1
|
The Interaction between the Ribosomal Stalk Proteins and Translation Initiation Factor 5B Promotes Translation Initiation. Mol Cell Biol 2018; 38:MCB.00067-18. [PMID: 29844065 DOI: 10.1128/mcb.00067-18] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 05/14/2018] [Indexed: 01/01/2023] Open
Abstract
Ribosomal stalk proteins recruit translation elongation GTPases to the factor-binding center of the ribosome. Initiation factor 5B (eIF5B in eukaryotes and aIF5B in archaea) is a universally conserved GTPase that promotes the joining of the large and small ribosomal subunits during translation initiation. Here we show that aIF5B binds to the C-terminal tail of the stalk protein. In the cocrystal structure, the interaction occurs between the hydrophobic amino acids of the stalk C-terminal tail and a small hydrophobic pocket on the surface of the GTP-binding domain (domain I) of aIF5B. A substitution mutation altering the hydrophobic pocket of yeast eIF5B resulted in a marked reduction in ribosome-dependent eIF5B GTPase activity in vitro In yeast cells, the eIF5B mutation affected growth and impaired GCN4 expression during amino acid starvation via a defect in start site selection for the first upstream open reading frame in GCN4 mRNA, as observed with the eIF5B deletion mutant. The deletion of two of the four stalk proteins diminished polyribosome levels (indicating defective translation initiation) and starvation-induced GCN4 expression, both of which were suppressible by eIF5B overexpression. Thus, the mutual interaction between a/eIF5B and the ribosomal stalk plays an important role in subunit joining during translation initiation in vivo.
Collapse
|
2
|
Pagano GJ, King RS, Martin LM, Hufnagel LA. The unique N-terminal insert in the ribosomal protein, phosphoprotein P0, of Tetrahymena thermophila: Bioinformatic evidence for an interaction with 26S rRNA. Proteins 2015; 83:1078-90. [PMID: 25820769 DOI: 10.1002/prot.24800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 02/27/2015] [Accepted: 03/20/2015] [Indexed: 11/11/2022]
Abstract
Phosphoprotein P0 (P0) is part of the stalk complex of the eukaryotic large ribosomal subunit necessary for recruiting elongation factors. While the P0 sequence is highly conserved, our group noted a 15-16 residue insert exclusive to the P0s of ciliated protists, including Tetrahymena thermophila. We hypothesized that this insert may have a function unique in ciliated protists, such as stalk regulation via phosphorylation of the insert. Almost no mention of this insert exists in the literature, and although the T. thermophila ribosome has been crystallized, there is limited structural data for Tetrahymena's P0 (TtP0) and its insert. To investigate the structure and function of the TtP0 insert, we performed in silico analyses. The TtP0 sequence was scanned with phosphorylation site prediction tools to detect the likelihood of phosphorylation in the insert. TtP0's sequence was also used to produce a homology model of the N-terminal domain of TtP0, including the insert. When the insert was modeled in the context of the 26S rRNA, it associated with a region identified as expansion segment 7B (ES7B), suggesting a potential functional interaction between ES7B and the insert in T. thermophila. We were not able to obtain sufficient data to determine whether a similar relationship exists in other ciliated protists. This study lays the groundwork for future experimental studies to verify the presence of TtP0 insert/ES7 interactions in Tetrahymena, and to explore their functional significance during protein synthesis.
Collapse
Affiliation(s)
- Giovanni J Pagano
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, 02881
| | - Roberta S King
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, Rhode Island, 02881
| | - Lenore M Martin
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, 02881
| | - Linda A Hufnagel
- Department of Cell and Molecular Biology, University of Rhode Island, Kingston, Rhode Island, 02881
| |
Collapse
|
3
|
Ito K, Honda T, Suzuki T, Miyoshi T, Murakami R, Yao M, Uchiumi T. Molecular insights into the interaction of the ribosomal stalk protein with elongation factor 1α. Nucleic Acids Res 2014; 42:14042-52. [PMID: 25428348 PMCID: PMC4267659 DOI: 10.1093/nar/gku1248] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In all organisms, the large ribosomal subunit contains multiple copies of a flexible protein, the so-called ‘stalk’. The C-terminal domain (CTD) of the stalk interacts directly with the translational GTPase factors, and this interaction is required for factor-dependent activity on the ribosome. Here we have determined the structure of a complex of the CTD of the archaeal stalk protein aP1 and the GDP-bound archaeal elongation factor aEF1α at 2.3 Å resolution. The structure showed that the CTD of aP1 formed a long extended α-helix, which bound to a cleft between domains 1 and 3 of aEF1α, and bridged these domains. This binding between the CTD of aP1 and the aEF1α•GDP complex was formed mainly by hydrophobic interactions. The docking analysis showed that the CTD of aP1 can bind to aEF1α•GDP located on the ribosome. An additional biochemical assay demonstrated that the CTD of aP1 also bound to the aEF1α•GTP•aminoacyl-tRNA complex. These results suggest that the CTD of aP1 interacts with aEF1α at various stages in translation. Furthermore, phylogenetic perspectives and functional analyses suggested that the eukaryotic stalk protein also interacts directly with domains 1 and 3 of eEF1α, in a manner similar to the interaction of archaeal aP1 with aEF1α.
Collapse
Affiliation(s)
- Kosuke Ito
- Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Takayoshi Honda
- Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Takahiro Suzuki
- Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Tomohiro Miyoshi
- Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Ryo Murakami
- Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| | - Min Yao
- Faculty of Advanced Life Science, Hokkaido University, Kita-ku, Kita-10, Nishi-8, Sapporo 060-0810, Japan
| | - Toshio Uchiumi
- Department of Biology, Faculty of Science, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan
| |
Collapse
|
4
|
Ayub MJ, Nyambega B, Simonetti L, Duffy T, Longhi SA, Gómez KA, Hoebeke J, Levin MJ, Smulski CR. Selective blockade of trypanosomatid protein synthesis by a recombinant antibody anti-Trypanosoma cruzi P2β protein. PLoS One 2012; 7:e36233. [PMID: 22570698 PMCID: PMC3343115 DOI: 10.1371/journal.pone.0036233] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 03/28/2012] [Indexed: 11/18/2022] Open
Abstract
The ribosomal P proteins are located on the stalk of the ribosomal large subunit and play a critical role during the elongation step of protein synthesis. The single chain recombinant antibody C5 (scFv C5) directed against the C-terminal region of the Trypanosoma cruzi P2β protein (TcP2β) recognizes the conserved C-terminal end of all T. cruzi ribosomal P proteins. Although this region is highly conserved among different species, surface plasmon resonance analysis showed that the scFv C5 possesses very low affinity for the corresponding mammalian epitope, despite having only one single amino-acid change. Crystallographic analysis, in silico modelization and NMR assays support the analysis, increasing our understanding on the structural basis of epitope specificity. In vitro protein synthesis experiments showed that scFv C5 was able to specifically block translation by T. cruzi and Crithidia fasciculata ribosomes, but virtually had no effect on Rattus norvegicus ribosomes. Therefore, we used the scFv C5 coding sequence to make inducible intrabodies in Trypanosoma brucei. Transgenic parasites showed a strong decrease in their growth rate after induction. These results strengthen the importance of the P protein C terminal regions for ribosomal translation activity and suggest that trypanosomatid ribosomal P proteins could be a possible target for selective therapeutic agents that could be derived from structural analysis of the scFv C5 antibody paratope.
Collapse
Affiliation(s)
- Maximiliano Juri Ayub
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
Archaeal ribosomal stalk protein interacts with translation factors in a nucleotide-independent manner via its conserved C terminus. Proc Natl Acad Sci U S A 2012; 109:3748-53. [PMID: 22355137 DOI: 10.1073/pnas.1112934109] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Protein synthesis on the ribosome requires translational GTPase factors to bind to the ribosome in the GTP-bound form, take individual actions that are coupled with GTP hydrolysis, and dissociate, usually in the GDP-bound form. The multiple copies of the flexible ribosomal stalk protein play an important role in these processes. Using biochemical approaches and the stalk protein from a hyperthermophilic archaeon, Pyrococcus horikoshii, we here provide evidence that the conserved C terminus of the stalk protein aP1 binds directly to domain I of the elongation factor aEF-2, irrespective of whether aEF-2 is bound to GTP or GDP. Site-directed mutagenesis revealed that four hydrophobic amino acids at the C terminus of aP1, Leu-100, 103, 106, and Phe-107, are crucial for the direct binding. P1 was also found to bind to the initiation factor aIF5B, as well as aEF-1α, but not aIF2γ, via its C terminus. Moreover, analytical ultracentrifugation and gel mobility shift analyses showed that a heptameric complex of aP1 and aP0, aP0(aP1)(2)(aP1)(2)(aP1)(2), can bind multiple aEF-2 molecules simultaneously, which suggests that individual copies of the stalk protein are accessible to the factor. The functional significance of the C terminus of the stalk protein was also shown using the eukaryotic proteins P1/P2 and P0. It is likely that the conserved C terminus of the stalk proteins of archaea and eukaryotes can bind to translation factors both before and after GTP hydrolysis. This consistent binding ability of the stalk protein may contribute to maintaining high concentrations of translation factors around the ribosome, thus promoting translational efficiency.
Collapse
|
6
|
Gangwar RS, Shil P, Sapkal GN, Khan SA, Gore MM. Induction of virus-specific neutralizing immune response against West Nile and Japanese encephalitis viruses by chimeric peptides representing T-helper and B-cell epitopes. Virus Res 2012; 163:40-50. [DOI: 10.1016/j.virusres.2011.08.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/08/2011] [Accepted: 08/15/2011] [Indexed: 02/03/2023]
|
7
|
Pizarro JC, Boulot G, Bentley GA, Gómez KA, Hoebeke J, Hontebeyrie M, Levin MJ, Smulski CR. Crystal structure of the complex mAb 17.2 and the C-terminal region of Trypanosoma cruzi P2β protein: implications in cross-reactivity. PLoS Negl Trop Dis 2011; 5:e1375. [PMID: 22069505 PMCID: PMC3206007 DOI: 10.1371/journal.pntd.0001375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Accepted: 09/11/2011] [Indexed: 01/07/2023] Open
Abstract
Patients with Chronic Chagas' Heart Disease possess high levels of antibodies against the carboxyl-terminal end of the ribosomal P2ß protein of Trypanosoma cruzi (TcP2ß). These antibodies, as well as the murine monoclonal antibody (mAb) 17.2, recognize the last 13 amino acids of TcP2ß (called the R13 epitope: EEEDDDMGFGLFD) and are able to cross-react with, and stimulate, the ß1 adrenergic receptor (ß1-AR). Indeed, the mAb 17.2 was able to specifically detect human β1-AR, stably transfected into HEK cells, by flow cytometry and to induce repolarisation abnormalities and first degree atrioventricular conduction block after passive transfer to naïve mice. To study the structural basis of this cross-reactivity, we determined the crystal structure of the Fab region of the mAb 17.2 alone at 2.31 Å resolution and in complex with the R13 peptide at 1.89 Å resolution. We identified as key contact residues on R13 peptide Glu3, Asp6 and Phe9 as was previously shown by alanine scanning. Additionally, we generated a model of human β1-AR to elucidate the interaction with anti-R13 antibodies. These data provide an understanding of the molecular basis of cross-reactive antibodies induced by chronic infection with Trypanosoma cruzi.
Collapse
MESH Headings
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/metabolism
- Antibodies, Protozoan/chemistry
- Antibodies, Protozoan/immunology
- Antibodies, Protozoan/metabolism
- Cross Reactions
- Crystallography, X-Ray
- Female
- Humans
- Immunoglobulin Fab Fragments/chemistry
- Immunoglobulin Fab Fragments/immunology
- Immunoglobulin Fab Fragments/metabolism
- Mice
- Mice, Inbred BALB C
- Models, Molecular
- Phosphoproteins/chemistry
- Phosphoproteins/immunology
- Phosphoproteins/metabolism
- Protein Binding
- Protein Structure, Quaternary
- Receptors, Adrenergic, beta-1/immunology
- Receptors, Adrenergic, beta-1/metabolism
- Ribosomal Proteins/chemistry
- Ribosomal Proteins/immunology
- Ribosomal Proteins/metabolism
- Trypanosoma cruzi/chemistry
Collapse
Affiliation(s)
- Juan Carlos Pizarro
- Unité d'Immunologie Structurale, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 2185, Paris, France
| | - Ginette Boulot
- Unité d'Immunologie Structurale, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 2185, Paris, France
| | - Graham A. Bentley
- Unité d'Immunologie Structurale, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 2185, Paris, France
| | - Karina A. Gómez
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
| | | | | | - Mariano J. Levin
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
| | - Cristian R. Smulski
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, INGEBI-CONICET, Buenos Aires, Argentina
- UPR9021 du CNRS, Strasbourg, France
- * E-mail:
| |
Collapse
|
8
|
Denadai ÂM, Santoro MM, Texeira AV, Sinisterra RD. New insights regarding the cyclodextrin/AAS self-assembly: A molar ratio dependent system. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2010. [DOI: 10.1016/j.msec.2009.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
9
|
Gadermaier G, Jahn-Schmid B, Vogel L, Egger M, Himly M, Briza P, Ebner C, Vieths S, Bohle B, Ferreira F. Targeting the cysteine-stabilized fold of Art v 1 for immunotherapy of Artemisia pollen allergy. Mol Immunol 2010; 47:1292-8. [DOI: 10.1016/j.molimm.2009.11.029] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 11/22/2009] [Accepted: 11/24/2009] [Indexed: 10/20/2022]
|
10
|
Martín OA, Villegas ME, Aguilar CF. Three-dimensional studies of pathogenic peptides from the c-terminal of Trypanosoma cruzi ribosomal P proteins and their interaction with a monoclonal antibody structural model. PMC BIOPHYSICS 2009; 2:4. [PMID: 19473527 PMCID: PMC2704175 DOI: 10.1186/1757-5036-2-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Accepted: 05/27/2009] [Indexed: 11/10/2022]
Abstract
The acidic C-terminal peptides from Trypanosoma cruzi ribosomal P proteins are the major target of the antibody response in patients suffering Chagas chronic heart disease. It has been proposed that the disease is triggered by the cross-reaction of these antibodies with the second extra cellular loop of the beta1-adrenoreceptor, brought about by the molecular mimicry between the acidic C-terminal peptides and the receptor's loop. To improve the understanding of the structural basis of the autoimmune response against heart receptors, the 3-dimensional structure of the C-terminal peptides of Trypanosoma cruzi ribosomal proteins P0 (EDDDDDFGMGALF) and P2beta (EEEDDDMGFGLFD) were solved using the Electrostaticaly Driven MonteCarlo method. Their structures were compared with the second extra-cellular loop of our homology model of human rhodopsin and the existing experimental NMR structures of the C-terminal peptides from human P0 (EESDDDMGFGLFD) and from Leishmania braziliensis P0 (EEADDDMGFGLFD). Docking of Trypanosoma cruzi peptides P0, P2beta and human rhodopsin loop into our anti-P2beta monoclonal antibody homology model allowed to explore their interactions.The solution structure of peptides P0 and P2beta can be briefly described as a bend. Although the global conformations of the peptides are not identical they shared a common region of four residues (3 to 6) that have a similar structure. The structural alignment of the five peptides also showed a surprising conformational similarity for the same residues. The antibody model and docking studies revealed a most remarkable feature in the active site, a positively charged, narrow and deep cavity where the acidic residues 3 to 6 were accommodated. These results suggest that the most important elements in the molecular peptide recognition by the antibody may be the shape of the loop and the presence of negative charges in positions 3-5 (P0, P2beta) or a negative charge in position 4 (rhodopsin loop). This work describes clearly the interactions of the structural elements involved in the autoimmune mechanism of anti-P auto-antibodies cross-reaction and stimulation of the beta1-adrenoreceptor and the visual pigment rhodopsin. Results from this study could lead eventually to the development of treatments to abolish receptor mediated symptoms in Chagas. PACS code: 87.15.-v.
Collapse
Affiliation(s)
- Osvaldo A Martín
- Instituto de Matemática Aplicada de San Luis, CONICET, Ejército de los Andes 950, primer piso, 5700, San Luis, Argentina.
| | | | | |
Collapse
|
11
|
Grela P, Bernadó P, Svergun D, Kwiatowski J, Abramczyk D, Grankowski N, Tchórzewski M. Structural Relationships Among the Ribosomal Stalk Proteins from the Three Domains of Life. J Mol Evol 2008; 67:154-67. [DOI: 10.1007/s00239-008-9132-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 05/10/2008] [Accepted: 06/09/2008] [Indexed: 11/30/2022]
|
12
|
Kessenbrock K, Fritzler MJ, Groves M, Eissfeller P, von Mühlen CA, Höpfl P, Mahler M. Diverse humoral autoimmunity to the ribosomal P proteins in systemic lupus erythematosus and hepatitis C virus infection. J Mol Med (Berl) 2007; 85:953-9. [PMID: 17668158 DOI: 10.1007/s00109-007-0239-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 06/08/2007] [Accepted: 06/11/2007] [Indexed: 11/28/2022]
Abstract
Autoantibodies to the three ribosomal P proteins (Rib-P) are specifically found in 10% to 40% of systemic lupus erythematosus (SLE) patients. Most anti-Rib-P autoantibodies bind to a C-terminal epitope shared by all three Rib-P proteins P0, P1 and P2. In the present study, we shed more light on the humoral autoimmune response to the Rib-P antigen as it occurs in autoimmunity and infectious disease. In a mutational analysis of the major C-terminal epitope, we verified the key role of phenylalanine residues Phe ( 111 ) and Phe ( 114 ) for binding of most anti-Rib-P serum autoantibodies present in SLE sera (n = 28). By nuclear magnetic resonance (NMR) investigation of a peptide comprising the C-terminal 22 amino acids, we observed hallmarks for alpha-helical secondary structure of the Rib-P epitope core (GFGLFD). Based on NMR data and on SPOT epitope analysis, we propose a structural model of the Rib-P major epitope, which displays Phe ( 111 ) and Phe ( 114 ) on one side of the helix. Apart from that, two sera from the hepatitis C virus (HCV) control group (n = 68) were found to contain antibodies specific for P2, but not for the other Rib-P proteins. Using a SPOT peptide array scanning the P2 amino acid sequence, we identified reactivity with two distinct epitopes (residues 21-35 and 41-55 of Rib-P2) shared by both HCV sera. We conclude that anti-Rib-P autoreactivity occurs in SLE, Chagas' disease (CD) and-as firstly described here-during HCV infection. Anti-Rib-P reactivity in SLE sera primarily depends on Phe ( 111 ) and Phe ( 114 ) of the alpha-helical C-terminal epitope. In contrast, anti-Rib-P autoantibodies in HCV infection mainly recognize epitopes within the N-terminal half of ribosomal P2.
Collapse
|
13
|
Grela P, Helgstrand M, Krokowski D, Boguszewska A, Svergun D, Liljas A, Bernadó P, Grankowski N, Akke M, Tchórzewski M. Structural Characterization of the Ribosomal P1A−P2B Protein Dimer by Small-Angle X-ray Scattering and NMR Spectroscopy. Biochemistry 2007; 46:1988-98. [PMID: 17261029 DOI: 10.1021/bi0616450] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The five ribosomal P-proteins, denoted P0-(P1-P2)2, constitute the stalk structure of the large subunit of eukaryotic ribosomes. In the yeast Saccharomyces cerevisiae, the group of P1 and P2 proteins is differentiated into subgroups that form two separate P1A-P2B and P1B-P2A heterodimers on the stalk. So far, structural studies on the P-proteins have not yielded any satisfactory information using either X-ray crystallography or NMR spectroscopy, and the structures of the ribosomal stalk and its individual constituents remain obscure. Here we outline a first, coarse-grained view of the P1A-P2B solution structure obtained by a combination of small-angle X-ray scattering and heteronuclear NMR spectroscopy. The complex has an elongated shape with a length of 10 nm and a cross section of approximately 2.5 nm. 15N NMR relaxation measurements establish that roughly 30% of the residues are present in highly flexible segments, which belong primarily to the linker region and the C-terminal part of the polypeptide chain. Secondary structure predictions and NMR chemical shift analysis, together with previous results from CD spectroscopy, indicate that the structured regions involve alpha-helices. NMR relaxation data further suggest that several helices are arranged in a nearly parallel or antiparallel topology. These results provide the first structural comparison between eukaryotic P1 and P2 proteins and the prokaryotic L12 counterpart, revealing considerable differences in their overall shapes, despite similar functional roles and similar oligomeric arrangements. These results present for the first time a view of the structure of the eukaryotic stalk constituents, which is the only domain of the eukaryotic ribosome that has escaped successful structural characterization.
Collapse
Affiliation(s)
- Przemysłw Grela
- Department of Molecular Biology, Institute of Microbiology and Biotechnology, Maria Curie-Skłdowska University, Akademicka 19, 20-033 Lublin, Poland
| | | | | | | | | | | | | | | | | | | |
Collapse
|