Light-stimulated synthesis of aminoacyl-tRNA synthetases in greening Euglena gracilis

Parthier, B.; Krauspe, R.; Samtleben, S.

doi:10.1016/0005-2787(72)90415-7

Cited by 37 publications

(10 citation statements)

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“…The actual basis for the discrepancies between our observations is not completely clear. Several differences in experimental protocol warrant attention, however: (i) In the experiments of Parthier et al (21), quantitation (i.e., level of synthetase induction by light) is accomplished by determining the level of acylation (by whole cell extracts) of a heterologous tRNA preparation from Anacystis. The tacit assumption is made that only the chloroplastic synthetases are capable of acylating Anacystis tRNA and that cytoplasmic synthetase cannot catalyze these reactions.…”

Section: Resultsmentioning

confidence: 99%

The Sites of Transcription and Translation for Euglena Chloroplastic Aminoacyl-tRNA Synthetases

Hecker¹,

Egan²,

Reynolds³

et al. 1974

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

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We find that cycloheximide completely blocks the light-induced appearance of Euglena chloroplastic aminoacyl-tRNA synthetases in dark-grown cells of Euglerva gracilis var. baciliaris. Streptomycin, on the other hand, has no effect on the light-induction of these organellar enzymes. These observations, together with the finding that an aplastidic mutant (strain WsBUL, which has neither significant plastid structure nor detectable chloroplast DNA) contains low levels of the chloroplastic synthetases, indicate that the chloroplastic synthetases are transcriptional products of nuclear genes and are translated on cytoplasmic ribosomes prior to compartmentalization within the chloroplasts.The chloroplastic aminoacyl-tRNA synthetases (EC 6.1.1.X) of Euglena have been shown to be quantitatively under the control of light (1) in that exposure of dark-grown cells to light results in a marked increase in the level of these organelle-specific enzymes. In the present report, we have taken advantage of this light inducibility as well as of the techniques developed by Schiff et al. (2, 3). These techniques permit the study of chloroplast development in the absence of such complicating factors as cell growth and cell division in order to de-termine the site of translation of chloroplastic synthetases. More specifically, we examined the effect of streptomycin (4-6) and cycloheximide (7), which block protein synthesis on organelle (68S) and cytoplasmic (87S) ribosomes, respectively, on the light induction of chloroplastic synthetases in "resting" or nondividing dark-grown Euglena.We observe that, while cycloheximide completely blocks induction, streptomycin has no effect upon induction of chloroplast synthetases. In addition, we find as indicated previously (1), that low levels of the chloroplast synthetases are present in strain W3BUL (3,(8)(9)(10), a mutant strain that lacks both detectable chloroplast DNA and chloroplast structure. Thus we interpret our results to indicate that the chloroplast-specific aminoacyl-tRNA synthetases are translated on cytoplasmic ribosomes from transcriptional products of the nuclear genome, and are subsequently compartmentalized within the organelle, as has also been suggested for the NADP: triose phosphate dehydrogenase and alkaline DNase of Euglena (11)(12)(13).Abbreviation: SynPh, chloroplast phenylalanyl-tRNA synthetase.

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Section: Resultsmentioning

confidence: 99%

The Sites of Transcription and Translation for Euglena Chloroplastic Aminoacyl-tRNA Synthetases

Hecker¹,

Egan²,

Reynolds³

et al. 1974

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

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“…The expression of the plastidic AARS enzymes and their tRNA substrates is linked to plastid differentiation and is partly under developmental and light-regulated control. Exposure of dark-grown Euglena cells to light results in a marked increase in the level of plastidic AARS and parallels chloroplast biogenesis (Reger et al, 1970;Parthier et al, 1972;Reinbothe and Parthier, 1990). In cotton, AARSs show a four-to 16-fold increase of expression in cotyledons during germination (Brantner and Dure, 1975).…”

Section: Discussionmentioning

confidence: 99%

Inactivation of a Glycyl-tRNA Synthetase Leads to an Arrest in Plant Embryo Development

Uwer¹,

Willmitzer²,

Altmann³

1998

The Plant Cell

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Embryo formation is the first patterning process during vegetative plant growth. Using transposons as insertional mutagens in Arabidopsis, we identified the mutant edd1 that shows embryo-defective development. The insertion mutation is lethal, arresting embryo growth between the globular and heart stages of embryonic development. The mutant phenotype cosegregates with a transposed Dissociation element. Sequences flanking the transposed element were isolated and used to isolate a full-length cDNA clone representing the wild-type EDD1 gene. Complementation of the mutant through Agrobacterium-mediated gene transfer of an EDD1 wild-type copy as well as loss of the transposon concomitant with phenotypic reversion demonstrated that the transposon had caused the mutation. Based on homology to Escherichia coli , the EDD1 gene is predicted to encode a novel glycyl-tRNA synthetase (GlyRS) that has not been identified previously in higher plants. An N-terminal portion of the plant protein is able to direct a marker protein into pea chloroplasts. Thus, the gene identified by the embryo-defective insertion mutation encodes a GlyRS homolog, probably acting within the plastidic compartment. INTRODUCTIONPattern formation presents one of the most challenging aspects of plant development. It addresses the organizational aspect of development, namely, the origin of diverse cell types, tissues, and organs at specific locations to form a structurally and functionally meaningful context. In flowering plants, most pattern-forming events occur in the postembryonic sporophyte after seed germination. However, the primary plant architecture, which is fairly uniform among flowering plants, is generated during early embryogenesis (reviewed in Jürgens et al., 1991;Jürgens and Mayer, 1994).Formation of the embryo body can be divided conceptually into three overlapping phases (West and Harada, 1993;Jürgens and Mayer, 1994). During the first morphogenetic phase, an apical-basal axis is established throughout the embryo body, with the root apical meristem at one end and the shoot apical meristem at the other. A radial pattern is created by the formation of three primordial tissue layers, that is, protoderm, procambium, and ground meristem, and bilateral symmetry occurs throughout the development of the cotyledons Meinke, 1995).The second phase is characterized by embryo growth and the accumulation of storage reserves (Souèges, 1919;Müller, 1963;Goldberg et al., 1989). During the final phase, the embryo prepares for desiccation, dehydrates, and enters a period of developmental arrest. The ovule develops into the seed, which is surrounded by an elaborated coat that enables the differentiated embryo to survive harsh environmental conditions until germination and sporophytic development are favorable.Higher plant embryogenesis was investigated extensively during the past century (Hanstein, 1870;Vandendries, 1909;Schnarf, 1929;Maheshwari, 1950). Studies using light and electron microscopy have provided detailed descriptions of the morphological and a...

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“…Reger et al (19) showed that chloroplasts contain some tRNAs and aminoacyl tRNA synthetases of their own which differ in chromatographic behavior from the cytoplasmic counterparts. These chloroplast tRNAs and aminoacyl tRNA synthetases have been shown to be absent from darkgrown cells when chloroplast development is suppressed and to be inducible by light (4,18). Furthermore, proplastids and chloroplasts (and the DNA which they contain) can be eliminated from cells by mutagens to yield strains which lack the ability to develop chloroplasts fully (23).…”

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confidence: 99%

Subcellular Localization of Cytokinins in Transfer Ribonucleic Acid

1977

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Evidence on the localization of cytokinins in chloroplast tRNA was obtained by comparison of Euglena gracilis var. bacillaris light-grown and dark-grown wild type cultures and chloroplast-bleached mutant strains. The several cytokinins characteristic of tRNA were separated by Sephadex LH-20 column chromatography of the hydrolysates and were quantitatively determined by tobacco bioassays of the eluates. The results indicate that 6-(3-methyl-2-butenylamino)-9-l3-D-ribofuranosylpurine (i6A) is formed in both the cytoplasmic and chloroplast tRNA, whereas 6-(4-hydroxy-3-methyl-cis-2-butenylamino)-9-fl-D-ribofuranosylpurine (c-io6A) is produced mainly in the cytoplasmic tRNA and 6-(4-hydroxy-3-methyl-2-butenylamiao)-2-methylthio-9-fi-D-ribofuranosylpurine (ms2io6A) is localized exdusively in chloroplast tRNA. The restriction of the methiolation reaction to the chloropbst is supported by results of radioisotope experiments showing that 3S-labeled MgSO4 is incorported into ms2io6A in the wild type cultures, but not in the chloroplast-bleached mutant strains.Preparations of unfractionated tRNAs from various sources of wide evolutionary divergence have been shown to contain cytokinin-active nucleosides (3,12,26). To date, the four major active nucleosides which have been identified in tRNAs are i6A,3 c-io6A, ms2i6A, and ms2io6A. Evidence from various microorganisms shows that i6A and ms2i6A are the two major cytokinins found in their tRNAs (2,6,27). However, c-io6A and ms2io6A have been found in culture filtrates of certain plant pathogens (16,17,20), and recently Thimmappaya and Cherayil (29) 3 Abbreviations: i6A: N6-(A2-isopentenyl)adenosine or 6-(3-methyl-2-butenylamino)-9-/3-D-ribofuranosylpurine; t-io6A: ribosyl-trans-zeatin or 6-(4-hydroxy-3-methyl-trans-2-butenylamino)-9-/3-D-ribofuranosylpurine; c-io6A: ribosyl-cis-zeatin or 6-(4-hydroxy-3-methyl-cis-2-butenylamino)-9-,8--ribofuranosylpurine; ms2i6A: 2-methylthio-NO-isopentenyladenosine or 6-(3-methyl-2-butenylamino)-2-methylthio-9-13D-ribofuranosylpurine; ms2io6A: ribosyl-2-methylthiozeatin or 6-(4-hydroxy-3-methyl-2-butenylamino)-2-methylthio-9-f-D-ribofuranosylpurine; CTAB: cetyltrimethylammonium bromide; KE: kinetin equivalent, defined as the ,ug of kinetin (6-furfurylaminopurine) required to give the same activity as the test sample under the specified conditions. tRNA preparations. Hall et al. (13) have reported c-io6A and i6 A as constituents of plant tRNA, namely from corn kernels, spinach, and frozen peas. Wheat germ tRNA contains four cytokinins, i6A, io6A, and their methylthio derivatives (5). Pea root tRNA hydrolysates have been shown to contain mainly io6A and i6A (25). Vreman et al. (30,31) have reported the presence of i6A, ms2i6A, c-io6A, c-ms2io6A, and t-ms2io06A in tRNA hydrolysates from pea shoots. Thus, the cytokinins show greater diversity in plant tRNAs than in animal tRNAs or than generally found in tRNAs of microorganisms. The presence of different cytokinins in tRNAs of a single organism raises questions as to their origin and pos...

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Light-stimulated synthesis of aminoacyl-tRNA synthetases in greening Euglena gracilis

Cited by 37 publications

References 10 publications

The Sites of Transcription and Translation for Euglena Chloroplastic Aminoacyl-tRNA Synthetases

The Sites of Transcription and Translation for Euglena Chloroplastic Aminoacyl-tRNA Synthetases

Inactivation of a Glycyl-tRNA Synthetase Leads to an Arrest in Plant Embryo Development

Subcellular Localization of Cytokinins in Transfer Ribonucleic Acid

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