Translation reinitiation and development are compromised in similar ways by mutations in translation initiation factor eIF3h and the ribosomal protein RPL24.
BACKGROUND
Within the scanning model of translation initiation, reinitiation is a non-canonical mechanism that operates on mRNAs harboring upstream open reading frames. The h subunit of eukaryotic initiation factor 3 (eIF3) boosts translation reinitiation on the uORF-containing mRNA coding for the Arabidopsis bZip transcription factor, AtbZip11, among others. The RPL24B protein of the large ribosomal subunit, which is encoded by SHORT VALVE1, likewise fosters translation of uORF-containing mRNAs, for example mRNAs for auxin response transcription factors (ARFs).


RESULTS
Here we tested the hypothesis that RPL24B and eIF3h affect translation reinitiation in a similar fashion. First, like eif3h mutants, rpl24b mutants under-translate the AtbZip11 mRNA, and the detailed spectrum of translational defects in rpl24b is remarkably similar to that of eif3h. Second, eif3h mutants display defects in auxin mediated organogenesis and gene expression, similar to rpl24b. Like AtbZip11, the uORF-containing ARF mRNAs are indeed undertranslated in eif3h mutant seedlings.


CONCLUSIONS
We conclude that, similar to eIF3h, RPL24B bolsters the reinitiation competence of uORF-translating ribosomes. Coordination between eIF3 and the large ribosomal subunit helps to fine-tune translation of uORF-containing mRNAs and, in turn, to orchestrate plant development.
Zhou
Fujun
F
Genome Science and Technology Program, The University of Tennessee, Knoxville, TN 37996, USA.
Roy
Bijoyita
B
von Arnim
Albrecht G
AG
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics* / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D009154:Mutation; D016366:Open Reading Frames; D010442:Peptide Chain Initiation, Translational; D012333:RNA, Messenger / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D039621:Eukaryotic Initiation Factor-3; D007210:Indoleacetic Acids; D012333:RNA, Messenger; D012269:Ribosomal Proteins; D014157:Transcription Factors; C036298:ribosomal protein L24
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