Physical map and gene organization of the mitochondrial genome from the unicellular green alga Platymonas (Tetraselmis) subcordiformis (Prasinophyceae).

The entire mitochondrial genome (mt genome) of the unicellular green alga Platymonas subcordiformis (synonym Tetraselmis subcordiformis; Prasinophyceae) was cloned and a physical map for the four restriction enzymes Hind III, Eco RI, Bg/II and Xba I was constructed. The mt genome of P. subcordiformis is a 42.8 kb circular molecule, coding for at least 23 genes. Hybridization and sequence analysis revealed the presence of a ca. 1.5 kb inverted repeat on the mt genome of P. subcordiformis. Phylogenetic analyses based on sequences of several coxI genes were carried out. Our data indicate that mitochondria from P. subcordiformis and from land plants form a natural, monophyletic group.

Chlorophyta↗
PubMed1994

Functional loss of all ndh genes in an otherwise relatively unaltered plastid genome of the holoparasitic flowering plant Cuscuta reflexa.

We have cloned and sequenced an area of about 9.0 kb of the plastid DNA (ptDNA) from the holoparasitic flowering plant Cuscuta reflexa to investigate the evolutionary response of plastid genes to a reduced selective pressure. The region contains genes for the 16S rRNA, a subunit of a plastid NAD(P)H dehydrogenase (ndhB), three transfer RNAs (trnA, trnI, trnV) as well as the gene coding for the ribosomal protein S7 (rps7). While the other genes are strongly conserved in C. reflexa, the ndhB gene is a pseudogene due to many frameshift mutations. In addition we used heterologous gene probes to identify the other ndh genes encoded by the plastid genome in higher plants. No hybridization signals could be obtained, suggesting that these genes are either lost or strongly altered in the ptDNA of C. reflexa. Together with evidence of deleted genes in the ptDNA of C. reflexa, the plastid genome can be grouped into four classes reflecting a different evolutionary rate in each case. The phylogenetic position of Cuscuta and the significance of ndh genes in the plastid genome of higher plants are discussed.

Base Sequence↗
PubMed1993

Organization of plastid-encoded ATPase genes and flanking regions including homologues of infB and tsf in the thermophilic red alga Galdieria sulphuraria.

We have cloned and sequenced the plastid ATPase operons (atp1 and atp2) and flanking regions from the unicellular red alga Galdieria sulphuraria (Cyanidium caldarium). Six genes (5 atpI, H, G, F, D and A 3) are linked in atp1 encoding ATPase subunits a, c, b, b, delta and alpha, respectively. The atpF gene does not contain an intron and overlaps atpD by 1 bp. As in the genome of chloroplasts from land plants, the cluster is located downstream of rps2, but between this gene and atp1 we found the gene for the prokaryotic translation elongation factor TS. Downstream of atpA, we detected two open reading frames, one encoding a putative transport protein. The genes atpB and atpE, encoding ATPase subunits beta and epsilon, respectively, are linked in atp2, separated by a 2 bp spacer. Upstream of atpB, an uninterrupted orf167 was detected which is homologous to an intron-containing open reading frame in land plant chloroplasts. This orf167 is preceded on the opposite DNA strand by a homologue to initiation factor 2 in prokaryotes. The arrangement of atp1 and atp2 is the same as observed in the multicellular red alga Antithamnion sp., indicating a conserved genome arrangement in the red algal plastid genome. Differences compared to green chloroplast genomes suggest a large phylogenetic distance between red algae and green plants, while similarities in arrangement and sequence to chromophytic ATPase operons support a red algal origin of chlorophyll a/c-containing plastids or alternatively point to a common prokaryotic endosymbiont.

Adenosine Triphosphatases↗
PubMed1993

Glutamate synthase is plastid-encoded in a red alga: implications for the evolution of glutamate synthases.

An actively transcribed gene (glsF) encoding for ferredoxin-dependent glutamate synthase (Fd-GOGAT) was found on the plastid genome of the multicellular red alga Antithamnion sp. Fd-GOGAT is not plastid-encoded in chlorophytic plants, demonstrating that red algal plastid genomes encode for additional functions when compared to those known from green chloroplasts. Moreover, our results suggest that the plant Fd-GOGAT has an endosymbiotic origin. The same may not be true for NADPH-dependent GOGAT. In Antithamnion glsF is flanked upstream by cpcBA and downstream by psaC and is transcribed monocistronically. Implications of these results for the evolution of GOGAT enzymes and the plastid genome are discussed.

Amino Acid Sequence↗
PubMed1992

Large ATP synthase operon of the red alga Antithamnion sp. resembles the corresponding operon in cyanobacteria.

The large plastid ATP synthase operon of the multicellular red alga Antithamnion sp. was cloned and the sequence of six ATPase genes determined. The operon resembles more the one from cyanobacteria than the ATP synthase operon of the chloroplast genome. The gene order is atpI, H, G, F, D and A, coding for the ATPase subunits a, c, b', b, delta and alpha, respectively. In green plants, the genes atpG and atpD are located in the nucleus. Unlike the situation in three published cyanobacterial ATP synthase operons, atpC, coding for the gamma subunit, is not a part of the rhodoplast operon. A single 4.5 kb transcript was detected with atpG, F, D and A gene probes that could span the whole operon, but no transcript could be detected with atpI and atpH probes. The end of an open reading frame preceding the atp genes shows remarkable homology to elongation factor TS from Escherichia coli. Behind the ATPase cluster, two open reading frames were detected that are not homologous to any known chloroplast gene. One of them may code for a transport protein of unknown specificity. Gene arrangement and sequence comparisons support the hypothesis of a polyphyletic origin of rhodoplasts and chloroplasts.

Amino Acid Sequence↗
PubMed1992

Organization and expression of a phycobiliprotein gene cluster from the unicellular red alga Cyanidium caldarium.

We have sequenced a plastid gene cluster from the unicellular red alga Cyanidium caldarium which is located downstream from the psbA gene and contains, in the following order, genes for a beta-allophycocyanin-like protein (apcB'), a putative 9.5 kDa allophycocyanin linker protein (apcL9.5) and a putative 29 kDa phycocyanin linker protein (cpcL29). The apcB' and apcL9.5 genes are organized in the form of an operon. The cpcL29 gene is transcribed monocistronically from the opposite strand of DNA. Both transcription units are probably terminated at a 25 bp inverted repeat 3 and 5 bp downstream of the stop codons of the apcL9.5 and cpcL29 genes, respectively. The levels of both transcripts are greatly reduced in the dark as is the psbA transcript. Downstream from the phycobiliprotein gene cluster two open reading frames (ORFs) were found which are homologous to ORFs from plastid DNAs and cyanelle DNA of Cyanophora paradoxa. Sequence homologies between genes analysed in this study and corresponding genes from cyanobacteria, chlorophytic plastids and cyanelles point to a large phylogenetic distance between the plastids of Cyanidium and cyanobacteria and other plastid types.

Amino Acid Sequence↗
PubMed1992

A 16 kb small single-copy region separates the plastid DNA inverted repeat of the unicellular red alga Cyanidium caldarium: physical mapping of the IR-flanking regions and nucleotide sequences of the psbD-psbC, rps16, 5S rRNA and rpl21 genes.

The four inverted repeat (IR) flanking regions of the Cyanidium caldarium plastid DNA were cloned. Southern blotting, transcript and sequence analyses of the border regions revealed the psbD-psbC operon and the rps16 gene within the large single-copy region upstream of the 16S rDNA gene and the rpl21 gene downstream of the 5S rDNA within the 16 kb small single-copy region. The size of the IR is ca. 5 kb. The nucleotide sequences of the psbD-psbC, rps16, rpl21 and 5S rRNA genes with the corresponding alignments and physical maps of the regions are presented. Northern analysis revealed a less complex psbD-psbC transcription pattern than has been found in higher plants. Comparisons to other red algal data point to structural diversity within red algal plastid DNA.

Amino Acid Sequence↗
PubMed1992

Organization and sequence of photosynthetic genes from the plastid genome of the holoparasitic flowering plant Cuscuta reflexa.

We have cloned and sequenced an area of about 6 kb of the plastid DNA (ptDNA) from the holoparasitic plant Cuscuta reflexa. This region contains (in the following order) genes for the cytochrome b6 f-complex subunit V (petG), tRNA(Val) (trnV), tRNA(Met) (trnM), the epsilon- and beta-subunit of the chloroplast ATP-synthase (atpE and atpB) and the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco; rbcL). In addition we identified other photosynthesis-related genes (atpA, petB, psaA, psbA, psbB, psbC, and psbD) in C. reflexa by heterologous hybridization. The gene arrangement of the sequenced area is, except for the petG gene, the same as in ptDNAs of other higher plants (e.g. Nicotiana tabacum). Sequence homologies between the Cuscuta genes and corresponding genes from higher plants are in the range of 90%. The only significant difference is that the rbcL gene of C. reflexa encodes a polypeptide which is 18-23 amino acids longer than in other higher plants. This is remarkable since C. reflexa has lost its ability to grow photoautotrophically. The transcript level of the rbcL gene, however, is strongly reduced as compared to tobacco. These findings are compatible with results from Western blotting analysis, where no Rubisco large subunit was detectable, and with the lack of Rubisco activity in crude extracts of C. reflexa.

Amino Acid Sequence↗
PubMed1992

Structure and expression of a plastid-encoded groEL homologous heat-shock gene in a thermophilic unicellular red alga.

A gene homologous to the E. coli groEL locus was identified on the plastid genome of the unicellular red alga Cyanidium caldarium strain 14-1-1 (synonym: Galdieria sulphuraria). The complete nucleotide sequence was determined and compared to bacterial- and nuclear-encoded counterparts of higher plants. At the amino-acid level the C. caldarium gene shows 70% homology to the corresponding gene of the cyanobacterium Synechococcus and 52% homology to nuclear-encoded counterparts of higher plants, respectively. Northern and Western blot experiments were used to investigate the dependence of the transcript- and protein-level on culture temperature and heat shock.

Amino Acid Sequence↗
PubMed1991

Structural features of the plastid ribosomal RNA operons of two red algae: Antithamnion sp. and Cyanidium caldarium.

The nucleotide sequences of the plastid 16S rDNA of the multicellular red alga Antithamnion sp. and the 16S rDNA/23S rDNA intergenic spacers of the plastid DNAs of the unicellular red alga Cyanidium caldarium and of Antithamnion sp. were determined. Sequence comparisons support the idea of a polyphyletic origin of the red algal and the higher-plant chloroplasts. Both spacer regions include the unsplit tRNA(Ile)(GAU) and tRNA(Ala)(UGC) genes and so the plastids of both algae form a homogeneous group with those of chromophytic algae and Cyanophora paradoxa characterized by 'small-sized' rDNA spacers in contrast to green algae and higher plants. Nevertheless, remarkable sequence differences within the rRNA and the tRNA genes give the plastids of Cyanidium caldarium a rather isolated position.

Base Sequence↗
PubMed1991

A mitochondrial 16 kDa protein is associated with cytoplasmic male sterility in sunflower.

Cytoplasmic male-sterile lines CMS89 and CMSBaso of sunflower (Helianthus annuus) differ from the fertile lines HA89 and Baso in a mitochondrial DNA sequence in the vicinity of the atpA gene. In addition, the transcriptional pattern of the atpA gene is changed in male-sterile lines compared to fertile ones. Besides one main transcript in the fertile lines, the male-sterile lines additionally show larger transcripts. Investigation of Baso and CMSBaso revealed that the two fertility-restored lines of CMS89 have the same transcripts as CMSBaso or a combination of CMSBaso and CMS89. Comparing the mitochondrial in organello translation products we observed a unique 16 kDa protein, which is expressed in male-sterile lines carrying the H. petiolaris cytoplasm but is not detectable in fertile lines with H. annuus cytoplasm. The 16 kDa protein can also be observed in restored lines but not in H. petiolaris. As the expression of the 16 kDa polypeptide seems to be linked to the interspecific cross between H. petiolaris and H. annuus it may play a role in CMS. By different criteria such as molecular mass, isoelectric point and peptide fingerprinting the alpha subunit of the F1-ATPase of male-sterile and fertile lines is very similar if not identical.

Crosses, Genetic↗