Mutations in eIF5B Confer Thermosensitive and Pleiotropic Phenotypes via Translation Defects in Arabidopsis thaliana

• Published in: The Plant cell 2017-08, Vol.29 (8), p.1952-1969
• Main Authors: Zhang, Liyuan, Liu, Xinye, Gaikwad, Kishor, Kou, Xiaoxia, Wang, Fei, Tian, Xuejun, Xin, Mingming, Ni, Zhongfu, Sun, Qixin, Peng, Huiru, Vierling, Elizabeth
• Format: Article
• Language: English
• Subjects: Acclimation; Acclimatization; Alleles; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Deoxyribonucleic acid; DNA; DNA, Bacterial - genetics; Electron transport; Electron Transport - genetics; Eukaryotic Initiation Factors - genetics; Eukaryotic Initiation Factors - metabolism; Gene Expression Regulation, Plant; Genes; Genetic Complementation Test; Genetic Pleiotropy; Growth conditions; Guanosine triphosphatases; Heat; Heat stress; Heat tolerance; Heat-Shock Response - genetics; High temperature; Indoleacetic Acids - metabolism; Initiation factor eIF-5B; Missense mutation; mRNA; Mutagenesis, Insertional; Mutation; Mutation - genetics; Phenotype; Phylogeny; Plant Development; Polyribosomes; Polyribosomes - metabolism; Protein Biosynthesis - genetics; Proteins; Ribonucleic acid; RNA; RNA, Messenger - genetics; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; T-DNA; Temperature; Thermotolerance; Time Factors
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.16.00808

The conserved eukaryotic translation initiation factor 5B, eIF5B, is a GTPase that acts late in translation initiation. We found that an Arabidopsis thaliana mutant sensitive to hot temperatures 3 (hot3-1), which behaves as the wild type in the absence of stress but is unable to acclimate to high temperature, carries a missense mutation in the eIF5B1 gene (At1g76810), producing a temperature sensitive protein. A more severe, T-DNA insertion allele (hot3-2) causes pleiotropic developmental phenotypes. Surprisingly, Arabidopsis has three other eIF5B genes that do not substitute for eIF5B1; two of these appear to be in the process of pseudogenization. Polysome profiling and RNA-seq analysis of hot3-1 plants show delayed recovery of polysomes after heat stress and reduced translational efficiency (TE) of a subset of stress protective proteins, demonstrating the critical role of translational control early in heat acclimation. Plants carrying the severe hot3-2 allele show decreased TE of auxin-regulated, ribosome-related, and electron transport genes, even under optimal growth conditions. The hot3-2 data suggest that disrupting specific eIF5B interactions on the ribosome can, directly or indirectly, differentially affect translation. Thus, modulating eIF5B interactions could be another mechanism of gene-specific translational control.