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Brito Querido J, Díaz-López I, Ramakrishnan V. The molecular basis of translation initiation and its regulation in eukaryotes. Nat Rev Mol Cell Biol 2024; 25:168-186. [PMID: 38052923 DOI: 10.1038/s41580-023-00624-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2023] [Indexed: 12/07/2023]
Abstract
The regulation of gene expression is fundamental for life. Whereas the role of transcriptional regulation of gene expression has been studied for several decades, it has been clear over the past two decades that post-transcriptional regulation of gene expression, of which translation regulation is a major part, can be equally important. Translation can be divided into four main stages: initiation, elongation, termination and ribosome recycling. Translation is controlled mainly during its initiation, a process which culminates in a ribosome positioned with an initiator tRNA over the start codon and, thus, ready to begin elongation of the protein chain. mRNA translation has emerged as a powerful tool for the development of innovative therapies, yet the detailed mechanisms underlying the complex process of initiation remain unclear. Recent studies in yeast and mammals have started to shed light on some previously unclear aspects of this process. In this Review, we discuss the current state of knowledge on eukaryotic translation initiation and its regulation in health and disease. Specifically, we focus on recent advances in understanding the processes involved in assembling the 43S pre-initiation complex and its recruitment by the cap-binding complex eukaryotic translation initiation factor 4F (eIF4F) at the 5' end of mRNA. In addition, we discuss recent insights into ribosome scanning along the 5' untranslated region of mRNA and selection of the start codon, which culminates in joining of the 60S large subunit and formation of the 80S initiation complex.
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Affiliation(s)
- Jailson Brito Querido
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Irene Díaz-López
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - V Ramakrishnan
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
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Wang J, Liu J, Guo Z. Natural uORF variation in plants. TRENDS IN PLANT SCIENCE 2024; 29:290-302. [PMID: 37640640 DOI: 10.1016/j.tplants.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 07/04/2023] [Accepted: 07/19/2023] [Indexed: 08/31/2023]
Abstract
Taking advantage of natural variation promotes our understanding of phenotypic diversity and trait evolution, ultimately accelerating plant breeding, in which the identification of causal variations is critical. To date, sequence variations in the coding region and transcription level polymorphisms caused by variations in the promoter have been prioritized. An upstream open reading frame (uORF) in the 5' untranslated region (5' UTR) regulates gene expression at the post-transcription or translation level. In recent years, studies have demonstrated that natural uORF variations shape phenotypic diversity. This opinion article highlights recent researches and speculates on future directions for natural uORF variation in plants.
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Affiliation(s)
- Jiangen Wang
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Juhong Liu
- Fuzhou Institute for Data Technology Co., Ltd., Fuzhou 350207, China
| | - Zilong Guo
- Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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Hernández G, García A, Weingarten-Gabbay S, Mishra R, Hussain T, Amiri M, Moreno-Hagelsieb G, Montiel-Dávalos A, Lasko P, Sonenberg N. Functional analysis of the AUG initiator codon context reveals novel conserved sequences that disfavor mRNA translation in eukaryotes. Nucleic Acids Res 2024; 52:1064-1079. [PMID: 38038264 PMCID: PMC10853783 DOI: 10.1093/nar/gkad1152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 11/09/2023] [Accepted: 11/15/2023] [Indexed: 12/02/2023] Open
Abstract
mRNA translation is a fundamental process for life. Selection of the translation initiation site (TIS) is crucial, as it establishes the correct open reading frame for mRNA decoding. Studies in vertebrate mRNAs discovered that a purine at -3 and a G at +4 (where A of the AUG initiator codon is numbered + 1), promote TIS recognition. However, the TIS context in other eukaryotes has been poorly experimentally analyzed. We analyzed in vitro the influence of the -3, -2, -1 and + 4 positions of the TIS context in rabbit, Drosophila, wheat, and yeast. We observed that -3A conferred the best translational efficiency across these species. However, we found variability at the + 4 position for optimal translation. In addition, the Kozak motif that was defined from mammalian cells was only weakly predictive for wheat and essentially non-predictive for yeast. We discovered eight conserved sequences that significantly disfavored translation. Due to the big differences in translational efficiency observed among weak TIS context sequences, we define a novel category that we termed 'barren AUG context sequences (BACS)', which represent sequences disfavoring translation. Analysis of mRNA-ribosomal complexes structures provided insights into the function of BACS. The gene ontology of the BACS-containing mRNAs is presented.
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Affiliation(s)
- Greco Hernández
- mRNA and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (INCan), Mexico City 14080, Mexico
| | - Alejandra García
- mRNA and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (INCan), Mexico City 14080, Mexico
| | - Shira Weingarten-Gabbay
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Rishi Kumar Mishra
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru-560012, India
| | - Tanweer Hussain
- Department of Developmental Biology and Genetics, Indian Institute of Science, Bengaluru-560012, India
| | - Mehdi Amiri
- Department of Biochemistry and Goodman Cancer Institute. McGill University., Montreal, QC H3A 1A3, Canada
| | - Gabriel Moreno-Hagelsieb
- Department of Biology, Wilfrid Laurier University. 75 University Ave. W, Waterloo, ON N2L 3C5, Canada
| | - Angélica Montiel-Dávalos
- mRNA and Cancer Laboratory, Unit of Biomedical Research on Cancer, National Institute of Cancer (INCan), Mexico City 14080, Mexico
| | - Paul Lasko
- Department of Biology, McGill University. Montreal, QC H3G 0B1, Canada
| | - Nahum Sonenberg
- Department of Biochemistry and Goodman Cancer Institute. McGill University., Montreal, QC H3A 1A3, Canada
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Wang J, Zhang G, Qian W, Li K. Decoding the Heterogeneity and Specialized Function of Translation Machinery Through Ribosome Profiling in Yeast Mutants of Initiation Factors. Adv Biol (Weinh) 2024; 8:e2300494. [PMID: 37997253 DOI: 10.1002/adbi.202300494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 09/24/2023] [Indexed: 11/25/2023]
Abstract
The nuanced heterogeneity and specialized functions of translation machinery are increasingly recognized as crucial for precise translational regulation. Here, high-throughput ribosomal profiling (ribo-seq) is used to analyze the specialized roles of eukaryotic initiation factors (eIFs) in the budding yeast. By examining changes in ribosomal distribution across the genome resulting from knockouts of eIF4A, eIF4B, eIF4G1, CAF20, or EAP1, or knockdowns of eIF1, eIF1A, eIF4E, or PAB1, two distinct initiation-factor groups, the "looping" and "scanning" groups are discerned, based on similarities in the ribosomal landscapes their perturbation induced. The study delves into the cis-regulatory sequence features of genes influenced predominantly by each group, revealing that genes more dependent on the looping-group factors generally have shorter transcripts and poly(A) tails. In contrast, genes more dependent on the scanning-group factors often possess upstream open reading frames and exhibit a higher GC content in their 5' untranslated regions. From the ribosomal RNA fragments identified in the ribo-seq data, ribosomal heterogeneity associated with perturbation of specific initiation factors is further identified, suggesting their potential roles in regulating ribosomal components. Collectively, the study illuminates the complexity of translational regulation driven by heterogeneity and specialized functions of translation machinery, presenting potential approaches for targeted gene translation manipulation.
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Affiliation(s)
- Jia Wang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
| | - Geyu Zhang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wenfeng Qian
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ke Li
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China
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Ardern Z. Alternative Reading Frames are an Underappreciated Source of Protein Sequence Novelty. J Mol Evol 2023; 91:570-580. [PMID: 37326679 DOI: 10.1007/s00239-023-10122-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 05/31/2023] [Indexed: 06/17/2023]
Abstract
Protein-coding DNA sequences can be translated into completely different amino acid sequences if the nucleotide triplets used are shifted by a non-triplet amount on the same DNA strand or by translating codons from the opposite strand. Such "alternative reading frames" of protein-coding genes are a major contributor to the evolution of novel protein products. Recent studies demonstrating this include examples across the three domains of cellular life and in viruses. These sequences increase the number of trials potentially available for the evolutionary invention of new genes and also have unusual properties which may facilitate gene origin. There is evidence that the structure of the standard genetic code contributes to the features and gene-likeness of some alternative frame sequences. These findings have important implications across diverse areas of molecular biology, including for genome annotation, structural biology, and evolutionary genomics.
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Mangkalaphiban K, Ganesan R, Jacobson A. Direct and indirect consequences of PAB1 deletion in the regulation of translation initiation, translation termination, and mRNA decay. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543082. [PMID: 37398227 PMCID: PMC10312514 DOI: 10.1101/2023.05.31.543082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Cytoplasmic poly(A)-binding protein (PABPC; Pab1 in yeast) is thought to be involved in multiple steps of post-transcriptional control, including translation initiation, translation termination, and mRNA decay. To understand these roles of PABPC in more detail for endogenous mRNAs, and to distinguish its direct effects from indirect effects, we have employed RNA-Seq and Ribo-Seq to analyze changes in the abundance and translation of the yeast transcriptome, as well as mass spectrometry to assess the abundance of the components of the yeast proteome, in cells lacking the PAB1 gene. We observed drastic changes in the transcriptome and proteome, as well as defects in translation initiation and termination, in pab1Δ cells. Defects in translation initiation and the stabilization of specific classes of mRNAs in pab1Δ cells appear to be partly indirect consequences of reduced levels of specific initiation factors, decapping activators, and components of the deadenylation complex in addition to the general loss of Pab1's direct role in these processes. Cells devoid of Pab1 also manifested a nonsense codon readthrough phenotype indicative of a defect in translation termination, but this defect may be a direct effect of the loss of Pab1 as it could not be attributed to significant reductions in the levels of release factors.
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Affiliation(s)
- Kotchaphorn Mangkalaphiban
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, 368 Plantation Street, Worcester, MA 01655
| | - Robin Ganesan
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, 368 Plantation Street, Worcester, MA 01655
| | - Allan Jacobson
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, 368 Plantation Street, Worcester, MA 01655
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Kong J, Zhang S, Qian W, Li K. Synonymous somatic mutations that alter proximal out-of-frame downstream ATGs are associated with aberrant gene expression levels in cancer cells. J Genet Genomics 2023:S1673-8527(23)00052-8. [PMID: 36898610 DOI: 10.1016/j.jgg.2023.02.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/21/2023] [Accepted: 02/28/2023] [Indexed: 03/12/2023]
Affiliation(s)
- Jinhui Kong
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuo Zhang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenfeng Qian
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ke Li
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China.
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