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Balasco Serrão VH, Minari K, Pereira HD, Thiemann OH. Bacterial selenocysteine synthase structure revealed by single-particle cryoEM. Curr Res Struct Biol 2024; 7:100143. [PMID: 38681238 PMCID: PMC11047290 DOI: 10.1016/j.crstbi.2024.100143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 03/31/2024] [Accepted: 04/09/2024] [Indexed: 05/01/2024] Open
Abstract
The 21st amino acid, selenocysteine (Sec), is synthesized on its dedicated transfer RNA (tRNASec). In bacteria, Sec is synthesized from Ser-tRNA[Ser]Sec by Selenocysteine Synthase (SelA), which is a pivotal enzyme in the biosynthesis of Sec. The structural characterization of bacterial SelA is of paramount importance to decipher its catalytic mechanism and its role in the regulation of the Sec-synthesis pathway. Here, we present a comprehensive single-particle cryo-electron microscopy (SPA cryoEM) structure of the bacterial SelA with an overall resolution of 2.69 Å. Using recombinant Escherichia coli SelA, we purified and prepared samples for single-particle cryoEM. The structural insights from SelA, combined with previous in vivo and in vitro knowledge, underscore the indispensable role of decamerization in SelA's function. Moreover, our structural analysis corroborates previous results that show that SelA adopts a pentamer of dimers configuration, and the active site architecture, substrate binding pocket, and key K295 catalytic residue are identified and described in detail. The differences in protein architecture and substrate coordination between the bacterial enzyme and its counterparts offer compelling structural evidence supporting the independent molecular evolution of the bacterial and archaea/eukarya Ser-Sec biosynthesis present in the natural world.
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Affiliation(s)
- Vitor Hugo Balasco Serrão
- Biomolecular Cryoelectron Microscopy Facility, University of California - Santa Cruz, Santa Cruz, CA, 95064, United States
- Department of Chemistry and Biochemistry, University of California - Santa Cruz, Santa Cruz, CA, 95064, United States
| | - Karine Minari
- Biomolecular Engineering Department, Jack Baskin School of Engineering, University of California - Santa Cruz, Santa Cruz, CA, 95064, United States
| | - Humberto D'Muniz Pereira
- Physics Institute of Sao Carlos, University of Sao Paulo, Trabalhador Sao Carlense Av., 400, São Carlos, SP, CEP 13566-590, Brazil
| | - Otavio Henrique Thiemann
- Physics Institute of Sao Carlos, University of Sao Paulo, Trabalhador Sao Carlense Av., 400, São Carlos, SP, CEP 13566-590, Brazil
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Tsuji PA, Santesmasses D, Lee BJ, Gladyshev VN, Hatfield DL. Historical Roles of Selenium and Selenoproteins in Health and Development: The Good, the Bad and the Ugly. Int J Mol Sci 2021; 23:ijms23010005. [PMID: 35008430 PMCID: PMC8744743 DOI: 10.3390/ijms23010005] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/25/2022] Open
Abstract
Selenium is a fascinating element that has a long history, most of which documents it as a deleterious element to health. In more recent years, selenium has been found to be an essential element in the diet of humans, all other mammals, and many other life forms. It has many health benefits that include, for example, roles in preventing heart disease and certain forms of cancer, slowing AIDS progression in HIV patients, supporting male reproduction, inhibiting viral expression, and boosting the immune system, and it also plays essential roles in mammalian development. Elucidating the molecular biology of selenium over the past 40 years generated an entirely new field of science which encompassed the many novel features of selenium. These features were (1) how this element makes its way into protein as the 21st amino acid in the genetic code, selenocysteine (Sec); (2) the vast amount of machinery dedicated to synthesizing Sec uniquely on its tRNA; (3) the incorporation of Sec into protein; and (4) the roles of the resulting Sec-containing proteins (selenoproteins) in health and development. One of the research areas receiving the most attention regarding selenium in health has been its role in cancer prevention, but further research has also exposed the role of this element as a facilitator of various maladies, including cancer.
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Affiliation(s)
- Petra A. Tsuji
- Department of Biological Sciences, Towson University, 8000 York Rd., Towson, MD 21252, USA
- Correspondence:
| | - Didac Santesmasses
- Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02215, USA; (D.S.); (V.N.G.)
| | - Byeong J. Lee
- School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Korea;
| | - Vadim N. Gladyshev
- Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02215, USA; (D.S.); (V.N.G.)
| | - Dolph L. Hatfield
- Scientist Emeritus, Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA;
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Fradejas-Villar N, Bohleber S, Zhao W, Reuter U, Kotter A, Helm M, Knoll R, McFarland R, Taylor RW, Mo Y, Miyauchi K, Sakaguchi Y, Suzuki T, Schweizer U. The Effect of tRNA [Ser]Sec Isopentenylation on Selenoprotein Expression. Int J Mol Sci 2021; 22:ijms222111454. [PMID: 34768885 PMCID: PMC8583801 DOI: 10.3390/ijms222111454] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 12/22/2022] Open
Abstract
Transfer RNA[Ser]Sec carries multiple post-transcriptional modifications. The A37G mutation in tRNA[Ser]Sec abrogates isopentenylation of base 37 and has a profound effect on selenoprotein expression in mice. Patients with a homozygous pathogenic p.R323Q variant in tRNA-isopentenyl-transferase (TRIT1) show a severe neurological disorder, and hence we wondered whether selenoprotein expression was impaired. Patient fibroblasts with the homozygous p.R323Q variant did not show a general decrease in selenoprotein expression. However, recombinant human TRIT1R323Q had significantly diminished activities towards several tRNA substrates in vitro. We thus engineered mice conditionally deficient in Trit1 in hepatocytes and neurons. Mass-spectrometry revealed that hypermodification of U34 to mcm5Um occurs independently of isopentenylation of A37 in tRNA[Ser]Sec. Western blotting and 75Se metabolic labeling showed only moderate effects on selenoprotein levels and 75Se incorporation. A detailed analysis of Trit1-deficient liver using ribosomal profiling demonstrated that UGA/Sec re-coding was moderately affected in Selenop, Txnrd1, and Sephs2, but not in Gpx1. 2′O-methylation of U34 in tRNA[Ser]Sec depends on FTSJ1, but does not affect UGA/Sec re-coding in selenoprotein translation. Taken together, our results show that a lack of isopentenylation of tRNA[Ser]Sec affects UGA/Sec read-through but differs from a A37G mutation.
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Affiliation(s)
- Noelia Fradejas-Villar
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, D-53115 Bonn, Germany; (N.F.-V.); (S.B.); (W.Z.); (U.R.); (R.K.)
| | - Simon Bohleber
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, D-53115 Bonn, Germany; (N.F.-V.); (S.B.); (W.Z.); (U.R.); (R.K.)
| | - Wenchao Zhao
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, D-53115 Bonn, Germany; (N.F.-V.); (S.B.); (W.Z.); (U.R.); (R.K.)
| | - Uschi Reuter
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, D-53115 Bonn, Germany; (N.F.-V.); (S.B.); (W.Z.); (U.R.); (R.K.)
| | - Annika Kotter
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Staudingerweg 5, D-55128 Mainz, Germany; (A.K.); (M.H.)
| | - Mark Helm
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Staudingerweg 5, D-55128 Mainz, Germany; (A.K.); (M.H.)
| | - Rainer Knoll
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, D-53115 Bonn, Germany; (N.F.-V.); (S.B.); (W.Z.); (U.R.); (R.K.)
| | - Robert McFarland
- Wellcome Centre for Mitochondrial Research, Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (R.M.); (R.W.T.)
| | - Robert W. Taylor
- Wellcome Centre for Mitochondrial Research, Clinical and Translational Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK; (R.M.); (R.W.T.)
| | - Yufeng Mo
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; (Y.M.); (K.M.); (Y.S.); (T.S.)
| | - Kenjyo Miyauchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; (Y.M.); (K.M.); (Y.S.); (T.S.)
| | - Yuriko Sakaguchi
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; (Y.M.); (K.M.); (Y.S.); (T.S.)
| | - Tsutomu Suzuki
- Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo 113-8656, Japan; (Y.M.); (K.M.); (Y.S.); (T.S.)
| | - Ulrich Schweizer
- Institut für Biochemie und Molekularbiologie, Rheinische Friedrich-Wilhelms-Universität Bonn, D-53115 Bonn, Germany; (N.F.-V.); (S.B.); (W.Z.); (U.R.); (R.K.)
- Correspondence:
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