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Daian F, Esper BS, Ashrafi N, Yu GQ, Luciano G, Moorthi S, Luberto C. Regulation of human sphingomyelin synthase 1 translation through its 5'-untranslated region. FEBS Lett 2020; 594:3751-3764. [PMID: 33037626 PMCID: PMC7756225 DOI: 10.1002/1873-3468.13952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 09/04/2020] [Indexed: 11/11/2022]
Abstract
Bcr‐abl1 oncogene causes a shift in the transcription start site of the SMS1 gene (SGMS1) encoding the sphingomyelin (SM) synthesizing enzyme, sphingomyelin synthase 1 (SMS1). This results in an mRNA with a significantly shorter 5′‐UTR, called 7‐SGMS1, which is translated more efficiently than another transcript (IIb‐SGMS1) with a longer 5′UTR in Bcr‐abl1‐positive cells. Here, we determine the effects of these alternative 5′UTRs on SMS1 translation and investigate the key features underlying such regulation. First, the presence of the longer IIb 5′UTR is sufficient to greatly impair translation of a reporter gene. Deletion of the upstream open reading frame (−164 nt) or of the predicted stem‐loops in the 5′UTR of IIb‐SGMS1 has minimal effects on SGMS1 translation. Conversely, deletion of nucleotides −310 to −132 enhanced transcription of IIb‐SGMS1 to reach that of 7‐SGMS1. We thus suggest that regulatory features within nucleotides −310 and −132 modulate IIb‐SGMS1 translation efficiency.
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Affiliation(s)
- Foysal Daian
- Renaissance School of Medicine, Stony Brook University, NY, USA
| | | | - Navid Ashrafi
- Department of Physiology and Biophysics, Stony Brook University, NY, USA
| | - Gui-Qin Yu
- Department of Physiology and Biophysics, Stony Brook University, NY, USA
| | - Gabriella Luciano
- Department of Physiology and Biophysics, Stony Brook University, NY, USA
| | - Sitapriya Moorthi
- Department of Physiology and Biophysics, Stony Brook University, NY, USA
| | - Chiara Luberto
- Department of Physiology and Biophysics, Stony Brook University, NY, USA
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Desai VP, Frank F, Lee A, Righini M, Lancaster L, Noller HF, Tinoco I, Bustamante C. Co-temporal Force and Fluorescence Measurements Reveal a Ribosomal Gear Shift Mechanism of Translation Regulation by Structured mRNAs. Mol Cell 2019; 75:1007-1019.e5. [PMID: 31471187 DOI: 10.1016/j.molcel.2019.07.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 06/12/2019] [Accepted: 07/15/2019] [Indexed: 11/18/2022]
Abstract
The movement of ribosomes on mRNA is often interrupted by secondary structures that present mechanical barriers and play a central role in translation regulation. We investigate how ribosomes couple their internal conformational changes with the activity of translocation factor EF-G to unwind mRNA secondary structures using high-resolution optical tweezers with single-molecule fluorescence capability. We find that hairpin opening occurs during EF-G-catalyzed translocation and is driven by the forward rotation of the small subunit head. Modulating the magnitude of the hairpin barrier by force shows that ribosomes respond to strong barriers by shifting their operation to an alternative 7-fold-slower kinetic pathway prior to translocation. Shifting into a slow gear results from an allosteric switch in the ribosome that may allow it to exploit thermal fluctuations to overcome mechanical barriers. Finally, we observe that ribosomes occasionally open the hairpin in two successive sub-codon steps, revealing a previously unobserved translocation intermediate.
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Affiliation(s)
- Varsha P Desai
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Filipp Frank
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Antony Lee
- Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Maurizio Righini
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Laura Lancaster
- Department of Molecular, Cell, and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Harry F Noller
- Department of Molecular, Cell, and Developmental Biology and Center for Molecular Biology of RNA, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Ignacio Tinoco
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Carlos Bustamante
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Jason L. Choy Laboratory of Single-Molecule Biophysics, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, QB3, University of California, Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Kavli Energy Nanoscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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