Cap‐independent translation of maize <i>Hsp101</i>

Dinkova, Tzvetanka D.; Zepeda, Hilda; Martínez‐Salas, Encarnación; Martínez, Luz María; Nieto-Sotelo, J.; Jiménez, Estela Sánchez de

doi:10.1111/j.1365-313x.2005.02333.x

Cited by 55 publications

(57 citation statements)

References 49 publications

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“…IRES-mediated regulation of translation has been described in eukaryotic cellular mRNAs that are active during mitosis or under stress conditions when cap-dependent translation is inhibited (Pyronnet et al, 2000;Gilbert et al, 2007;Sonenberg and Hinnebusch, 2007), thereby providing a mechanism for continued synthesis of specific proteins when global translation is prevented. Consistent with this, the first IRES identified in plant cells was in mRNA encoding the maize (Zea mays) heat shock protein, Hsp101, and this accounts for its cap-independent translation during heat stress (Dinkova et al, 2005). FCA functions to regulate flowering time by repressing FLC, but we also know it plays other roles in regulating the expression of genome sequences that are also targets of RNA-mediated chromatin silencing and likely acts somewhat redundantly with other autonomous pathway components to regulate a wider set of gene targets (Veley and Michaels, 2008).…”

Section: Discussionsupporting

confidence: 49%

Noncanonical Translation Initiation of theArabidopsisFlowering Time and Alternative Polyadenylation Regulator FCA

et al. 2010

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The RNA binding protein FCA regulates the floral transition and is required for silencing RNAs corresponding to specific noncoding sequences in the Arabidopsis thaliana genome. Through interaction with the canonical RNA 39 processing machinery, FCA affects alternative polyadenylation of many transcripts, including antisense RNAs at the locus encoding the floral repressor FLC. This potential for widespread alteration of gene regulation clearly needs to be tightly regulated, and we have previously shown that FCA expression is autoregulated through poly(A) site choice. Here, we show distinct layers of FCA regulation that involve sequences within the 59 region that regulate noncanonical translation initiation and alter the expression profile. FCA translation in vivo occurs exclusively at a noncanonical CUG codon upstream of the first in-frame AUG. We fully define the upstream flanking sequences essential for its selection, revealing features that distinguish this from other non-AUG start site mechanisms. Bioinformatic analysis identified 10 additional Arabidopsis genes that likely initiate translation at a CUG codon. Our findings reveal further unexpected complexity in the regulation of FCA expression with implications for its roles in regulating flowering time and gene expression and more generally show plant mRNA exceptions to AUG translation initiation.

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Section: Discussionsupporting

confidence: 49%

Noncanonical Translation Initiation of theArabidopsisFlowering Time and Alternative Polyadenylation Regulator FCA

et al. 2010

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“…Because two different mRNA pools exist in germinating seeds, the stored mRNAs, and the de novo-synthesized mRNAs (4,40), it is possible that these different initiation systems allow their respective recruitment during germination. Consistent with this, maize embryonic axes were shown to contain stored mRNAs, some of which are efficiently translated via a cap-independent mechanism during germination (41).…”

Section: Sugarbeet Seeds Use Distinct Mechanisms For Translation Initsupporting

confidence: 52%

Proteome-wide characterization of sugarbeet seed vigor and its tissue specific expression

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et al. 2008

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

123

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Proteomic analysis of mature sugarbeet seeds led to the identification of 759 proteins and their specific tissue expression in root, cotyledons, and perisperm. In particular, the proteome of the perispermic storage tissue found in many seeds of the Caryophyllales is described here. The data allowed us to reconstruct in detail the metabolism of the seeds toward recapitulating facets of seed development and provided insights into complex behaviors such as germination. The seed appears to be well prepared to mobilize the major classes of reserves (the proteins, triglycerides, phytate, and starch) during germination, indicating that the preparation of the seed for germination is mainly achieved during its maturation on the mother plant. Furthermore, the data revealed several pathways that can contribute to seed vigor, an important agronomic trait defined as the potential to produce vigorous seedlings, such as glycine betaine accumulation in seeds. This study also identified several proteins that, to our knowledge, have not previously been described in seeds. For example, the data revealed that the sugarbeet seed can initiate translation either through the traditional cap-dependent mechanism or by a cap-independent process. The study of the tissue specificity of the seed proteome demonstrated a compartmentalization of metabolic activity between the roots, cotyledons, and perisperm, indicating a division of metabolic tasks between the various tissues. Furthermore, the perisperm, although it is known as a dead tissue, appears to be very active biochemically, playing multiple roles in distributing sugars and various metabolites to other tissues of the embryo.) is a dicotyledonous plant of the Amaranthaceae family that has a high economic importance because it is one of the two main sources of sucrose, the other being sugarcane. Furthermore, there is growing interest in the use of this crop to produce bioethanol. The quality of seed germination has a direct impact on the final yield of the culture and is conditioned by the number of plants issued from successful germinations and by the vigor of the seedlings, i.e., the potential to produce vigorous seedlings.The seed is the main form of dissemination of plants. It results from the conversion of a fertilized egg and contains a zygotic embryo (the future plant), one or more storage tissues [a triploid albumen, cotyledon(s), and perisperm] that accumulate the compounds necessary for the embryo's nutrition during germination, and seed coats to ensure the seed's protection against biotic and abiotic stress. A specific feature of sugarbeet is that the maternal nucellus is not fully digested during maturation and gives rise to the central perisperm, in which starch reserves accumulate (1-2). For most plant species growing in temperate climates, seed development ends with a phase of intense desiccation, then the embryo enters a dormant state, allowing its survival for many years. Two phytohormones, abscisic acid (ABA) and gibberellins (GA), play key roles in seed formation, dorm...

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“…For example, an internal ribosome entry site (IRES) in the mRNA allows the ribosome to directly associate with a sequence within the mRNA. Several plant viral RNAs are translated through IRES sequences (Jaag et al, 2003;Dorokhov et al, 2006;Karetnikov and Lehto, 2007), but so far only one cellular plant mRNA was shown to be translated through an IRES-dependent mechanism (Dinkova et al, 2005). Translation of bZIP11 does not depend on IRES as all sequences 3# of the uORF2 can be deleted without affecting translation of the main ORF ( Fig.…”

Section: Translation Of the Bzip11 Main Orfmentioning

confidence: 99%

Sucrose Control of Translation Mediated by an Upstream Open Reading Frame-Encoded Peptide

et al. 2009

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Regulation of gene expression through translational control is common in many organisms. The Arabidopsis (Arabidopsis thaliana) transcription factor bZIP11 is translational repressed in response to sucrose (Suc), resulting in Suc-regulated changes in amino acid metabolism. The 5# leader of the bZIP11 mRNA harbors several upstream open reading frames (uORFs), of which the second uORF is well conserved among bZIP11 homologous genes. The uORF2 element encodes a Suc control peptide (SC-peptide) of 28 residues that is sufficient for imposing Suc-induced repression of translation (SIRT) on a heterologous mRNA. Detailed analysis of the SC-peptide suggests that it functions as an attenuator peptide. Results suggest that the SCpeptide inhibits bZIP11 translation in response to high Suc levels by stalling the ribosome on the mRNA. The conserved noncanonical AUG contexts of bZIP11 uORFs allow inefficient translational initiation of the uORF, resulting in translation initiation of the scanning ribosome at the AUG codon of the bZIP11 main ORF. The results presented show that Suc-dependent signaling mediates differential translation of mRNAs containing SC-peptides encoding uORFs.

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Cap‐independent translation of maize Hsp101

Cited by 55 publications

References 49 publications

Noncanonical Translation Initiation of theArabidopsisFlowering Time and Alternative Polyadenylation Regulator FCA

Noncanonical Translation Initiation of theArabidopsisFlowering Time and Alternative Polyadenylation Regulator FCA

Proteome-wide characterization of sugarbeet seed vigor and its tissue specific expression

Sucrose Control of Translation Mediated by an Upstream Open Reading Frame-Encoded Peptide

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