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R Mache

Publications and source records attributed to R Mache.

At least 37 records · Page 2Linked to original sources
PubMed1994

S1F binding site is related to but different from the light-responsive GT-1 binding site and differentially represses the spinach rps1 promoter in transgenic tobacco.

Nuclear genes encoding plastid ribosomal proteins are more highly expressed in leaves than in roots. This leaf-specific induction seems to be light-independent. We have previously characterized a spinach nuclear factor S1F binding to a cis-element within the rps1 promoter, which negatively regulates both the rps1 and the cauliflower mosaic virus 35S promoters in transient expression assays. Here, we show that the S1F binding site is related to but different from the light-responsive Box II of the pea rbcS-3A promoter, which is recognized by the nuclear factor GT-1. Transgenic plant analyses showed that the S1F site tissue-specifically represses the rps1 promoter in roots as well as in etiolated seedlings. We suggest that the GT-1-related S1F binding site is responsible, at least in part, for the transcriptional repression of rps1 in nonphotosynthetic tissues such as roots.

Base Sequence↗
PubMed1993

Erythromycin and 5S rRNA binding properties of the spinach chloroplast ribosomal protein CL22.

The spinach chloroplast ribosomal protein (r-protein) CL22 contains a central region homologous to the Escherichia coli r-protein L22 plus long N- and C-terminal extensions. We show in this study that the CL22 combines two properties which in E. coli ribosome are split between two separate proteins. The CL22 which binds to the 5S rRNA can also be linked to an erythromycin derivative added to the 50S ribosomal subunit. This latter property is similar to that of the E. coli L22 and suggests a similar localization in the 50S subunit. We have overproduced the r-protein CL22 and deleted forms of this protein in E. coli. We show that the overproduced CL22 binds to the chloroplast 5S rRNA and that the deleted protein containing the N- and C-terminal extensions only has lost the 5S rRNA binding property. We suggest that the central homologous regions of the CL22 contains the RNA binding domain.

Chloroplasts↗
PubMed1993

Characterization of a multigene family encoding an exopolygalacturonase in maize.

Genes coding for exopolygalacturonase in plants are abundantly expressed during the development of the male gametophyte (pollen). We have analysed genomic and cDNA clones for several representatives of the small multigene family encoding exopolygalacturonase from Zea mays. Structures for both actively transcribed genes and non-transcribed pseudogenes are reported. Comparisons of the nucleotide sequences for coding and flanking regions of different members of the gene family reveal surprisingly few base substitutions, suggesting that the exopolygalacturonase gene family of maize arose through very recent multiple duplication events. The pseudogenes are shown to possess an 80 bp insertion within the coding region, which may represent a relictual intron that has been lost in the active genes. We estimate that 12 exopolygalacturonase genes exist in maize. None appear to be expressed at a detectable level in tissue other than those associated with pollen development.

Base Sequence↗
PubMed1993

The six genes of the Rubisco small subunit multigene family from Mesembryanthemum crystallinum, a facultative CAM plant.

The nucleotide sequences of the entire gene family, comprising six genes, that encodes the Rubisco small subunit (rbcS) multigene family in Mesembryanthemum crystallinum (common ice plant), were determined. Five of the genes are arranged in a tandem array spanning 20 kb, while the sixth gene is not closely linked to this array. The mature small subunit coding regions are highly conserved and encode four distinct polypeptides of equal lengths with up to five amino acid differences distinguishing individual genes. The transit peptide coding regions are more divergent in both amino acid sequence and length, encoding five distinct peptide sequences that range from 55 to 61 amino acids in length. Each of the genes has two introns located at conserved sites within the mature peptide-coding regions. The first introns are diverse in sequence and length ranging from 122 bp to 1092 bp. Five of the six second introns are highly conserved in sequence and length. Two genes, rbcS-4 and rbcS-5, are identical at the nucleotide level starting from 121 bp upstream of the ATG initiation codon to 9 bp downstream of the stop codon including the sequences of both introns, indicating recent gene duplication and/or gene conversion. Functionally important regulatory elements identified in rbcS promoters of other species are absent from the upstream regions of all but one of the ice plant rbcS genes. Relative expression levels were determined for the rbcS genes and indicate that they are differentially expressed in leaves.

Adaptation, Biological↗
PubMed1993

The ubiquitous presence of exopolygalacturonase in maize suggests a fundamental cellular function for this enzyme.

Exopolygalacturonase (exoPG) is a pectin-degrading enzyme abundant in maize pollen. Using immunochemistry and in situ hybridization it is shown that in addition to its presence in pollen, exoPG is also present in sporophytic tissues, such as the tapetum and mesophyll cells. The enzyme is located in the cytoplasm of pollen and of some mesophyll cells. In other mesophyll cells, the tapetum and the pollen tube, exoPG is located in the cell wall. The measurement of enzyme activity shows that exoPG is ubiquitous in the vegetative organs. These results suggest a general function for exoPG in cell wall edification or degradation. ExoPG is encoded by a closely related multigene family. The regulation of the expression of one of the exoPG genes was analyzed in transgenic tobacco. Reporter GUS activity was detected in anthers, seeds and stems but not in leaves or roots of transgenic plants. This strongly suggests that the ubiquitous presence of exoPG in maize is the result of the expression of different exoPG genes.

Base Sequence↗
PubMed1993

Structure and expression of the nuclear gene coding for the chloroplast ribosomal protein L21: developmental regulation of a housekeeping gene by alternative promoters.

We have cloned and sequenced the nuclear gene of the chloroplast ribosomal protein L21 (rpl21) of Spinacia oleracea. The gene consists of five exons and four introns. All introns are located in the sequence which corresponds to the Escherichia coli-like central core of the protein. L21 mRNA is present in photosynthetic (leaves) and nonphotosynthetic (roots and seeds) plant organs, although large quantitative differences exist. Primer extension and S1 nuclease mapping experiments revealed the existence of two types of transcripts in leaves. The two corresponding start sites were defined as P1 and P2. In roots and seeds, we found only the shorter of the two transcripts (initiated at P2). The nucleotide sequence surrounding P2 resembles promoters for housekeeping and vertebrate r-protein genes. Analysis of several promoter constructions by transient expression confirmed that both transcripts originate from transcription initiation. Results are interpreted to mean that the expression of the rpl21 gene is regulated by alternative promoters. One of the promoters (P2) is constitutive, and the other one (P1) is specifically induced in leaves, i.e., its activation should be related to the transformation of amyloplasts or proplastids to chloroplasts. The gene thus represents the first example of a housekeeping gene which is regulated by the organ-specific usage of alternative promoters. Primer extension analysis and S1 nuclease mapping of another nucleus-encoded chloroplast ribosomal protein gene (rps1) give evidence that the same type of regulation by two-promoter usage might be a more general phenomenon of plant chloroplast-related ribosomal protein genes. Preliminary results indicate that presence of conserved sequences within the rpl21 and rps1 promoter regions which compete for the same DNA binding activities.

Amino Acid Sequence↗
PubMed1992

Sequence-specific interaction between S1F, a spinach nuclear factor, and a negative cis-element conserved in plastid-related genes.

The nuclear gene rps1 coding for the spinach plastid ribosomal protein CS1 exhibits both a constitutive and leaf-specific expression pattern. In contrast to other chloroplast-related genes like rbcS and cab, the leaf induction of rps1 expression is light-independent. These unique features of rps1 expression provide good models to study the mechanisms regulating plastid development and differentiation in higher plants. We report on the identification of a spinach leaf nuclear factor, designated S1F, interacting with the rps1 promoter. The S1F binding site is conserved in the promoter region of many plastid-related genes, including rbcS, cab, and rpl21. A binding activity similar to S1F was detected in nuclear extract from dark-grown de-differentiated soybean suspension cells. Through site-specific mutagenesis and transient expression in soybean cell protoplasts, we show that the S1F binding site is a negative element down-regulating the promoter activity of rps1. A ligated tetramer of S1F site was able to repress activity of the cauliflower mosaic virus 35 S promoter extending the negative function of the S1F binding site on promoter activity.

Base Sequence↗
PubMed1992

Characterization and RNA-binding properties of a chloroplast S1-like ribosomal protein.

Control of translation is an important step in chloroplast gene expression. A first control can be exerted during the initiation complex formation which, in Escherichia coli, involves the ribosomal protein (r-protein) S1. A cDNA clone have been characterized which codes for the precursor of the chloroplast r-protein CS1. The mature protein consists of a central core which shows 31.5% amino acid homology to the E. coli protein S1. The CS1 is considerably shorter (40 kDa) than the protein S1 (61 kDa). The core fragment contains three degenerated repeats which show homology to both the ribosome- and the RNA-binding domain of S1. RNA-protein CS1 interactions were studied by UV cross-linking and toe-printing. CS1 has been over-expressed in E. coli, and after purification its RNA-binding properties were studied in vitro. We conclude that the CS1 exhibits an RNA-binding activity which is actively involved in the chloroplast initiation complex formation. It is shown that the CS1 binds to poly(A) in contrast with S1 which binds strongly to poly(U). These results are interpreted in relation to the presence of poly(A)-rich regions in chloroplast transcripts of higher plants.

Amino Acid Sequence↗
PubMed1992

Structure and expression of the nuclear gene coding for the plastid CS1 ribosomal protein from spinach.

The chloroplast ribosomal protein CS1 is an essential component of the plastids translational machinery involved in translation initiation. Southern analysis suggests that the corresponding nuclear gene is present in one copy in the spinach genome. We have isolated and sequenced the gene (rps1) to study its expression at the transcriptional level. The gene consists of 7 exons and 6 introns including an unusually large intron in the 5' coding region. No canonical TATA-box is found in the 5' upstream region of the gene. rps1 transcripts are detected early during germination and a significant accumulation is observed after the protrusion of the radicle. CS1 mRNAs are present in all organs of young seedlings although there are dramatic differences in the steady state level of the mRNAs between leaves and roots tissues. Transcripts accumulate independently of the presence or absence of light. Band shift analysis shows that the +1, -400 bp region of the gene can bind different sets of proteins isolated from roots and leaves nuclei. We suggest that the expression of the housekeeping plastid-related rps1 gene is regulated in a tissue-specific manner by transcriptional trans-acting factors.

Amino Acid Sequence↗
PubMed1992

Organization and expression of the nuclear gene coding for the plastid-specific S22 ribosomal protein from spinach.

We report here on the genomic organization and expression of a nuclear gene coding for a plastid ribosomal protein. The gene encodes the plastid-specific ribosomal protein S22 (formerly named CS-S5). Southern blot analysis suggests that the gene is present in one copy in the spinach genome. The gene consists of 5 exons of sizes ranging from 108 to 273 bp and of 4 introns of 1410, 92, 386 and 82 bp. The exon-intron splice junctions and intron branch sites fit well the consensus sequences for plant introns. The major transcription start site has been determined 29 bp upstream of the AUG initiation codon by primer extension and S1 nuclease mapping. No canonical TATA box is found but some other possible promoter motifs are observed. Transcripts are detected in leaves, etiolated leaves, roots and seeds suggesting that the rps22 gene is expressed constitutively. During germination a marked increase in the relative steady-state level of the mRNA can be seen as soon as 24 h after imbibition of the seeds.

Amino Acid Sequence↗
PubMed1991

Conservation and evolution of the nucleus-encoded and chloroplast-specific ribosomal proteins in pea and spinach.

Two cDNA clones have been isolated from a lambda g11 cDNA library constructed with poly(A)+ mRNAs prepared from spinach seedlings. These nuclear cDNAs encode chloroplast (cp) ribosomal (r) proteins designated L24 and L40. These r-proteins have been identified in the cp 50S r-subunit by immunoblot analysis, amino acid (aa) composition and N-terminal aa sequencing. The L24 r-protein contains a central eubacterial homologous core with the N- and C-terminal polypeptide extensions. The L40 r-protein has no homologous counterpart in bacterial ribosomes. The two nuclear encoded r-proteins have their homologues in pea, a legume, showing that specific elements of cp ribosomes are conserved in higher plants. Surprisingly, the cp-specific r-protein L40 has a higher aa substitution rate than that of other eubacterial-like cp r-proteins identified previously in pea and spinach.

Amino Acid Sequence↗
PubMed1991

Characterization of a protein binding sequence in the promoter region of the 16S rRNA gene of the spinach chloroplast genome.

By means of mobility-shift assays and Exonuclease III mapping we have determined a 14 bp sequence (named CDF2 binding site) located in front of the 16S rRNA initiation start site which is protected by a spinach chloroplast extract. This region does not include neither one of the two '-35' nor of the two '-10' E. coli-like promoter elements which are recognised by E. coli RNA polymerase in vitro. The CDF2 binding site is specifically recognized by two small polypeptides which migrate corresponding to 35 and 33 kDa respectively as shown by UV cross-linking experiments. In vivo transcription initiation of the 16S rRNA gene occurs 13 nucleotides downstream of the 14 bp sequence and is different from the transcription start site which is used by E.coli polymerase in vitro.

Base Sequence↗
PubMed1991

Characterization of pollen polygalacturonase encoded by several cDNA clones in maize.

A full-length cDNA clone, named PG1, abundantly expressed in late stages of pollen development, has been isolated from a cDNA library using a differential screening method with cDNA probes representative of microspores at early or late developmental stages. The encoded 410 amino acid polypeptide has significant homology with various polygalacturonases (PG) described elsewhere. Two polypeptides, of 49 and 53 kDa respectively, have been identified in the active PG fraction, isolated from mature pollen by immuno-cross-reaction with tomato PG antibodies. According to their N-terminal sequence, they can be identified as being mature peptides encoded by the PG1 cDNA clone. We propose that these two proteins derive from a unique precursor through several post-translational events, including the excision of a 22 amino-terminal signal peptide and glycosylation. PG-encoding genes from a small genomic family. Sequence analysis of three PG cDNA clones shows that they are closely related. The divergence of nucleotides between these three cDNA clones is 1%. They encode the same product.

Amino Acid Sequence↗
PubMed1991

Nucleotide sequence and expression of a novel glycine-rich protein gene from Arabidopsis thaliana.

A clone containing a gene coding for a novel glycine-rich protein has been identified in an Arabidopsis thaliana genomic library. The gene codes for a 339 amino acid protein and is interrupted by a 686 bp intervening sequence. The gene is present in one copy only. Transcripts accumulate mainly in hypocotyls and stems and the highest level is observed in rosettes before the start of stem elongation. The protein contains 71% of glycine residues and is highly hydrophobic.

Amino Acid Sequence↗
PubMed1990

Evidence for a composite phylogenetic origin of the plastid genome of the brown alga Pylaiella littoralis (L.) Kjellm.

The nucleotide sequence and the 5' flanking region of the rbcL gene coding for the large subunit of ribulose bisphosphate-1,5-carboxylase/oxygenase of Pylaiella littoralis, a brown alga, has been determined and the deduced amino-acid sequence has been compared to those of various photosynthetic and chemoautotrophic Eubacteria, of a red alga and of green plastids (Euglena gracilis, green algae and higher plants). Unlike the rbcL genes of green plastids which are more closely related to those of cyanobacteria, the P. littoralis rbcL gene is more closely related to that of a beta-purple bacterium, as was found for the rbcS gene of another chromophytic alga [Boczar et al., Proc Natl Acad Sci USA 86: 4996-4999, 1989]. Matrix data of homology between the rbcL gene of P. littoralis and the same gene of other organisms are presented. Based on our previous report, the gene coding for the 16S rRNA from P. littoralis is closely related to that of E. gracilis (Markowicz et al., Curr Genet 14: 599-608, 1988). We suggest that the large plastid DNA molecule of P. littoralis is a phylogenetically composite genome which probably resulted from mixed endosymbiosis events, or from a horizontal transfer of DNA.

Amino Acid Sequence↗
PubMed1990

Hypothesis for the evolutionary origin of the chloroplast ribosomal protein L21 of spinach.

A full size cDNA clone encoding the chloroplast ribosomal protein L21 from spinach is presented. The identity of the clone and the location of the transit peptide processing site were determined by comparison with the N-terminal amino acid sequence of the spinach chloroplast protein CS-L7 previously identified. L21 r-protein sequences from spinach, Marchantia polymorpha and Escherichia coli are compared. Quite surprisingly, the data do not suggest that the rpl21 nuclear gene from spinach was derived through intracellular gene transfer from the chloroplast genome. The possibility of a mitochondrial origin for rpl21 gene of spinach is discussed.

Amino Acid Sequence↗