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Pisareva VP, Pisarev AV. eIF5 and eIF5B together stimulate 48S initiation complex formation during ribosomal scanning. Nucleic Acids Res 2014; 42:12052-69. [PMID: 25260592 PMCID: PMC4231746 DOI: 10.1093/nar/gku877] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
48S initiation complex (48S IC) formation is the first stage in the eukaryotic translation process. According to the canonical mechanism, 40S ribosomal subunit binds to the 5′-end of messenger RNA (mRNA) and scans its 5′-untranslated region (5′-UTR) to the initiation codon where it forms the 48S IC. Entire process is mediated by initiation factors. Here we show that eIF5 and eIF5B together stimulate 48S IC formation influencing initiation codon selection during ribosomal scanning. Initiation on non-optimal start codons—following structured 5′-UTRs, in bad AUG context, within few nucleotides from 5′-end of mRNA and CUG start codon—is the most affected. eIF5-induced hydrolysis of eIF2-bound GTP is essential for stimulation. GTP hydrolysis increases the probability that scanning ribosomal complexes will recognize and arrest scanning at a non-optimal initiation codon. Such 48S ICs are less stable owing to dissociation of eIF2*GDP from initiator tRNA, and eIF5B is then required to stabilize the initiator tRNA in the P site of 40S subunit. Alternative model that eIF5 and eIF5B cause 43S pre-initiation complex rearrangement favoring more efficient initiation codon recognition during ribosomal scanning is equally possible. Mutational analysis of eIF1A and eIF5B revealed distinct functions of eIF5B in 48S IC formation and subunit joining.
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Affiliation(s)
- Vera P Pisareva
- Department of Cell Biology, SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
| | - Andrey V Pisarev
- Department of Cell Biology, SUNY Downstate Medical Center, 450 Clarkson Ave, Brooklyn, NY 11203, USA
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Hiraishi H, Oatman J, Haller SL, Blunk L, McGivern B, Morris J, Papadopoulos E, Gutierrez W, Gordon M, Bokhari W, Ikeda Y, Miles D, Fellers J, Asano M, Wagner G, Tazi L, Rothenburg S, Brown SJ, Asano K. Essential role of eIF5-mimic protein in animal development is linked to control of ATF4 expression. Nucleic Acids Res 2014; 42:10321-30. [PMID: 25147208 PMCID: PMC4176352 DOI: 10.1093/nar/gku670] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Translational control of transcription factor ATF4 through paired upstream ORFs (uORFs) plays an important role in eukaryotic gene regulation. While it is typically induced by phosphorylation of eIF2α, ATF4 translation can be also induced by expression of a translational inhibitor protein, eIF5-mimic protein 1 (5MP1, also known as BZW2) in mammals. Here we show that the 5MP gene is maintained in eukaryotes under strong purifying selection, but is uniquely missing in two major phyla, nematoda and ascomycota. The common function of 5MP from protozoa, plants, fungi and insects is to control translation by inhibiting eIF2. The affinity of human 5MP1 to eIF2β was measured as being equivalent to the published value of human eIF5 to eIF2β, in agreement with effective competition of 5MP with eIF5 for the main substrate, eIF2. In the red flour beetle, Tribolium castaneum, RNA interference studies indicate that 5MP facilitates expression of GADD34, a downstream target of ATF4. Furthermore, both 5MP and ATF4 are essential for larval development. Finally, 5MP and the paired uORFs allowing ATF4 control are conserved in the entire metazoa except nematoda. Based on these findings, we discuss the phylogenetic and functional linkage between ATF4 regulation and 5MP expression in this group of eukaryotes.
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Affiliation(s)
- Hiroyuki Hiraishi
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Jamie Oatman
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Sherry L Haller
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Logan Blunk
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA Arthropod Genomics Center, Kansas State University, Manhattan, KS 66506, USA
| | - Benton McGivern
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA Arthropod Genomics Center, Kansas State University, Manhattan, KS 66506, USA
| | - Jacob Morris
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Evangelos Papadopoulos
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Wade Gutierrez
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA Arthropod Genomics Center, Kansas State University, Manhattan, KS 66506, USA
| | - Michelle Gordon
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA Arthropod Genomics Center, Kansas State University, Manhattan, KS 66506, USA
| | - Wahaj Bokhari
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Yuka Ikeda
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - David Miles
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - John Fellers
- USDA-ARS, Hard WinterWheat Genetics Research Unit, Kansas State University, Manhattan, KS 66506
| | - Masayo Asano
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Gerhard Wagner
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Loubna Tazi
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Stefan Rothenburg
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - Susan J Brown
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA Arthropod Genomics Center, Kansas State University, Manhattan, KS 66506, USA
| | - Katsura Asano
- Molecular Cellular and Developmental Biology Program, Division of Biology, Kansas State University, Manhattan, KS 66506, USA
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