Control of cytoplasmic translation in plants

Abstract

Translational control provides cells with a mechanism to rapidly control gene expression in a reversible manner in response to environmental and developmental cues. It involves the dynamic, coordinated activity of numerous factors that direct the synthesis of proteins with precision in space and time. Translational control is primarily regulated at the level of initiation, and as such, mechanisms that regulate translation most often target the initiation machinery. Translation in plants is fundamentally similar to that of other eukaryotes. However, there are significant differences in translation factor isoforms and their associated proteins, and the types of regulation that can act upon these factors. Regulation of translation in plants can involve protein phosphorylation, variable associations of initiation factor isoforms, RNA sequence element interactions, and small RNAs. The assembly of large mRNA-ribonucleoprotein complexes, called processing bodies and stress granules, also influences the translatability of an mRNA. mRNA-cytoskeleton interactions, as well as subcellular and intercellular transport of mRNAs, also appear to regulate translation in plants. Often working together, these control mechanisms finely tune translational expression within the cell.

Mechanism of Cytoplasmic mRNA Translation

“…Several recent reviews on translation provide mechanistic and structural details of translation derived with S. cerevisiae and mammalian systems (Sonenberg and Hinnebusch, 2009;Jackson et al, 2010;Lorsch and Dever, 2010;Hinnebusch, 2011;Aitken and Lorsch, 2012;Dever and Green, 2012;Hernán-dez et al, 2012;Hershey et al, 2012;Hinnebusch and Lorsch, 2012;Valasek, 2012;Voigts-Hoffmann et al, 2012;Lomakin and Steitz, 2013;Hinnebusch, 2014;Mead et al, 2014;Merrick and Harris, 2014). Translation in plants has been reviewed with different emphases in the past five years Muench et al, 2012;Muñoz and Castellano, 2012;Echevarría-Zomeño et al, 2013;Browning, 2014;Gallie, 2014), and several historical reviews provide the back story (Browning, 1996;Bailey-Serres, 1999;Kawaguchi and Bailey-Serres, 2002;Browning, 2004;Gallie, 2007). As will be described, the translational machinery of plants resembles that of S. cerevisiae and mammals.…”

Dynamic Proteomics Emphasizes the Importance of Selective mRNA Translation and Protein Turnover during Arabidopsis Seed Germination

“…Translational Machinery and Selective mRNA TranslationTranslational control is exerted in all stages of plant development and affects a wide range of mRNAs (124,125). Notably, protein synthesis is absolutely required for Arabidopsis seed germination (20), and translational activity is strongly reduced in aged seeds that exhibit depressed seed vigor (26,119).…”

“…The cap-binding complex binds co-transcriptionally to the 5Ј cap of pre-mRNAs and is involved in the maturation, export, and degradation of nuclear mRNAs. In addition, in vitro experiments on maize seed germination showed that stored mRNAs are preferentially translated by the eIF(iso)4E isoform, a component of the cytoplasmic mRNA cap-binding complex (eIF4F) (124,131). Finally, mRNA decay is of importance because impairment in the 3Ј-5Ј exonuclease RRP41L delays germination and inhibits seedling growth (132).…”

Translational Regulation of Cytoplasmic mRNAs

“…An insightful and balanced summary of the plant translation apparatus was presented recently (Muench et al, 2012). The main section on translational control will begin with historical findings from the pre-Arabidopsis era before delving into more recent progress, primarily from Arabidopsis.…”

“…Arabidopsis possesses 29 PUF protein genes, but few potential target mRNAs are known (Francischini and Quaggio, 2009;Muench et al, 2012). The canonical PUF target motif contains a UGUA core, a motif that also functions in human nuclear polyadenylation (Yang et al, 2010).…”