Search PubMed⌕ Search

Biomedical subjects

M Edelman

Publications and source records attributed to M Edelman.

At least 73 records · Page 4Linked to original sources
PubMed1984

Molecular architecture of the rapidly metabolized 32-kilodalton protein of photosystem II. Indications for COOH-terminal processing of a chloroplast membrane polypeptide.

The molecular architecture of the rapidly metabolized 32-kilodalton chloroplast protein was investigated. Modified proteolytic techniques were applied to construct a cleavage map for this photosynthetic membrane component. The portion which anchors the protein to the membrane was shown to be rich in hydrophobic amino acid residues, while the surface-exposed portion was richer in polar residues. The amino to carboxy polarity of the map was established by comparing oligopeptide radiolabeling data with the polypeptide sequence decoded from the gene. This showed that the anchor domain contains the NH2 terminus, and the exposed domain the COOH terminus. The 32-kilodalton protein was previously demonstrated to derive from a 33.5-kilodalton precursor. We now show that the precursor molecule has a COOH-terminal oligopeptide extension. A model relating precursor cleavage to membrane integration is presented. COOH-terminal processing is proposed to ensure a correct sequence of events for assembly of the 32-kilodalton protein into the photosynthetic membrane.

Amino Acid Sequence↗
PubMed1983

Clone bank of Nicotiana tabacum chloroplast DNA: mapping of the alpha, beta and epsilon subunits of the ATPase coupling factor, the large subunit of ribulosebisphosphate carboxylase, and the 32-kDal membrane protein.

All of the PstI restriction fragments of the chloroplast DNA of Nicotiana tabacum have been cloned in the plasmid vector pBR322. The cloned fragment sizes range from 0.8 to 26 kb, are stable, and can be amplified by chloramphenicol with varying efficiencies. Using these clones we have detailed a PstI physical map of the tobacco chloroplast genome. Selected clones of SalI, BamHI and PstI fragments were used to localize the map positions of the alpha, beta, and epsilon subunits of the chloroplast ATPase coupling factor, the large subunit of ribulosediphosphate carboxylase and the 32-kDal membrane protein. The gene products of these clones were characterized by RNA transcript sizing, immunoprecipitation of maxicell-directed protein synthesis, and hybrid-arrested translation.

Chloroplasts↗
PubMed1982

General occurrence and structural similarity of the rapidly synthesized, 32,000-dalton protein of the chloroplast membrane.

A rapidly metabolized membrane protein from Spirodela, with an apparent molecular weight of 32,000, has been implicated in allosterically regulating electron transport and mediating diuron herbicide sensitivity in the chloroplast (Mattoo, A. K., Pick, U., Hoffman-Falk, H., and Edelman, M. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 1572-1576). Rapid synthesis of a 32,000-dalton plastid membrane protein is demonstrated for several diverse angiosperms and the alga, Chlamydomonas. Comparative partial proteolytic mapping of the polypeptide showed similar patterns for all species tested. In some cases, a 33,500-dalton precursor polypeptide was identified which also displayed interspecific structural homologies. Lastly, in situ analysis of the surface-exposed 32,000-dalton membrane protein yielded a common trypsinization pattern for the organisms studied. These findings point toward a broad distribution and phylogenetic similarity of the 32,000-dalton thylakoid protein of the chloroplast at levels of precursor maturation, membrane orientation, and primary structure.

Chloroplasts↗
PubMed1982

Cytoplasmic hybridization in Nicotiana: mitochondrial DNA analysis in progenies resulting from fusion between protoplasts having different organelle constitutions.

Our previous studies indicated that fusion products with one functional nucleus but organelles of the two fusion partners (i.e. heteroplastomic cybrids) could be obtained by fusing X-irradiated (cytoplasmic donor) with non-irradiated (recipient) Nicotiana protoplasts. The present report deals with the analysis of mitochondria in cybrid populations resulting from the fusion of donor Nicotiana tabacum protoplasts with recipient protoplasts having a N. Sylvestris nucleus but chloroplasts of an alien Nicotiana species, and exhibiting cytoplasmic male sterility. The two fusion parents showed significant differences in restriction patterns of their chloroplast and mitochondrial DNA. Four groups of cybrid plants were obtained by this fusion. All had N. sylvestris nuclei but contained either donor or recipient chloroplasts and had either sterile or fertile anthers. There was no correlation between anther fertility and chloroplast type. The mitochondrial DNA restriction patterns of sterile cybrids were similar to the respective patterns of the sterile fusion partner while the mitochondrial DNA restriction patterns of the fertile cybrids were similar to the respective patterns of the fertile fusion partner. The results indicate an independent assortment of chloroplasts and mitochondria from the heteroplastomic fusion products.

Cell Fusion↗
PubMed1982

Processing of a chloroplast-translated membrane protein in vivo. Analysis of the rapidly synthesized 32 000-dalton shield protein and its precursor in Spirodela oligorrhiza.

The 32 000-dalton (Da) shield protein regulating electron transport in Spirodela oligorrhiza is an integral chloroplast membrane polypeptide. It is rapidly synthesized, constituting a major chloroplast-translation product in vivo. Following in vitro translation of spirodela chloroplast RNA in a wheat germ system, a 33 500-Da polypeptide is produced. Synthesis of a 33 500-Da protein, associated with the chloroplast membrane, is also seen in vivo, within 2 min of pulse-labeling spirodela with radioactive amino acids. Comparative analyses among these polypeptides reveal: (a) all three are deficient in lysine residues; (b) the two 33 500-Da species have indistinguishable partial proteolytic digestion patterns while that for the 32 000-Da protein differs only slightly from them; (c) radioactivity from the 33 500-Da polypeptide is rapidly chased in vivo into the 32 000-Da protein, even in the presence of protein synthesis inhibitors. These results show the 33 500-Da proteins synthesized in vitro and in vivo to be the precursor form of the 32 000-Da shield protein in spirodela, with processing commencing only after completion of the precursor polypeptide chain and insertion into the membrane.

Cell Membrane↗
PubMed1981

Conservation of sequence arrangement among higher plant chloroplast DNAs: molecular cross hybridization among the Solanaceae and between Nicotiana and Spinacia.

Isolated, nick-translated Pvu II fragments of Nicotiana tabacum chloroplast DNA produce specific intra- and intergeneric hybridization signals with chloroplast DNA digests from several representatives of the Solanaceae. These data, along with similarities in restriction enzyme patterns, permit construction of physical maps for Nicotiana line 92 (a cytoplasmic substitution line), Atropa belladonna and Petunia parodii. Plastid-DNA map differences among the Solanaceae are shown to result from single base-pair substitutions as well as local deletions or insertions. Several of these differences of Nicotiana tabacum chloroplast DNA fragments to a chloroplast DNA digest of Spinacia oleracea defines a sequential arrangement of fragments for spinach DNA which is very similar to its published physical map. This is achieved although chloroplast-DNA restriction enzyme patterns from the two organisms are grossly dissimilar. Alignment differences which have been revealed involve the edges of the inverted repeat region where certain single copy stretches in tobacco have been duplicated in spinach.

Base Sequence↗
PubMed1981

The rapidly metabolized 32,000-dalton polypeptide of the chloroplast is the "proteinaceous shield" regulating photosystem II electron transport and mediating diuron herbicide sensitivity.

Mild trypsin treatment of Spirodela oligorrhiza thylakoid membranes leads to partial digestion of the rapidly metabolized, surface-exposed, 32,000-dalton protein. Under these conditions, photoreduction of ferricyanide becomes insensitive to diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], an inhibitor of photosystem II electron transport. Preincubation of thylakoids with diuron leads to a conformational change in the 32,000-dalton protein, modifying its trypsin digestion and preventing expression of diuron insensitivity. Finally, light affects the susceptibility of the 32,000-dalton protein to digestion by trypsin. In other experiments, thylakoids specifically depleted in the 32,000-dalton protein were found to be deficient in electron transport at the reducing side of photosystem II but not at the oxidizing side or in photosystem I activities. Thus, the rapidly metabolized 32,000-dalton thylakoid protein in Spirodela chloroplasts fulfills the requirements of the hypothesized "proteinaceous shield" [Renger, G. (1976) Biochim. Biophys. Acta 440, 287-300] regulating electron flow through photosystem II and mediating diuron sensitivity.

Chloroplasts↗
PubMed1977

[Comparative analysis of conservative and surgical treatment of the imminent myocardial infarct].

It is reported on 108 patients with the symptoms of the impending myocardial infarction, of whom 80 patients were treated conservatively. 51 patients developed a fresh definitive myocardial infarction. 28 patients were surgically treated, 5 of them died. Therefore, in patients with instable angina pectoris the possibility of an early coronary-surgical intervention should be taken into consideration to prevent the development of a definitive myocardial infarction.

Acute Disease↗
PubMed1977

Polyacrylamide gel as a medium for DNA dissociation and reassociation.

Several properties of thermal denaturation and renaturation of DNA in polyacrylamide gels were investigated: (1) Following electrophoresis the DNA band was scanned and shown to increase in absorbance with increasing temperature. The increase was proportioned to DNA concentration across the peak. (2) The dependence of the Tm on salt concentration over a hundred fold range was similar to that found for DNA in free solution. (3) Denaturation of several DNA samples ranging in G + C content from 26 to 71% was compared in gels and free solution. The relationship between Tm and % G + C was virtually identical for both sets of DNAs. (4) The kinetics of DNA renaturation in the gel was followed. Reassociation of bacteriophage T4 DNA was 2nd order and proceeded more rapidly in polyacrylamide gels than in free solution.

Acrylamides↗
PubMed1976

Poly(A)-associated RNA from the mitochondrial fraction of the fungus Trichoderma.

Total RNA was extracted from purified mitochondrial and cytoplasmic fractions of germinating conidia of Trichoderma viride and bound to oligo(dT)-cellulose at 22 and 4 degrees C. Under chromatographic conditions which retained very short poly(A) segments (i.e., 4 degrees C), up to 10% of short-term 32PO4-lebeled RNA from the mitochondrial fraction were selectively bound. The poly(A)-associated RNAs from the mitochondrial and cytoplasmic fractions showed the following characteristics. (a) On polyacrylamide gels mitochondrial fraction RNA had a distinctive pattern with a major peak at about 22 S and a smaller one at about 29 S; in contrast, cytoplasmic fraction RNA was heterogenously distributed along the gel. (b) The poly(A) segment released by RNAase digestion of mitochondrial fraction poly(A)-associated RNA migrated on polyacrylamide gels as molecules 20-25-nucleotides long, while that of the cytoplasmic fraction showed an apparent size of 50-60 nucleotides. (c) Mitochondrial fraction RNA bound to oligo(dT)-cellulose in the cold had a guanine + cytosine content of 21% versus 34% for bulk mitochondrial RNA and 48% for cytoplasmic poly(A)-associated RNA; the oligo(dT)-bound RNAs were further identified by their high percentages of adenine residues (46% for the mitochondria and 30% for the cytoplasm). (d) The poly(A)-associated RNA fraction was translated, in vitro, in a cell-free protein-synthesizing system from wheat germ. The products induced by cytoplasmic RNA showed a complex pattern on polyacrylamide gels of many polypeptides ranging in molecular weights from 10000 to 40000. The pattern induced by mitochondrial fraction RNA however, was much simpler, revealing two discrete, main products: a major one at Mr approximately 13000 and a minor one at Mr approximately 20000.

Chromatography, Affinity↗
PubMed1976

Large subunit ribulosebisphosphate carboxylase messenger RNA from Euglena chloroplasts.

RNA from wild-type Euglena, aplastidic mutant cells, and purified chloroplasts was chromatographed on oligo(dT)-cellulose at 4 degrees. The poly(A)-containing and poly(A)-lacking fractions from each were then tested in a cell-free protein-synthesizing system from wheat germ for their abilities to specifically stimulate synthesis of large subunit ribulosebisphosphate carboxylase [EC 4.1.1.39; 3-phospho-D-glycerate carboxy-lyase (dimerizing)]. The large subunit polypeptide (59,000 molecular weight) was identified in the in vitro reaction by two-dimensional electrophoresis involving isoelectric focusing and size filtration on polyacrylamide gels. Template activity for the large subunit was detected in wild-type cells but not in aplastidic mutant strains; it was highly enriched in the isolated chloroplasts. This messenger was present only in the poly(A)-lacking RNA fraction, where it constituted the most prominent template species of chloroplast RNA. The large subunit message was freed of considerable non-messenger RNA contamination and localized to the 10-20S fraction by sucrose gradient centrifugation.

Carboxy-Lyases↗