Altered Chloroplast Ribosomal Proteins Associated with Erythromycin-Resistant Mutants in Two Genetic Systems of
            <i>Chlamydomonas reinhardi</i>

Mets, Laurens; Bogorad, Lawrence

doi:10.1073/pnas.69.12.3779

Cited by 81 publications

(28 citation statements)

References 24 publications

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“…An altered protein of the 30S subunit has been detected in mutant strains carrying the sm2 gene (Ohta, Inouye, and Sager, in preparation). Further supporting evidence comes from studies in which a non-Mendelian erythromycin resistant strain was shown to contain chloroplast ribosomes with reduced erythromycin binding capacity (10) and with an altered twodimensional gel electrophoretic pattern as compared with wild type (12). In a non-Mendelian spectinomycin resistant strain, chloroplast ribosomes were reported to have lost spectinomycin-binding ability (11), and changes in sedimentation constants have been reported for chloroplast ribosomes from non-Mendelian strains resistant to streptomycin-, spectinomycin, and to neamine (9).…”

Section: Methodsmentioning

confidence: 90%

“…The pattern of subunit localization, mirroring that found in bacterial ribosomes (8) as well as the low levels of cross-resistance between mutants, provide strong, albeit indirect, evidence that each of the mutant genes responsible for resistance codes for a chloroplast ribosomal protein. Several lines of evidence 1715 that non-Mendelian mutations to drug resistance in Chlamydomonas induce alterations in chloroplast ribosomes have been previously reported (7,(9)(10)(11)(12)(13).…”

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confidence: 99%

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Localization of Five Antibiotic Resistances at the Subunit Level in Chloroplast Ribosomes of Chlamydomonas

Schlanger

Sager

1974

Proc. Natl. Acad. Sci. U.S.A.

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The chloroplast ribosomes from five antibiotic resistant strains of Chlamydomonas, each carrying one mutant gene mapping in chloroplast DNA, have been shown to be resistant to the corresponding antibiotic in a poly(U)-directed amino-acid incorporating assay system. The alteration conferring resistance was localized to the 30S subunit in ribosomes from streptomycin, neamine, and spectinomycin resistant strains, and to the 50S subunit in ribosomes from cleocin and carbomycin resistant strains. Spectinomycin resistant ribosomes showed no cross-resistance to any other drugs, but limited crossresistance was noted with the other mutant ribosomes. The similarity between these findings and results reported by others with bacterial ribosomes supports our hypothesis that at least some chloroplast ribosomal proteins are coded by genes in chloroplast DNA.Organelle DNAs with coding potential for many proteins are present in the mitochondria and chloroplasts of all eukaryotic cells (1). In general, chloroplast DNAs with a genomic size of at least 108 daltons (2) may code for several hundred proteins, while the 5-,4m circular mitochondrial DNAs of animal cells mav code for no more than 20 to 30 proteins (3). A well-established function of organelle DNAs is as template for the transcription of organelle ribosomal and transfer RNAs (1); the evidence is accumulating that some proteins associated with organelle function, i.e., photosynthesis and respiration, are determined by organelle genes (4, 5). Are some or all of the organelle ribosomal proteins also coded by the corresponding organelle DNA? This paper presents evidence that 70S chloroplast ribosomes isolated from each of five antibiotic resistant mutant strains of Chlamydomonas are resistant to the corresponding antibiotic, as a result of alterations localized to the level of ribosomal subunits. Mutations conferring resistance to streptomycin (sm2), neamine (nea), spectinomycin (spc), carbomycin (car), and cleocin (cle) each show non-Mendelian inheritance and map in a single linkage group (1, 6, 7). Results to be reported here provide further evidence that this linkage group is located in chloroplast DNA; 70S ribosomes and reassociated subunits from wild-type and five resistant mutant strains each carrying one of these mutant genes were examined for their antibiotic resistance in a poly(U)-directed phenylalanine incorporating system. Resistances to streptomycin, neamine, and spectinomycin were localized to the 30S subunit, and resistances to cleocin and carbomycin to the 50S subunit. The pattern of subunit localization, mirroring that found in bacterial ribosomes (8) as well as the low levels of cross-resistance between mutants, provide strong, albeit indirect, evidence that each of the mutant genes responsible for resistance codes for a chloroplast ribosomal protein. Several lines of evidence 1715 that non-Mendelian mutations to drug resistance in Chlamydomonas induce alterations in chloroplast ribosomes have been previously reported (7, 9-13).

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Section: Methodsmentioning

confidence: 90%

mentioning

confidence: 99%

Localization of Five Antibiotic Resistances at the Subunit Level in Chloroplast Ribosomes of Chlamydomonas

Schlanger

Sager

1974

Proc. Natl. Acad. Sci. U.S.A.

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“…Considering the different patterns of inheritance of our two mutants, it seems that two different proteins of the 30 S subunit are altered, so that nuclear and cytoplasmic gene products are present in the 30 S subunits. Similarly Mets and Bogorad [4] found in the 50 S subunit of a Mendelian and of an uniparental erythromycin-resistant mutant of Chlamydomonas reinhardi different altered ribosomal proteins. Both mutated ribosomal proteins in sr 3 and sr35 cause the same loss of binding capacity for dihydrostreptomycin to the 30 S subunit.…”

Section: Resultsmentioning

confidence: 66%

“…In this connection a comparative study of the ribosomes from organelles and cytoplasm is of great importance. For the investigation of chloroplast ribosomes and chloroplastcytoplasmic interactions the unicellular green alga Chlamydomonas reinhardi is widely used [3], and mutants with altered 70 S ribosomes have been decribed [4,5].…”

Section: Introductionmentioning

confidence: 99%

Binding of dihydrostreptomycin to ribosomes and ribosomal subunits from streptomycin‐resistant mutants of Chlamydomonas reinhardi

Boschetti

Bogdanov

1973

FEBS Letters

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“…Therefore, 0 :4 Chloroplast biogenesis requires cytoplasmically synthesized proteins as well as those of chloroplast origin. Mutant strains of plants (12,23,26) and algae (13,16) deficient in chloroplast ribosomes have proven useful in the study of the interdependence of the chloroplast and nuclear genomes. Among these, the chloroplast ribosome-deficient mutant of Chlamydomonas reinhardtii, ac20crl, has been characterized in some detail (e.g.…”

mentioning

confidence: 99%

Posttranscriptional Regulation of Ribulose 1,5-bisphosphate Carboxylase Small Subunit Accumulation in Chlamydomonas reinhardtii

Mishkind

Schmidt²

1983

Plant Physiol.

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The coordinated synthesis of the subunits of ribulose 1,5-bisphosphate carboxylase was examined by analysis ofthe ch}oroplast ribosome-deficdeat mutant of Chiamydomonas re ardtii, ac2Ocrl. The absence of the chloroplast-synthesized large subunit of this enzyme from cells of this strain is a direct consequence of the lack of chloroplast nbosomes. In contrast, the absence of the cytoplasmicafly-synthesized small subunit of ribuose 1,5-bisphosphate carboxylase from this mutant is not understood. To discern the cause of this absence, we have compared results of in vivo radioactive labeling experiments with those of ceDl-free translations of RNA from ac20crl. Protein products from these experiments were identified by oneand two-dimensional electrophoretic analyses. Neither subunit, revealed either as a stained band or by fluorography ofproteins radioactively labeled in vim for 2 hours, was detected in ac2Ocrl. Cell-free translation of polyadenylated RNA obtained from ac20crl, however, revealed wild-type levels of mRNA for the precursor to the small subunit. This messenger was found to be associated with subribosomal RNP and polysomes. We conclude that the absence of the small subunit of ribulose 1,5-bisphosphate carboxylase from ac2Ocrl is the result of a translational or posttranslational event.in ac20crl at wild-type levels during heterotrophic growth (24), free pools of the cytoplasmically synthesized S of RuBPCase are not detected in these cells (9). Thus, there appears to be a specific interaction between the chloroplast and cytoplasm that serves to regulate the accumulation of S. The experiments in this paper were designed to identify the site(s) at which control of S synthesis is exerted. We demonstrate by in vivo labeling experiments analyzed by two-dimensional pH gradient gel electrophoresis that pools ofpS as well as pools of S itself are not present in detectable levels in ac2Ocrl. We also find that heterotrophically grown cells of ac20crl contain wild-type levels of mRNA for this subunit and that some of this messenger is present on polysomes. Therefore, 0

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Altered Chloroplast Ribosomal Proteins Associated with Erythromycin-Resistant Mutants in Two Genetic Systems of Chlamydomonas reinhardi

Cited by 81 publications

References 24 publications

Localization of Five Antibiotic Resistances at the Subunit Level in Chloroplast Ribosomes of Chlamydomonas

Localization of Five Antibiotic Resistances at the Subunit Level in Chloroplast Ribosomes of Chlamydomonas

Binding of dihydrostreptomycin to ribosomes and ribosomal subunits from streptomycin‐resistant mutants of Chlamydomonas reinhardi

Posttranscriptional Regulation of Ribulose 1,5-bisphosphate Carboxylase Small Subunit Accumulation in Chlamydomonas reinhardtii

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