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Gupta K, Wen Y, Ninan NS, Raimer AC, Sharp R, Spring A, Sarachan KL, Johnson MC, Van Duyne GD, Matera AG. Assembly of higher-order SMN oligomers is essential for metazoan viability and requires an exposed structural motif present in the YG zipper dimer. Nucleic Acids Res 2021; 49:7644-7664. [PMID: 34181727 PMCID: PMC8287954 DOI: 10.1093/nar/gkab508] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
Protein oligomerization is one mechanism by which homogenous solutions can separate into distinct liquid phases, enabling assembly of membraneless organelles. Survival Motor Neuron (SMN) is the eponymous component of a large macromolecular complex that chaperones biogenesis of eukaryotic ribonucleoproteins and localizes to distinct membraneless organelles in both the nucleus and cytoplasm. SMN forms the oligomeric core of this complex, and missense mutations within its YG box domain are known to cause Spinal Muscular Atrophy (SMA). The SMN YG box utilizes a unique variant of the glycine zipper motif to form dimers, but the mechanism of higher-order oligomerization remains unknown. Here, we use a combination of molecular genetic, phylogenetic, biophysical, biochemical and computational approaches to show that formation of higher-order SMN oligomers depends on a set of YG box residues that are not involved in dimerization. Mutation of key residues within this new structural motif restricts assembly of SMN to dimers and causes locomotor dysfunction and viability defects in animal models.
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Affiliation(s)
- Kushol Gupta
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Ying Wen
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nisha S Ninan
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Amanda C Raimer
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert Sharp
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Ashlyn M Spring
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kathryn L Sarachan
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - Meghan C Johnson
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Gregory D Van Duyne
- Department of Biochemistry & Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19105-6059, USA
| | - A Gregory Matera
- Integrative Program for Biological & Genome Sciences, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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Swinehart W, Deutsch C, Sarachan KL, Luthra A, Bacusmo JM, de Crécy-Lagard V, Swairjo MA, Agris PF, Iwata-Reuyl D. Specificity in the biosynthesis of the universal tRNA nucleoside N6-threonylcarbamoyl adenosine (t 6A)-TsaD is the gatekeeper. RNA 2020; 26:1094-1103. [PMID: 32385138 PMCID: PMC7430679 DOI: 10.1261/rna.075747.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 05/03/2020] [Indexed: 06/11/2023]
Abstract
N6-threonylcarbamoyl adenosine (t6A) is a nucleoside modification found in all kingdoms of life at position 37 of tRNAs decoding ANN codons, which functions in part to restrict translation initiation to AUG and suppress frameshifting at tandem ANN codons. In Bacteria the proteins TsaB, TsaC (or C2), TsaD, and TsaE, comprise the biosynthetic apparatus responsible for t6A formation. TsaC(C2) and TsaD harbor the relevant active sites, with TsaC(C2) catalyzing the formation of the intermediate threonylcarbamoyladenosine monophosphate (TC-AMP) from ATP, threonine, and CO2, and TsaD catalyzing the transfer of the threonylcarbamoyl moiety from TC-AMP to A37 of substrate tRNAs. Several related modified nucleosides, including hydroxynorvalylcarbamoyl adenosine (hn6A), have been identified in select organisms, but nothing is known about their biosynthesis. To better understand the mechanism and structural constraints on t6A formation, and to determine if related modified nucleosides are formed via parallel biosynthetic pathways or the t6A pathway, we carried out biochemical and biophysical investigations of the t6A systems from E. coli and T. maritima to address these questions. Using kinetic assays of TsaC(C2), tRNA modification assays, and NMR, our data demonstrate that TsaC(C2) exhibit relaxed substrate specificity, producing a variety of TC-AMP analogs that can differ in both the identity of the amino acid and nucleotide component, whereas TsaD displays more stringent specificity, but efficiently produces hn6A in E. coli and T. maritima tRNA. Thus, in organisms that contain modifications such as hn6A in their tRNA, we conclude that their origin is due to formation via the t6A pathway.
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Affiliation(s)
- William Swinehart
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | - Christopher Deutsch
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
| | - Kathryn L Sarachan
- The RNA Institute, State University of New York, Albany, New York 12222, USA
| | - Amit Luthra
- Department of Chemistry and Biochemistry, and The Viral Information Institute, San Diego State University, San Diego, California 92182, USA
| | - Jo Marie Bacusmo
- Department of Microbiology and Cell Science, University of Florida, Gainsville, Florida 32611, USA
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainsville, Florida 32611, USA
| | - Manal A Swairjo
- Department of Chemistry and Biochemistry, and The Viral Information Institute, San Diego State University, San Diego, California 92182, USA
| | - Paul F Agris
- The RNA Institute, State University of New York, Albany, New York 12222, USA
| | - Dirk Iwata-Reuyl
- Department of Chemistry, Portland State University, Portland, Oregon 97201, USA
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Vangaveti S, Ranganathan S, Sarachan KL, Agris PF, Chen A, Cantara W. Understanding the Effect of Post Transcriptional Modifications in the Anticodon Stem Loop of E.coli tRNA Arginine. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Gupta K, Martin R, Sharp R, Sarachan KL, Ninan NS, Van Duyne GD. Oligomeric Properties of Survival Motor Neuron·Gemin2 Complexes. J Biol Chem 2015; 290:20185-99. [PMID: 26092730 PMCID: PMC4536428 DOI: 10.1074/jbc.m115.667279] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [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: 05/22/2015] [Revised: 06/18/2015] [Indexed: 12/29/2022] Open
Abstract
The survival motor neuron (SMN) protein forms the oligomeric core of a multiprotein complex required for the assembly of spliceosomal small nuclear ribonucleoproteins. Deletions and mutations in the SMN1 gene are associated with spinal muscular atrophy (SMA), a devastating neurodegenerative disease that is the leading heritable cause of infant mortality. Oligomerization of SMN is required for its function, and some SMA patient mutations disrupt the ability of SMN to self-associate. Here, we investigate the oligomeric nature of the SMN·Gemin2 complexes from humans and fission yeast (hSMN·Gemin2 and ySMN·Gemin2). We find that hSMN·Gemin2 forms oligomers spanning the dimer to octamer range. The YG box oligomerization domain of SMN is both necessary and sufficient to form these oligomers. ySMN·Gemin2 exists as a dimer-tetramer equilibrium with Kd = 1.0 ± 0.9 μM. A 1.9 Å crystal structure of the ySMN YG box confirms a high level of structural conservation with the human ortholog in this important region of SMN. Disulfide cross-linking experiments indicate that SMN tetramers are formed by self-association of stable, non-dissociating dimers. Thus, SMN tetramers do not form symmetric helical bundles such as those found in glycine zipper transmembrane oligomers. The dimer-tetramer nature of SMN complexes and the dimer of dimers organization of the SMN tetramer provide an important foundation for ongoing studies to understand the mechanism of SMN-assisted small nuclear ribonucleoprotein assembly and the underlying causes of SMA.
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Affiliation(s)
- Kushol Gupta
- From the Department of Biochemistry and Biophysics and
| | - Renee Martin
- From the Department of Biochemistry and Biophysics and the Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
| | - Robert Sharp
- From the Department of Biochemistry and Biophysics and
| | - Kathryn L Sarachan
- From the Department of Biochemistry and Biophysics and the Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
| | - Nisha S Ninan
- From the Department of Biochemistry and Biophysics and the Graduate Group in Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104-6059
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Hong S, Harris KA, Fanning KD, Sarachan KL, Frohlich KM, Agris PF. Evidence That Antibiotics Bind to Human Mitochondrial Ribosomal RNA Has Implications for Aminoglycoside Toxicity. J Biol Chem 2015; 290:19273-86. [PMID: 26060252 DOI: 10.1074/jbc.m115.655092] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Indexed: 12/11/2022] Open
Abstract
Aminoglycosides are a well known antibiotic family used to treat bacterial infections in humans and animals, but which can be toxic. By binding to the decoding site of helix44 of the small subunit RNA of the bacterial ribosome, the aminoglycoside antibiotics inhibit protein synthesis, cause misreading, or obstruct peptidyl-tRNA translocation. Although aminoglycosides bind helix69 of the bacterial large subunit RNA as well, little is known about their interaction with the homologous human helix69. To probe the role this binding event plays in toxicity, changes to thermal stability, base stacking, and conformation upon aminoglycoside binding to the human cytoplasmic helix69 were compared with those of the human mitochondrial and Escherichia coli helix69. Surprisingly, binding of gentamicin and kanamycin A to the chemically synthesized terminal hairpins of the human cytoplasmic, human mitochondrial, and E. coli helix69 revealed similar dissociation constants (1.3-1.7 and 4.0-5.4 μM, respectively). In addition, aminoglycoside binding enhanced conformational stability of the human mitochondrial helix69 by increasing base stacking. Proton one-dimensional and two-dimensional NMR suggested significant and specific conformational changes of human mitochondrial and E. coli helix69 upon aminoglycoside binding, as compared with human cytoplasmic helix69. The conformational changes and similar aminoglycoside binding affinities observed for human mitochondrial helix69 and E. coli helix69, as well as the increase in structural stability shown for the former, suggest that this binding event is important to understanding aminoglycoside toxicity.
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Affiliation(s)
- Seoyeon Hong
- From The RNA Institute and the Department of Biological Sciences, University at Albany, Albany, New York 12222
| | - Kimberly A Harris
- From The RNA Institute and the Department of Biological Sciences, University at Albany, Albany, New York 12222
| | - Kathryn D Fanning
- From The RNA Institute and the Department of Biological Sciences, University at Albany, Albany, New York 12222
| | - Kathryn L Sarachan
- From The RNA Institute and the Department of Biological Sciences, University at Albany, Albany, New York 12222
| | - Kyla M Frohlich
- From The RNA Institute and the Department of Biological Sciences, University at Albany, Albany, New York 12222
| | - Paul F Agris
- From The RNA Institute and the Department of Biological Sciences, University at Albany, Albany, New York 12222
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Harris KA, Bobay BG, Sarachan KL, Sims AF, Bilbille Y, Deutsch C, Iwata-Reuyl D, Agris PF. NMR-based Structural Analysis of Threonylcarbamoyl-AMP Synthase and Its Substrate Interactions. J Biol Chem 2015; 290:20032-43. [PMID: 26060251 DOI: 10.1074/jbc.m114.631242] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Indexed: 11/06/2022] Open
Abstract
The hypermodified nucleoside N(6)-threonylcarbamoyladenosine (t(6)A37) is present in many distinct tRNA species and has been found in organisms in all domains of life. This post-transcriptional modification enhances translation fidelity by stabilizing the anticodon/codon interaction in the ribosomal decoding site. The biosynthetic pathway of t(6)A37 is complex and not well understood. In bacteria, the following four proteins have been discovered to be both required and sufficient for t(6)A37 modification: TsaC, TsaD, TsaB, and TsaE. Of these, TsaC and TsaD are members of universally conserved protein families. Although TsaC has been shown to catalyze the formation of L-threonylcarbamoyl-AMP, a key intermediate in the biosynthesis of t(6)A37, the details of the enzymatic mechanism remain unsolved. Therefore, the solution structure of Escherichia coli TsaC was characterized by NMR to further study the interactions with ATP and L-threonine, both substrates of TsaC in the biosynthesis of L-threonylcarbamoyl-AMP. Several conserved amino acids were identified that create a hydrophobic binding pocket for the adenine of ATP. Additionally, two residues were found to interact with L-threonine. Both binding sites are located in a deep cavity at the center of the protein. Models derived from the NMR data and molecular modeling reveal several sites with considerable conformational flexibility in TsaC that may be important for L-threonine recognition, ATP activation, and/or protein/protein interactions. These observations further the understanding of the enzymatic reaction catalyzed by TsaC, a threonylcarbamoyl-AMP synthase, and provide structure-based insight into the mechanism of t(6)A37 biosynthesis.
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Affiliation(s)
- Kimberly A Harris
- From the Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695, The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, Albany, New York 12222, and
| | - Benjamin G Bobay
- From the Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Kathryn L Sarachan
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, Albany, New York 12222, and
| | - Alexis F Sims
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, Albany, New York 12222, and
| | - Yann Bilbille
- From the Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Christopher Deutsch
- the Department of Chemistry, Portland State University, Portland, Oregon 97207
| | - Dirk Iwata-Reuyl
- the Department of Chemistry, Portland State University, Portland, Oregon 97207
| | - Paul F Agris
- The RNA Institute, Departments of Biological Sciences and Chemistry, University at Albany, Albany, New York 12222, and
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Sarachan KL, Cantara WA, Spears JL, Dimirci H, Murphy FV, Ranganathan S, Chen A, Agris PF. 107 Modifications modulate anticodon loop dynamics and codon recognition in E. colitRNA Arg1,2. J Biomol Struct Dyn 2015. [DOI: 10.1080/07391102.2015.1032669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Sarachan KL, Curtis JE, Krueger S. Small-angle scattering contrast calculator for protein and nucleic acid complexes in solution. J Appl Crystallogr 2013. [DOI: 10.1107/s0021889813025727] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Small-angle neutron scattering (SANS) with contrast variation can provide useful information about the structure and disposition of two or more chemically distinct components within a complex. TheSASSIE Contrast Calculator(SCC) is a new software tool designed to assist in planning SANS experiments with contrast variation on protein and nucleic acid complexes. On the basis of the primary sequence and deuteration level of each protein or nucleic acid component, theSCCcalculates and plotsI(0), contrast and scattering length densities; since SANS experiments often complement small-angle X-ray scattering studies, the program provides both neutron and X-ray parameters. TheSCCis run as an integrated component ofSASSIE[Curtis, Raghunandan, Nanda & Krueger (2012).Comput. Phys. Commun.183, 382–389], a software suite for atomistic modeling of ensembles of structures consistent with scattering data.
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Sarachan KL, Clark N, Krueger S, Curtis JE. Coarse-Grained Atomistic Models from Affine Transformations of Geometric Shapes Applied to Small-Angle Scattering. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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