Chloroplastic Precursors and their Transport Across the Envelope Membranes

Keegstra, Kenneth; Olsen, Laura J.; Theg, Steven M.

doi:10.1146/annurev.pp.40.060189.002351

Cited by 433 publications

(137 citation statements)

References 53 publications

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“…Indeed, 24 ~o of the first 50 amino acids were serine residues (Fig. 2), which agrees with the observation of Keegstra et al [16] that transit peptides are rich in serine and threonine with these two residues generally constituting 20-35 ~o of the total. …”

Section: Gcc a C A Gtg G T T Ggc A C A C A A "Gag A A T A A T Tat G Tsupporting

confidence: 90%

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Molecular cloning of a cDNA encoding aspartate aminotransferase-P2 from lupin root nodules

Reynolds¹,

Smith²,

Dickson³

et al. 1992

Plant Mol Biol

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Two isoenzymic forms of aspartate aminotransferase are present in the plant fraction of developing lupin root nodules. One of these forms, aspartate aminotransferase-P2 (AAT-P2), increases dramatically with the onset of biological nitrogen fixation and is associated with the assimilation of ammonia by the plant in the Rhizobium-legume symbiosis. A day 18 lupin nodule cDNA library in the lambda ZapII vector was immunoscreened with a monoclonal antibody specific for AAT-P2 and yielded two near-full-length 1700 bp clones. These clones were sequenced. Amino acid sequences from three peptides derived from immunopurified AAT-P2 were aligned, and showed 100% homology with the amino acid sequence deduced from the cDNA clones. The DNA sequence showed 50% homology with AAT sequences from a range of animal sources. Conversion of the clones to the phagemid form allowed their expression in Escherichia coli where both exhibited enzyme activity that could be immunoprecipitated with AAT-P2-specific monoclonal antibodies. Western blot analysis revealed protein moieties with molecular masses of 39, 43, 45 and 55 kDa. The 5' end of the clones coded for a hydrophobic leader sequence of about 50 amino acids indicative of a targeting sequence and consistent with the plastid localisation of nodule AAT-P2.

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Section: Gcc a C A Gtg G T T Ggc A C A C A A "Gag A A T A A T Tat G Tsupporting

confidence: 90%

“…2. Nucleotide and deduced phate carboxylase small subunit transit peptide consensus sequence, as well as transit peptide sequences for pea chloroplast glutamine synthetase and a pea chloroplast heat shock protein [ 16] as shown in Fig. 5.…”

Section: Gcc a C A Gtg G T T Ggc A C A C A A "Gag A A T A A T Tat G Tmentioning

confidence: 99%

Molecular cloning of a cDNA encoding aspartate aminotransferase-P2 from lupin root nodules

Reynolds¹,

Smith²,

Dickson³

et al. 1992

Plant Mol Biol

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“…in hydroxy amino acids, serine and threonine, and small hydrophobic amino acids, alanine and valine, which together are indicative of a transit peptide [ 12]. The site for removal by cleavage of the leader sequence was not determined in the present study (see Discussion).…”

Section: Deduced Amino-acid Sequence For a Precursor To Plastid-locatmentioning

confidence: 54%

The gene and the RNA for the precursor to the plastid-located glycerol-3-phosphate acyltransferase of Arabidopsis thaliana

et al. 1993

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The gene and the RNA from Arabidopsis thaliana for the plastid-located glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) and their encoded product have been studied. The gene (designated ATS1) was isolated by screening a lambda DASH genomic library for cross-hybridization with a radiolabeled probe prepared from cDNA for GPAT from squash. cDNA clones representing the mRNA were isolated by screening a lambda ZAPII cDNA library for hybridization with a radiolabeled probe prepared from a DNA fragment of ATS1. The nucleotide sequences of the gene and the cDNA were determined, and the 5' end of the RNA was mapped by primer extension. Sequences similar to the TATA box, polyadenylation sequences and intron-splicing sequences were found at the expected locations. The pre-mRNA was 3288 nucleotides long and contained 5' and 3'-untranslated sequences of 57 and 442 nucleotides, respectively. The coding sequence of 1377 nucleotides was interrupted by 11 introns of 1412 nucleotides in total and the 3'-untranslated sequence contained another intron of 94 nucleotides. The open-reading frame encoded a polypeptide of 459 amino acid residues, the amino acid sequence of which was highly homologous to those of precursors to plastid-located GPATs from squash and pea. The enzymatic activity of a gene product that was over-produced in Escherichia coli confirmed the identity of the gene.

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“…The envelope, which contains about 1-2~o of the total chloroplast protein, is mainly involved (1) in mediating the exchange of metabolites between the chloroplast and the cytosol [8] (2) in the recognition and import of nuclear-encoded proteins that are destined for the chloroplasts [ 15] and (3) in the biosynthesis of the galactolipid and prenylquinone constituents of the plastids [28]. The envelope is bipartite, consisting of an inner and outer membrane.…”

Section: Introductionmentioning

confidence: 99%

The 24kDa outer envelope membrane protein from spinach chloroplasts: molecular cloning, in vivo expression and import pathway of a protein with unusual properties

et al. 1994

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The 24 kDa outer envelope membrane protein of spinach chloroplasts (omp24) represents a major constituent of this membrane. Sequences of tryptic and endoprotease Glu-C peptides derived from omp24 allowed the design of oligonucleotides which were used to generate a DNA fragment by polymerase chain reaction using spinach cDNA as template. This fragment served as a probe to screen a cDNA library for a full-length clone of the omp24 coding sequence. The protein predicted from the complete sequence only has 148 amino acids and a molecular mass of 16294 Da. It is an acidic protein (calculated isoelectric point 4.8) with a high content of proline residues. Expression of the coding sequence in Escherichia coli and characterization of the purified recombinant protein produced revealed that the overestimation of its molecular mass by SDS-PAGE (ca. 25 kDa) is due to its abnormal amino acid composition. Despite its rather low hydrophobicity (polarity index 49%), omp24 appears to be deeply embedded in the outer membrane. Insertion of omp24 into the membrane proceeds almost independently of surface receptors or targeting sequence but, in contrast to other known outer envelope membrane proteins, is stimulated by ATP.

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Chloroplastic Precursors and their Transport Across the Envelope Membranes

Cited by 433 publications

References 53 publications

Molecular cloning of a cDNA encoding aspartate aminotransferase-P2 from lupin root nodules

Molecular cloning of a cDNA encoding aspartate aminotransferase-P2 from lupin root nodules

The gene and the RNA for the precursor to the plastid-located glycerol-3-phosphate acyltransferase of Arabidopsis thaliana

The 24kDa outer envelope membrane protein from spinach chloroplasts: molecular cloning, in vivo expression and import pathway of a protein with unusual properties

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