1
|
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] [Abstract] [Key Words] [Grants] [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.
Collapse
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
| |
Collapse
|
2
|
Ma R, Shao S, Wei S, Ye J, Yang Y, Jiao N, Zhang R. A Novel Phage Infecting the Marine Photoheterotrophic Bacterium Citromicrobium bathyomarinum. Viruses 2022; 14:v14030512. [PMID: 35336919 PMCID: PMC8953757 DOI: 10.3390/v14030512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/26/2022] [Accepted: 03/01/2022] [Indexed: 02/05/2023] Open
Abstract
This study isolated and characterized a new phage infecting the marine photoheterotrophic bacterium Citromicrobium bathyomarinum, which fills the gap in research on phages targeting this ecologically important species. The phage vB_CbaS-RXM (RXM) has a dsDNA genome with a length of 104,206 bp and G+C content of 61.64%. The taxonomic analysis found a close evolutionary relationship between RXM, Erythrobacter phage vB_EliS-L02, and Sphingobium phage Lacusarx, and we propose that RXM represents a new species of the Lacusarxvirus genus. A one-step growth curve revealed a burst size of 75 plaque-forming units (PFUs) per cell in a 3-hour infection cycle. The lysis profile of RXM showed an intraspecific lethal rate of 26.3% against 38 citromicrobial strains. RXM contains 15 auxiliary metabolic genes (AMGs) related to diverse cellular processes, such as putative metabolic innovation and hijacking of host nucleotide metabolism to enhance its biosynthetic capacity. An in-depth analysis showed that phage functional genes strongly rely on the host for translation, while the translation of unique phage genes with less host dependency may be complemented by phage tRNA. Overall, our study investigated the infection kinetics, genetic traits, taxonomy, and predicted roles of AMGs and tRNA genes of this new phage, which contributes to a better understanding of phage diversity and phage–bacterium interactions.
Collapse
Affiliation(s)
- Ruijie Ma
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (R.M.); (S.W.); (Y.Y.); (N.J.)
| | - Shuai Shao
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (S.S.); (J.Y.)
| | - Shuzhen Wei
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (R.M.); (S.W.); (Y.Y.); (N.J.)
| | - Junlei Ye
- College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (S.S.); (J.Y.)
| | - Yahui Yang
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (R.M.); (S.W.); (Y.Y.); (N.J.)
| | - Nianzhi Jiao
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (R.M.); (S.W.); (Y.Y.); (N.J.)
| | - Rui Zhang
- State Key Laboratory of Marine Environmental Science, Fujian Key Laboratory of Marine Carbon Sequestration, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; (R.M.); (S.W.); (Y.Y.); (N.J.)
- Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519080, China
- Correspondence:
| |
Collapse
|
3
|
Serrão VHB, Fernandes ADF, Basso LGM, Scortecci JF, Crusca Júnior E, Cornélio ML, de Souza BM, Palma MS, de Oliveira Neto M, Thiemann OH. The Specific Elongation Factor to Selenocysteine Incorporation in Escherichia coli: Unique tRNA Sec Recognition and its Interactions. J Mol Biol 2021; 433:167279. [PMID: 34624294 DOI: 10.1016/j.jmb.2021.167279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/22/2021] [Accepted: 09/23/2021] [Indexed: 10/20/2022]
Abstract
Several molecular mechanisms are involved in the genetic code interpretation during translation, as codon degeneration for the incorporation of rare amino acids. One mechanism that stands out is selenocysteine (Sec), which requires a specific biosynthesis and incorporation pathway. In Bacteria, the Sec biosynthesis pathway has unique features compared with the eukaryote pathway as Ser to Sec conversion mechanism is accomplished by a homodecameric enzyme (selenocysteine synthase, SelA) followed by the action of an elongation factor (SelB) responsible for delivering the mature Sec-tRNASec into the ribosome by the interaction with the Selenocysteine Insertion Sequence (SECIS). Besides this mechanism being already described, the sequential events for Sec-tRNASec and SECIS specific recognition remain unclear. In this study, we determined the order of events of the interactions between the proteins and RNAs involved in Sec incorporation. Dissociation constants between SelB and the native as well as unacylated-tRNASec variants demonstrated that the acceptor stem and variable arm are essential for SelB recognition. Moreover, our data support the sequence of molecular events where GTP-activated SelB strongly interacts with SelA.tRNASec. Subsequently, SelB.GTP.tRNASec recognizes the mRNA SECIS to deliver the tRNASec to the ribosome. SelB in complex with its specific RNAs were examined using Hydrogen/Deuterium exchange mapping that allowed the determination of the molecular envelopes and its secondary structural variations during the complex assembly. Our results demonstrate the ordering of events in Sec incorporation and contribute to the full comprehension of the tRNASec role in the Sec amino acid biosynthesis, as well as extending the knowledge of synthetic biology and the expansion of the genetic code.
Collapse
Affiliation(s)
- Vitor Hugo Balasco Serrão
- Physics Institute of Sao Carlos, University of Sao Paulo, Trabalhador Sao Carlense Av., 400, São Carlos, SP CEP 13566-590, Brazil; Department of Chemistry and Biochemistry, University California - Santa Cruz, 1156 High St., Santa Cruz, CA 95060, United States
| | - Adriano de Freitas Fernandes
- Physics Institute of Sao Carlos, University of Sao Paulo, Trabalhador Sao Carlense Av., 400, São Carlos, SP CEP 13566-590, Brazil
| | - Luis Guilherme Mansor Basso
- Physical Sciences Laboratory, State University of Northern Rio de Janeiro Darcy Ribeiro - UENF, Av. Alberto Lamego, 2000, 28013-602 Campos dos Goytacazes, RJ, Brazil; Faculty of Science, Philosophy and Letters, University of Sao Paulo, CEP 14040-901 Ribeirão Preto, SP, Brazil
| | - Jéssica Fernandes Scortecci
- Physics Institute of Sao Carlos, University of Sao Paulo, Trabalhador Sao Carlense Av., 400, São Carlos, SP CEP 13566-590, Brazil; Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Science Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Edson Crusca Júnior
- Department of Physical Chemistry, Chemistry Institute of the São Paulo State University - UNESP, CEP 14800-900 Araraquara, SP, Brazil
| | - Marinônio Lopes Cornélio
- Physics Department, Institute of Biosciences, Letters and Exact Sciences (IBILCE), São Paulo State University - UNESP, São Jose do Rio Preto, SP, Brazil
| | - Bibiana Monson de Souza
- Department of General and Applied Biology, Institute of Biosciences of Rio Claro, São Paulo State University - UNESP, Rio Claro, SP, Brazil
| | - Mário Sérgio Palma
- Department of General and Applied Biology, Institute of Biosciences of Rio Claro, São Paulo State University - UNESP, Rio Claro, SP, Brazil
| | - Mario de Oliveira Neto
- Bioscience Institute of Universidade Estadual Paulista, Rubião Jr., Botucatu, SP CEP 18618-000, 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; Department of Genetics and Evolution, Federal University of São Carlos - UFSCar, 13565-905 São Carlos, SP, Brazil.
| |
Collapse
|