5 results on '"von Arnim, Albrecht G."'
Search Results
2. YABBYs and the Transcriptional Corepressors LEUNIG and LEUNIG_HOMOLOG Maintain Leaf Polarity and Meristem Activity in Arabidopsis.
- Author
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Stahle, Melissa I., Kuehlich, Janine, Staron, Lindsay, Von Arnim, Albrecht G., and Golz, John F.
- Subjects
GENETIC repressors ,LEAVES ,MERISTEMS ,ARABIDOPSIS ,ARABIDOPSIS thaliana ,PLANT proteins ,SHOOT apical meristems ,PLANT development - Abstract
In Arabidopsis thaliana, FILAMENTOUS FLOWER (FIL) and YABBY3 (YAB3) encode YABBY domain proteins that regulate abaxial patterning, growth of lateral organs, and inflorescence phyllotaxy. In this study, we show that YABs physically interact with components of a transcriptional repressor complex that include LEUNIG (LUG), LEUNIG_HOMOLOG (LUH), the LUG-associated coregulator SEUSS, and related SEUSS-LIKE proteins. Consistent with the formation of a LUG-YAB complex, we find that lug mutants enhance the polarity and growth defects of fil yab3 mutant leaves and that this enhancement is due to a loss of LUG activity from the abaxial domain. We performed a more extensive genetic analysis, which included the characterization of yab triple and quadruple mutants, lug luh/+ (heterozygous only for luh) mutants, and plants expressing artificial microRNAs targeting LUG or LUH. These analyses showed that the LUG-YAB complex also promotes adaxial cell identity in leaves as well as embryonic shoot apical meristem (SAM) initiation and postembryonic SAM maintenance. Based on the likely formation of the LUG-YAB complex in the abaxial domain of cotyledons and leaves, we propose that this complex has numerous non-cell-autonomous functions during plant development. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
3. Translational Regulation via 5′ mRNA Leader Sequences Revealed by Mutational Analysis of the Arabidopsis Translation Initiation Factor Subunit eIF3h.
- Author
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Tae-Houn Kim, Byung-Hoon Kim, Yahalom, Avital, Chamovitz, Daniel A., and Von Arnim, Albrecht G.
- Subjects
TRANSCRIPTION factors ,CELL growth ,CELL proliferation ,MESSENGER RNA ,LEUCINE zippers ,ARABIDOPSIS thaliana - Abstract
Eukaryotic translation initiation factor 3 (eIF3) consists of core subunits that are conserved from yeast to man as well as less conserved, noncore, subunits with potential regulatory roles. Whereas core subunits tend to be indispensable for cell growth, the roles of the noncore subunits remain poorly understood. We addressed the hypothesis that eIF3 noncore subunits have accessory functions that help to regulate translation initiation, by focusing on the Arabidopsis thaliana eIF3h subunit. Indeed, eIF3h was not essential for general protein translation. However, results from transient expression assays and polysome fractionation indicated that the translation efficiency of specific 5′ mRNA leader sequences was compromised in an eif3h mutant, including the mRNA for the basic domain leucine zipper (bZip) transcription factor ATB2/AtbZip11, translation of which is regulated by sucrose. Among other pleiotropic developmental defects, the eif3h mutant required exogenous sugar to transit from seedling to vegetative development, but it was hypersensitive to elevated levels of exogenous sugars. The ATB2 mRNA was rendered sensitive to the eIF3h level by a series of upstream open reading frames. Moreover, eIF3h could physically interact with subunits of the COP9 signalosome, a protein complex implicated primarily in the regulation of protein ubiquitination, supporting a direct biochemical connection between translation initiation and protein turnover. Together, these data implicate eIF3 in mRNA-associated translation initiation events, such as scanning, start codon recognition, or reinitiation and suggest that poor translation initiation of specific mRNAs contributes to the pleiotropic spectrum of phenotypic defects in the eif3h mutant. [ABSTRACT FROM AUTHOR]
- Published
- 2004
- Full Text
- View/download PDF
4. Light Activates the Translational Regulatory Kinase GCN2 via Reactive Oxygen Species Emanating from the Chloroplast.
- Author
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Lokdarshi A, Guan J, Urquidi Camacho RA, Cho SK, Morgan PW, Leonard M, Shimono M, Day B, and von Arnim AG
- Subjects
- Chitin metabolism, Eukaryotic Initiation Factor-2 metabolism, Gene Ontology, Herbicides toxicity, Hydrogen Peroxide pharmacology, Mutation genetics, Phosphorylation radiation effects, Photosynthesis drug effects, Ribosomes drug effects, Ribosomes metabolism, Ribosomes radiation effects, Seedlings drug effects, Seedlings growth & development, Seedlings radiation effects, Transcriptome genetics, Arabidopsis enzymology, Arabidopsis radiation effects, Arabidopsis Proteins metabolism, Chloroplasts metabolism, Chloroplasts radiation effects, Light, Protein Biosynthesis radiation effects, Protein Kinases metabolism, Reactive Oxygen Species metabolism
- Abstract
Cytosolic mRNA translation is subject to global and mRNA-specific controls. Phosphorylation of the translation initiation factor eIF2α anchors a reversible regulatory switch that represses cytosolic translation globally. The stress-responsive GCN2 kinase is the only known kinase for eIF2α serine 56 in Arabidopsis ( Arabidopsis thaliana ). Here, we show that conditions that generate reactive oxygen species (ROS) in the chloroplast, including dark-light transitions, high light, and the herbicide methyl viologen, rapidly activated GCN2 kinase, whereas mitochondrial and endoplasmic reticulum stress did not. GCN2 activation was light dependent and mitigated by photosynthesis inhibitors and ROS quenchers. Accordingly, the seedling growth of multiple Arabidopsis gcn2 mutants was retarded under excess light conditions, implicating the GCN2-eIF2α pathway in responses to light and associated ROS. Once activated, GCN2 kinase preferentially suppressed the ribosome loading of mRNAs for functions such as mitochondrial ATP synthesis, the chloroplast thylakoids, vesicle trafficking, and translation. The gcn2 mutant overaccumulated transcripts functionally related to abiotic stress, including oxidative stress, as well as innate immune responses. Accordingly, gcn2 displayed defects in immune priming by the fungal elicitor, chitin. Therefore, we provide evidence that reactive oxygen species produced by the photosynthetic apparatus help activate the highly conserved GCN2 kinase, leading to eIF2α phosphorylation and thus affecting the status of the cytosolic protein synthesis apparatus., (© 2020 American Society of Plant Biologists. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
5. Translational regulation via 5' mRNA leader sequences revealed by mutational analysis of the Arabidopsis translation initiation factor subunit eIF3h.
- Author
-
Kim TH, Kim BH, Yahalom A, Chamovitz DA, and von Arnim AG
- Subjects
- Amino Acid Sequence, Arabidopsis metabolism, Arabidopsis Proteins biosynthesis, Arabidopsis Proteins genetics, Basic-Leucine Zipper Transcription Factors, COP9 Signalosome Complex, DNA Mutational Analysis, Eukaryotic Initiation Factor-3 biosynthesis, Eukaryotic Initiation Factors genetics, Genetic Complementation Test, Molecular Sequence Data, Multiprotein Complexes, Mutation genetics, Peptide Hydrolases, Protein Subunits biosynthesis, Protein Subunits genetics, Proteins genetics, Sequence Homology, Amino Acid, Transcription Factors genetics, Ubiquitin genetics, Ubiquitin metabolism, 5' Untranslated Regions genetics, Arabidopsis genetics, Eukaryotic Initiation Factor-3 genetics, Gene Expression Regulation, Plant genetics, Protein Biosynthesis genetics, RNA, Messenger genetics
- Abstract
Eukaryotic translation initiation factor 3 (eIF3) consists of core subunits that are conserved from yeast to man as well as less conserved, noncore, subunits with potential regulatory roles. Whereas core subunits tend to be indispensable for cell growth, the roles of the noncore subunits remain poorly understood. We addressed the hypothesis that eIF3 noncore subunits have accessory functions that help to regulate translation initiation, by focusing on the Arabidopsis thaliana eIF3h subunit. Indeed, eIF3h was not essential for general protein translation. However, results from transient expression assays and polysome fractionation indicated that the translation efficiency of specific 5' mRNA leader sequences was compromised in an eif3h mutant, including the mRNA for the basic domain leucine zipper (bZip) transcription factor ATB2/AtbZip11, translation of which is regulated by sucrose. Among other pleiotropic developmental defects, the eif3h mutant required exogenous sugar to transit from seedling to vegetative development, but it was hypersensitive to elevated levels of exogenous sugars. The ATB2 mRNA was rendered sensitive to the eIF3h level by a series of upstream open reading frames. Moreover, eIF3h could physically interact with subunits of the COP9 signalosome, a protein complex implicated primarily in the regulation of protein ubiquitination, supporting a direct biochemical connection between translation initiation and protein turnover. Together, these data implicate eIF3 in mRNA-associated translation initiation events, such as scanning, start codon recognition, or reinitiation and suggest that poor translation initiation of specific mRNAs contributes to the pleiotropic spectrum of phenotypic defects in the eif3h mutant.
- Published
- 2004
- Full Text
- View/download PDF
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