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Dutta A, Szekely Z, Guven H, Li XP, McLaughlin JE, Tumer NE. A fluorescence anisotropy-based competition assay to identify inhibitors against ricin and Shiga toxin ribosome interactions. Anal Biochem 2024; 692:115580. [PMID: 38825159 DOI: 10.1016/j.ab.2024.115580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 05/16/2024] [Accepted: 05/24/2024] [Indexed: 06/04/2024]
Abstract
Ricin is one of the most toxic substances known and a type B biothreat agent. Shiga toxins (Stxs) produced by E. coli (STEC) and Shigella dysenteriae are foodborne pathogens. There is no effective therapy against ricin or STEC and there is an urgent need for inhibitors. Ricin toxin A subunit (RTA) and A1 subunit of Stx2a (Stx2A1) bind to the C-terminal domain (CTD) of the ribosomal P-stalk proteins to depurinate the sarcin/ricin loop. Modulation of toxin-ribosome interactions has not been explored as a strategy for inhibition. Therefore, development of assays that detect inhibitors targeting toxin-ribosome interactions remains a critical need. Here we describe a fluorescence anisotropy (FA)-based competitive binding assay using a BODIPY-TMR labeled 11-mer peptide (P11) derived from the P-stalk CTD to measure the binding affinity of peptides ranging from 3 to 11 amino acids for the P-stalk pocket of RTA and Stx2A1. Comparison of the affinity with the surface plasmon resonance (SPR) assay indicated that although the rank order was the same by both methods, the FA assay could differentiate better between peptides that show nonspecific interactions by SPR. The FA assay detects only interactions that compete with the labeled P11 and can validate inhibitor specificity and mechanism of action.
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Affiliation(s)
- Arkajyoti Dutta
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, NJ, 08901, USA
| | - Zoltan Szekely
- Molecular Design and Synthesis Core, Rutgers University Biomolecular Innovations Cores, Office for Research, Rutgers University, 610 Taylor Rd, Piscataway, NJ, 08854, USA
| | - Hakan Guven
- Molecular Design and Synthesis Core, Rutgers University Biomolecular Innovations Cores, Office for Research, Rutgers University, 610 Taylor Rd, Piscataway, NJ, 08854, USA
| | - Xiao-Ping Li
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, NJ, 08901, USA.
| | - John E McLaughlin
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, NJ, 08901, USA
| | - Nilgun E Tumer
- Molecular Design and Synthesis Core, Rutgers University Biomolecular Innovations Cores, Office for Research, Rutgers University, 610 Taylor Rd, Piscataway, NJ, 08854, USA.
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2
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Rudolph MJ, Tsymbal AM, Dutta A, Davis SA, Algava B, Roberge JY, Tumer NE, Li XP. Fragment Screening to Identify Inhibitors Targeting Ribosome Binding of Shiga Toxin 2. ACS Infect Dis 2024. [PMID: 38873918 DOI: 10.1021/acsinfecdis.4c00224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
Shiga toxins are the main virulence factors of Shiga toxin producing E. coli (STEC) and S. dysenteriae. There is no effective therapy to counter the disease caused by these toxins. The A1 subunits of Shiga toxins bind the C-termini of ribosomal P-stalk proteins to depurinate the sarcin/ricin loop. The ribosome binding site of Shiga toxin 2 has not been targeted by small molecules. We screened a fragment library against the A1 subunit of Shiga toxin 2 (Stx2A1) and identified a fragment, BTB13086, which bound at the ribosome binding site and mimicked the binding mode of the P-stalk proteins. We synthesized analogs of BTB13086 and identified a series of molecules with similar affinity and inhibitory activity. These are the first compounds that bind at the ribosome binding site of Stx2A1 and inhibit activity. These compounds hold great promise for further inhibitor development against STEC infection.
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Affiliation(s)
- Michael J Rudolph
- New York Structural Biology Center, 89 Convent Ave, New York, New York 10027, United States
| | - Anastasiia M Tsymbal
- Molecular Design and Synthesis Core, Rutgers University Biomolecular Innovations Cores, Office for Research, Rutgers University, 610 Taylor Rd, Piscataway, New Jersey 08854, United States
| | - Arkajyoti Dutta
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
| | - Simon A Davis
- New York Structural Biology Center, 89 Convent Ave, New York, New York 10027, United States
| | - Benjamin Algava
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
| | - Jacques Y Roberge
- Molecular Design and Synthesis Core, Rutgers University Biomolecular Innovations Cores, Office for Research, Rutgers University, 610 Taylor Rd, Piscataway, New Jersey 08854, United States
| | - Nilgun E Tumer
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
| | - Xiao-Ping Li
- Department of Plant Biology, Rutgers, The State University of New Jersey, 59 Dudley Road, New Brunswick, New Jersey 08901, United States
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Hemmings SMJ, Swart P, Womersely JS, Ovenden ES, van den Heuvel LL, McGregor NW, Meier S, Bardien S, Abrahams S, Tromp G, Emsley R, Carr J, Seedat S. RNA-seq analysis of gene expression profiles in posttraumatic stress disorder, Parkinson's disease and schizophrenia identifies roles for common and distinct biological pathways. DISCOVER MENTAL HEALTH 2022; 2:6. [PMID: 37861850 PMCID: PMC10501040 DOI: 10.1007/s44192-022-00009-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/14/2022] [Indexed: 10/21/2023]
Abstract
Evidence suggests that shared pathophysiological mechanisms in neuropsychiatric disorders (NPDs) may contribute to risk and resilience. We used single-gene and network-level transcriptomic approaches to investigate shared and disorder-specific processes underlying posttraumatic stress disorder (PTSD), Parkinson's disease (PD) and schizophrenia in a South African sample. RNA-seq was performed on blood obtained from cases and controls from each cohort. Gene expression and weighted gene correlation network analyses (WGCNA) were performed using DESeq2 and CEMiTool, respectively. Significant differences in gene expression were limited to the PTSD cohort. However, WGCNA implicated, amongst others, ribosomal expression, inflammation and ubiquitination as key players in the NPDs under investigation. Differential expression in ribosomal-related pathways was observed in the PTSD and PD cohorts, and focal adhesion and extracellular matrix pathways were implicated in PD and schizophrenia. We propose that, despite different phenotypic presentations, core transdiagnostic mechanisms may play important roles in the molecular aetiology of NPDs.
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Affiliation(s)
- Sian M J Hemmings
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa.
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa.
| | - Patricia Swart
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
| | - Jacqueline S Womersely
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
| | - Ellen S Ovenden
- Systems Genetics Working Group, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Leigh L van den Heuvel
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
| | - Nathaniel W McGregor
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa
- Systems Genetics Working Group, Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Stuart Meier
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, Cape Town, South Africa
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
- South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
- South African Tuberculosis Bioinformatics Initiative, Stellenbosch University, Cape Town, South Africa
| | - Soraya Bardien
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, Cape Town, South Africa
| | - Shameemah Abrahams
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, Cape Town, South Africa
| | - Gerard Tromp
- Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Stellenbosch University, Cape Town, South Africa
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
- South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Cape Town, South Africa
- South African Tuberculosis Bioinformatics Initiative, Stellenbosch University, Cape Town, South Africa
- Centre for Bioinformatics and Computational Biology, Stellenbosch University, Stellenbosch, South Africa
| | - Robin Emsley
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa
| | - Jonathan Carr
- Division of Neurology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Soraya Seedat
- Department of Psychiatry, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 241, Cape Town, 8000, South Africa
- South African Medical Research Council/Stellenbosch University Genomics of Brain Disorders Research Unit, Stellenbosch University, Cape Town, South Africa
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Horbowicz-Drożdżal P, Kamel K, Kmiecik S, Borkiewicz L, Tumer NE, Shaw PC, Tchórzewski M, Grela P. Phosphorylation of the conserved C-terminal domain of ribosomal P-proteins impairs the mode of interaction with plant toxins. FEBS Lett 2021; 595:2221-2236. [PMID: 34328639 DOI: 10.1002/1873-3468.14170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/14/2021] [Accepted: 07/21/2021] [Indexed: 11/12/2022]
Abstract
The ribosome is subjected to post-translational modifications, including phosphorylation, that affect its biological activity. Among ribosomal elements, the P-proteins undergo phosphorylation within the C terminus, the element which interacts with trGTPases or ribosome-inactivating proteins (RIPs); however, the role of phosphorylation has never been elucidated. Here, we probed the function of phosphorylation on the interaction of P-proteins with RIPs using the ribosomal P1-P2 dimer. We determined the kinetic parameters of the interaction with the toxins using biolayer interferometry and microscale thermophoresis. The results present the first mechanistic insight into the function of P-protein phosphorylation, showing that introduction of a negative charge into the C terminus of P1-P2 proteins promotes α-helix formation and decreases the affinity of the P-proteins for the RIPs.
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Affiliation(s)
- Patrycja Horbowicz-Drożdżal
- Department of Molecular Biology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
| | - Karol Kamel
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznań, Poland
| | - Sebastian Kmiecik
- Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Poland
| | - Lidia Borkiewicz
- Department of Biochemistry and Molecular Biology, Medical University of Lublin, Poland
| | - Nilgun E Tumer
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ, USA
| | - Pang-Chui Shaw
- School of Life Sciences, The Chinese University of Hong Kong, China
| | - Marek Tchórzewski
- Department of Molecular Biology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
| | - Przemysław Grela
- Department of Molecular Biology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
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5
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Choi MY, FitzPatrick RD, Buhler K, Mahler M, Fritzler MJ. A review and meta-analysis of anti-ribosomal P autoantibodies in systemic lupus erythematosus. Autoimmun Rev 2020; 19:102463. [PMID: 31927088 DOI: 10.1016/j.autrev.2020.102463] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 09/08/2019] [Indexed: 12/11/2022]
Abstract
The discovery of autoantibodies to ribosomal proteins (anti-RibP) dates back more than fifty years when antibodies to ribosomes were identified in systemic lupus erythematosus (SLE) sera. Over the years, anti-RibP autoantibodies have been the subject of extensive study and became known as a highly specific biomarker for the diagnosis of SLE and were associated with neuropsychiatric SLE (NPSLE), lupus nephritis (LN) and hepatitis (LH). As demonstrated by studies on cultured human cells and of murine models, there is evidence to suggest that anti-RibP may have a pathogenic role in LN and NPSLE. Despite a wealth of evidence, in comparison to other SLE autoantibodies such as anti-Sm and anti-dsDNA, anti-RibP has not been included in classification criteria for SLE. A significant challenge is the variability of assays used to detect anti-RibP, including the antigens and diagnostic platforms employed. This may account for the marked variation in frequencies (10-47%) in SLE and its association with clinical and demographic features reported in SLE cohorts. We performed a systematic literature review and meta-analysis to help clarify its prevalence, various clinical and serological associations in SLE based on the different RibP antigens and assay platforms used.
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Affiliation(s)
- May Y Choi
- Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB T2N4N1, Canada
| | - Rachael D FitzPatrick
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Katherine Buhler
- Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB T2N4N1, Canada
| | - Michael Mahler
- Inova Diagnostics, San Diego, CA, United States of America
| | - Marvin J Fritzler
- Cumming School of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, AB T2N4N1, Canada.
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6
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Intracellular Transport and Cytotoxicity of the Protein Toxin Ricin. Toxins (Basel) 2019; 11:toxins11060350. [PMID: 31216687 PMCID: PMC6628406 DOI: 10.3390/toxins11060350] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/13/2019] [Accepted: 06/14/2019] [Indexed: 12/17/2022] Open
Abstract
Ricin can be isolated from the seeds of the castor bean plant (Ricinus communis). It belongs to the ribosome-inactivating protein (RIP) family of toxins classified as a bio-threat agent due to its high toxicity, stability and availability. Ricin is a typical A-B toxin consisting of a single enzymatic A subunit (RTA) and a binding B subunit (RTB) joined by a single disulfide bond. RTA possesses an RNA N-glycosidase activity; it cleaves ribosomal RNA leading to the inhibition of protein synthesis. However, the mechanism of ricin-mediated cell death is quite complex, as a growing number of studies demonstrate that the inhibition of protein synthesis is not always correlated with long term ricin toxicity. To exert its cytotoxic effect, ricin A-chain has to be transported to the cytosol of the host cell. This translocation is preceded by endocytic uptake of the toxin and retrograde traffic through the trans-Golgi network (TGN) and the endoplasmic reticulum (ER). In this article, we describe intracellular trafficking of ricin with particular emphasis on host cell factors that facilitate this transport and contribute to ricin cytotoxicity in mammalian and yeast cells. The current understanding of the mechanisms of ricin-mediated cell death is discussed as well. We also comment on recent reports presenting medical applications for ricin and progress associated with the development of vaccines against this toxin.
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Challenges and Advances in SLE Autoantibody Detection and Interpretation. CURRENT TREATMENT OPTIONS IN RHEUMATOLOGY 2019. [DOI: 10.1007/s40674-019-00122-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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How Ricin Damages the Ribosome. Toxins (Basel) 2019; 11:toxins11050241. [PMID: 31035546 PMCID: PMC6562825 DOI: 10.3390/toxins11050241] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/17/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022] Open
Abstract
Ricin belongs to the group of ribosome-inactivating proteins (RIPs), i.e., toxins that have evolved to provide particular species with an advantage over other competitors in nature. Ricin possesses RNA N-glycosidase activity enabling the toxin to eliminate a single adenine base from the sarcin-ricin RNA loop (SRL), which is a highly conserved structure present on the large ribosomal subunit in all species from the three domains of life. The SRL belongs to the GTPase associated center (GAC), i.e., a ribosomal element involved in conferring unidirectional trajectory for the translational apparatus at the expense of GTP hydrolysis by translational GTPases (trGTPases). The SRL represents a critical element in the GAC, being the main triggering factor of GTP hydrolysis by trGTPases. Enzymatic removal of a single adenine base at the tip of SRL by ricin blocks GTP hydrolysis and, at the same time, impedes functioning of the translational machinery. Here, we discuss the consequences of SRL depurination by ricin for ribosomal performance, with emphasis on the mechanistic model overview of the SRL modus operandi.
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Human ribosomal P1-P2 heterodimer represents an optimal docking site for ricin A chain with a prominent role for P1 C-terminus. Sci Rep 2017; 7:5608. [PMID: 28717148 PMCID: PMC5514047 DOI: 10.1038/s41598-017-05675-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 06/15/2017] [Indexed: 12/26/2022] Open
Abstract
The eukaryotic P-stalk contains two P1-P2 protein dimers with a conserved C- terminal domain (CTD) critical for the interaction with external factors. To understand the role of the individual CTD of human P1/P2 proteins, we examined the interaction of reconstituted human P-protein complexes and C-terminally truncated forms with ricin A chain (RTA), which binds to the stalk to depurinate the sarcin/ricin loop (SRL). The interaction between P-protein complexes and RTA was examined by surface plasmon resonance, isothermal titration calorimetry, microscale thermophoresis and bio-layer interferometry. The P1-P2 heterodimer missing a CTD on P2 was able to bind RTA. In contrast, the P1-P2 heterodimer missing the CTD of P1 protein displayed almost no binding toward RTA. Very low interaction was detected between RTA and the non-truncated P2-P2 homodimer, suggesting that the structural architecture of the P1-P2 heterodimer is critical for binding RTA. The reconstituted pentameric human stalk complex had higher affinity for RTA than the P1-P2 dimer. Deletion of P1 CTD, but not P2 CTD reduced the affinity of the pentamer for RTA. These results highlight the importance of the heterodimeric organization of P1-P2 in the human stalk pentamer and functional non-equivalence of the individual P-protein CTDs in the interaction with RTA.
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Basu D, Tumer NE. Do the A subunits contribute to the differences in the toxicity of Shiga toxin 1 and Shiga toxin 2? Toxins (Basel) 2015; 7:1467-85. [PMID: 25938272 PMCID: PMC4448158 DOI: 10.3390/toxins7051467] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/23/2015] [Accepted: 04/27/2015] [Indexed: 12/25/2022] Open
Abstract
Shiga toxin producing Escherichia coli O157:H7 (STEC) is one of the leading causes of food-poisoning around the world. Some STEC strains produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2) or variants of either toxin, which are critical for the development of hemorrhagic colitis (HC) or hemolytic uremic syndrome (HUS). Currently, there are no therapeutic treatments for HC or HUS. E. coli O157:H7 strains carrying Stx2 are more virulent and are more frequently associated with HUS, which is the most common cause of renal failure in children in the US. The basis for the increased potency of Stx2 is not fully understood. Shiga toxins belong to the AB5 family of protein toxins with an A subunit, which depurinates a universally conserved adenine residue in the α-sarcin/ricin loop (SRL) of the 28S rRNA and five copies of the B subunit responsible for binding to cellular receptors. Recent studies showed differences in the structure, receptor binding, dependence on ribosomal proteins and pathogenicity of Stx1 and Stx2 and supported a role for the B subunit in differential toxicity. However, the current data do not rule out a potential role for the A1 subunits in the differential toxicity of Stx1 and Stx2. This review highlights the recent progress in understanding the differences in the A1 subunits of Stx1 and Stx2 and their role in defining toxicity.
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Affiliation(s)
- Debaleena Basu
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
| | - Nilgun E Tumer
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA.
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11
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Wawiórka L, Krokowski D, Gordiyenko Y, Krowarsch D, Robinson CV, Adam I, Grankowski N, Tchórzewski M. In vivo formation of Plasmodium falciparum ribosomal stalk - a unique mode of assembly without stable heterodimeric intermediates. Biochim Biophys Acta Gen Subj 2014; 1850:150-8. [PMID: 25450178 DOI: 10.1016/j.bbagen.2014.10.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 09/19/2014] [Accepted: 10/15/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND The ribosomal stalk composed of P-proteins constitutes a structure on the large ribosomal particle responsible for recruitment of translation factors and stimulation of factor-dependent GTP hydrolysis during translation. The main components of the stalk are P-proteins, which form a pentamer. Despite the conserved basic function of the stalk, the P-proteins do not form a uniform entity, displaying heterogeneity in the primary structure across the eukaryotic lineage. The P-proteins from protozoan parasites are among the most evolutionarily divergent stalk proteins. METHODS We have assembled P-stalk complex of Plasmodium falciparum in vivo in bacterial system using tricistronic expression cassette and provided its characteristics by biochemical and biophysical methods. RESULTS All three individual P-proteins, namely uL10/P0, P1 and P2, are indispensable for acquisition of a stable structure of the P stalk complex and the pentameric uL10/P0-(P1-P2)₂form represents the most favorable architecture for parasite P-proteins. CONCLUSION The formation of P. falciparum P-stalk is driven by trilateral interaction between individual elements which represents unique mode of assembling, without stable P1-P2 heterodimeric intermediate. GENERAL SIGNIFICANCE On the basis of our mass-spectrometry analysis supported by the bacterial two-hybrid assay and biophysical analyses, a unique pathway of the parasite stalk assembling has been proposed. We suggest that the absence of P1/P2 heterodimer, and the formation of a stable pentamer in the presence of all three proteins, indicate a one-step formation to be the main pathway for the vital ribosomal stalk assembly, whereas the P2 homo-oligomer may represent an off-pathway product with physiologically important nonribosomal role.
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Affiliation(s)
- Leszek Wawiórka
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Dawid Krokowski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Yuliya Gordiyenko
- Department of Chemistry, University of Oxford, South Parks Rd, Oxford OX1 3QZ, UK
| | - Daniel Krowarsch
- Department of Protein Biotechnology, Faculty of Biotechnology, University of Wroclaw, Tamka 2, 50-137 Wroclaw, Poland
| | - Carol V Robinson
- Department of Chemistry, University of Oxford, South Parks Rd, Oxford OX1 3QZ, UK
| | - Ishag Adam
- Department of Obstetrics & Gynecology, Faculty of Medicine, AlKaser Street, University of Khartoum, Khartoum, Sudan
| | - Nikodem Grankowski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Marek Tchórzewski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
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Lee KM, Yusa K, Chu LO, Yu CWH, Oono M, Miyoshi T, Ito K, Shaw PC, Wong KB, Uchiumi T. Solution structure of human P1•P2 heterodimer provides insights into the role of eukaryotic stalk in recruiting the ribosome-inactivating protein trichosanthin to the ribosome. Nucleic Acids Res 2013; 41:8776-87. [PMID: 23892290 PMCID: PMC3794596 DOI: 10.1093/nar/gkt636] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lateral ribosomal stalk is responsible for binding and recruiting translation factors during protein synthesis. The eukaryotic stalk consists of one P0 protein with two copies of P1•P2 heterodimers to form a P0(P1•P2)2 pentameric P-complex. Here, we have solved the structure of full-length P1•P2 by nuclear magnetic resonance spectroscopy. P1 and P2 dimerize via their helical N-terminal domains, whereas the C-terminal tails of P1•P2 are unstructured and can extend up to ∼125 Å away from the dimerization domains. 15N relaxation study reveals that the C-terminal tails are flexible, having a much faster internal mobility than the N-terminal domains. Replacement of prokaryotic L10(L7/L12)4/L11 by eukaryotic P0(P1•P2)2/eL12 rendered Escherichia coli ribosome, which is insensitive to trichosanthin (TCS), susceptible to depurination by TCS and the C-terminal tail was found to be responsible for this depurination. Truncation and insertion studies showed that depurination of hybrid ribosome is dependent on the length of the proline-alanine rich hinge region within the C-terminal tail. All together, we propose a model that recruitment of TCS to the sarcin-ricin loop required the flexible C-terminal tail, and the proline-alanine rich hinge region lengthens this C-terminal tail, allowing the tail to sweep around the ribosome to recruit TCS.
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Affiliation(s)
- Ka-Ming Lee
- School of Life Sciences, Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, Hong Kong, China and Department of Biology, Faculty of Science, Niigata University, Ikarashi 2-8050, Nishi-ku, Niigata 950-2181, Japan
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May KL, Yan Q, Tumer NE. Targeting ricin to the ribosome. Toxicon 2013; 69:143-51. [PMID: 23454625 DOI: 10.1016/j.toxicon.2013.02.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/01/2013] [Accepted: 02/06/2013] [Indexed: 12/15/2022]
Abstract
The plant toxin ricin is highly toxic for mammalian cells and is of concern for bioterrorism. Ricin belongs to a family of functionally related toxins, collectively referred to as ribosome inactivating proteins (RIPs), which disable ribosomes and halt protein synthesis. Currently there are no specific antidotes against ricin or related RIPs. The catalytic subunit of ricin is an N-glycosidase that depurinates a universally conserved adenine residue within the sarcin/ricin loop (SRL) of the 28S rRNA. This depurination activity inhibits translation and its biochemistry has been intensively studied. Yet, recent developments paint a more complex picture of toxicity, with ribosomal proteins and cellular signaling pathways contributing to the potency of ricin. In particular, several studies have now established the importance of the ribosomal stalk structure in facilitating the depurination activity and ribosome specificity of ricin and other RIPs. This review highlights recent developments defining toxin-ribosome interactions and examines the significance of these interactions for toxicity and therapeutic intervention.
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Affiliation(s)
- Kerrie L May
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901-8520, USA
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Baba K, Tumuraya K, Tanaka I, Yao M, Uchiumi T. Molecular dissection of the silkworm ribosomal stalk complex: the role of multiple copies of the stalk proteins. Nucleic Acids Res 2013; 41:3635-43. [PMID: 23376928 PMCID: PMC3616719 DOI: 10.1093/nar/gkt044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In animal ribosomes, two stalk proteins P1 and P2 form a heterodimer, and the two dimers, with the anchor protein P0, constitute a pentameric complex crucial for recruitment of translational GTPase factors to the ribosome. To investigate the functional contribution of each copy of the stalk proteins, we constructed P0 mutants, in which one of the two C-terminal helices, namely helix I (N-terminal side) or helix II (C-terminal side) were unable to bind the P1–P2 dimer. We also constructed ‘one-C-terminal domain (CTD) stalk dimers’, P1–P2ΔC and P1ΔC–P2, composed of intact P1/P2 monomer and a CTD-truncated partner. Through combinations of P0 and P1–P2 variants, various complexes were reconstituted and their function tested in eEF-2-dependent GTPase and eEF-1α/eEF-2-dependent polyphenylalanine synthesis assays in vitro. Double/single-CTD dimers bound to helix I showed higher activity than that bound to helix II. Despite low polypeptide synthetic activity by a single one-CTD dimer, its binding to both helices considerably increased activity, suggesting that two stalk dimers cooperate, particularly in polypeptide synthesis. This promotion of activity by two stalk dimers was lost upon mutation of the conserved YPT sequence connecting the two helices of P0, suggesting a role for this sequence in cooperativity of two stalk dimers.
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Affiliation(s)
- Kentaro Baba
- Department of Biology, Faculty of Science, Niigata University, Nishi-ku, Ikarashi-2, Niigata 950-2181, Japan
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May KL, Li XP, Martínez-Azorín F, Ballesta JPG, Grela P, Tchórzewski M, Tumer NE. The P1/P2 proteins of the human ribosomal stalk are required for ribosome binding and depurination by ricin in human cells. FEBS J 2012; 279:3925-36. [PMID: 22909382 DOI: 10.1111/j.1742-4658.2012.08752.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2012] [Revised: 08/14/2012] [Accepted: 08/16/2012] [Indexed: 01/30/2023]
Abstract
Ricin A-chain (RTA) depurinates the sarcin-ricin loop of 28S ribosomal RNA and inhibits protein synthesis in mammalian cells. In yeast, the ribosomal stalk facilitates the interaction of RTA with the ribosome and subsequent depurination. Despite homology between the stalk structures from yeast and humans, there are notable differences. The human ribosomal stalk contains two identical heterodimers of P1 and P2 bound to P0, whereas the yeast stalk consists of two different heterodimers, P1α-P2β and P2α-P1β, bound to P0. RTA exhibits higher activity towards mammalian ribosomes than towards ribosomes from other organisms, suggesting that the mode of interaction with ribosomes may vary. Here, we examined whether the human ribosomal stalk proteins facilitate the interaction of RTA with human ribosomes and subsequent depurination of the sarcin-ricin loop. Using small interfering RNA-mediated knockdown of P1/P2 expression in human cells, we demonstrated that the depurination activity of RTA is lower when P1 and P2 levels are reduced. Biacore analysis showed that ribosomes from P1/P2-depleted cells have a reduced ability to bind RTA, which correlates with reduced depurination activity both in vitro and inside cells. RTA interacts directly with recombinant human P1-P2 dimer, further demonstrating the importance of human P1 and P2 in enabling RTA to bind and depurinate human ribosomes.
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Affiliation(s)
- Kerrie L May
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901, USA
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Solution structure of the natively assembled yeast ribosomal stalk determined by small-angle X-ray scattering. Biochem J 2012; 444:205-9. [DOI: 10.1042/bj20120115] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ribosomal stalk of the 60S subunit has been shown to play a crucial role in all steps of protein synthesis, but its structure and exact molecular function remain an unanswered question. In the present study, we show the low-resolution models of the solution structure of the yeast ribosomal stalk, composed of five proteins, P0–(P1–P2)2. The model of the pentameric stalk complex determined by small-angle X-ray scattering reveals an elongated shape with a maximum length of 13 nm. The model displays three distinct lobes, which may correspond to the individual P1–P2 heterodimers anchored to the C-terminal domain of the P0 protein.
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NMR insights into folding and self-association of Plasmodium falciparum P2. PLoS One 2012; 7:e36279. [PMID: 22567147 PMCID: PMC3342256 DOI: 10.1371/journal.pone.0036279] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 04/04/2012] [Indexed: 11/19/2022] Open
Abstract
The eukaryotic 60S-ribosomal stalk is composed of acidic ribosomal proteins (P1 and P2) and neutral protein P0, which are thought to be associated as a pentameric structure, [2P1, 2P2, P0]. Plasmodium falciparum P2 (PfP2) appears to play additional non-ribosomal functions associated with its tendency for homo-oligomerization. Recombinant bacterially expressed PfP2 protein also undergoes self-association, as shown by SDS-PAGE analysis and light scattering studies. Secondary structure prediction algorithms predict the native PfP2 protein to be largely helical and this is corroborated by circular dichroism investigation. The 1H-15N HSQC spectrum of native P2 showed only 43 cross peaks compared to the expected 138. The observed peaks were found to belong to the C-terminal region, suggesting that this segment is flexible and solvent exposed. In 9 M urea denaturing conditions the chain exhibited mostly non-native β structural propensity. 15N Relaxation data for the denatured state indicated substantial variation in ms-µs time scale motion along the chain. Average area buried upon folding (AABUF) calculations on the monomer enabled identification of hydrophobic patches along the sequence. Interestingly, the segments of slower motion in the denatured state coincided with these hydrophobic patches, suggesting that in the denatured state the monomeric chain undergoes transient hydrophobic collapse. The implications of these results for the folding mechanism and self-association of PfP2 are discussed.
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Lee KM, Yu CWH, Chiu TYH, Sze KH, Shaw PC, Wong KB. Solution structure of the dimerization domain of the eukaryotic stalk P1/P2 complex reveals the structural organization of eukaryotic stalk complex. Nucleic Acids Res 2011; 40:3172-82. [PMID: 22135285 PMCID: PMC3326305 DOI: 10.1093/nar/gkr1143] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The lateral ribosomal stalk is responsible for the kingdom-specific binding of translation factors and activation of GTP hydrolysis during protein synthesis. The eukaryotic stalk is composed of three acidic ribosomal proteins P0, P1 and P2. P0 binds two copies of P1/P2 hetero-dimers to form a pentameric P-complex. The structure of the eukaryotic stalk is currently not known. To provide a better understanding on the structural organization of eukaryotic stalk, we have determined the solution structure of the N-terminal dimerization domain (NTD) of P1/P2 hetero-dimer. Helix-1, -2 and -4 from each of the NTD-P1 and NTD-P2 form the dimeric interface that buries 2200 A2 of solvent accessible surface area. In contrast to the symmetric P2 homo-dimer, P1/P2 hetero-dimer is asymmetric. Three conserved hydrophobic residues on the surface of NTD-P1 are replaced by charged residues in NTD-P2. Moreover, NTD-P1 has an extra turn in helix-1, which forms extensive intermolecular interactions with helix-1 and -4 of NTD-P2. Truncation of this extra turn of P1 abolished the formation of P1/P2 hetero-dimer. Systematic truncation studies suggest that P0 contains two spine-helices that each binds one copy of P1/P2 hetero-dimer. Modeling studies suggest that a large hydrophobic cavity, which can accommodate the loop between the spine-helices of P0, can be found on NTD-P1 but not on NTD-P2 when the helix-4 adopts an ‘open’ conformation. Based on the asymmetric properties of NTD-P1/NTD-P2, a structural model of the eukaryotic P-complex with P2/P1:P1/P2 topology is proposed.
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Affiliation(s)
- Ka-Ming Lee
- School of Life Sciences, Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Hong Kong, China
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Li XP, Grela P, Krokowski D, Tchórzewski M, Tumer NE. Pentameric organization of the ribosomal stalk accelerates recruitment of ricin a chain to the ribosome for depurination. J Biol Chem 2010; 285:41463-71. [PMID: 20974854 DOI: 10.1074/jbc.m110.171793] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Ribosome inactivating proteins (RIPs) depurinate a universally conserved adenine in the α-sarcin/ricin loop (SRL) and inhibit protein synthesis at the translation elongation step. We previously showed that ribosomal stalk is required for depurination of the SRL by ricin toxin A chain (RTA). The interaction between RTA and ribosomes was characterized by a two-step binding model, where the stalk structure could be considered as an important interacting element. Here, using purified yeast ribosomal stalk complexes assembled in vivo, we show a direct interaction between RTA and the isolated stalk complex. Detailed kinetic analysis of these interactions in real time using surface plasmon resonance (SPR) indicated that there is only one type of interaction between RTA and the ribosomal stalk, which represents one of the two binding steps of the interaction with ribosomes. Interactions of RTA with the isolated stalk were relatively insensitive to salt, indicating that nonelectrostatic interactions were dominant. We compared the interaction of RTA with the full pentameric stalk complex containing two pairs of P1/P2 proteins with its interaction with the trimeric stalk complexes containing only one pair of P1/P2 and found that the rate of association of RTA with the pentamer was higher than with either trimer. These results demonstrate that the stalk is the main landing platform for RTA on the ribosome and that pentameric organization of the stalk accelerates recruitment of RTA to the ribosome for depurination. Our results suggest that multiple copies of the stalk proteins might also increase the scavenging ability of the ribosome for the translational GTPases.
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Affiliation(s)
- Xiao-Ping Li
- Department of Plant Biology and Pathology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey 08901-8520, USA
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Lee KM, Yu CWH, Chan DSB, Chiu TYH, Zhu G, Sze KH, Shaw PC, Wong KB. Solution structure of the dimerization domain of ribosomal protein P2 provides insights for the structural organization of eukaryotic stalk. Nucleic Acids Res 2010; 38:5206-16. [PMID: 20385603 PMCID: PMC2926600 DOI: 10.1093/nar/gkq231] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The lateral stalk of ribosome is responsible for kingdom-specific binding of translation factors and activation of GTP hydrolysis that drives protein synthesis. In eukaryotes, the stalk is composed of acidic ribosomal proteins P0, P1 and P2 that constitute a pentameric P-complex in 1: 2: 2 ratio. We have determined the solution structure of the N-terminal dimerization domain of human P2 (NTD-P2), which provides insights into the structural organization of the eukaryotic stalk. Our structure revealed that eukaryotic stalk protein P2 forms a symmetric homodimer in solution, and is structurally distinct from the bacterial counterpart L12 homodimer. The two subunits of NTD-P2 form extensive hydrophobic interactions in the dimeric interface that buries 2400 Å2 of solvent accessible surface area. We have showed that P1 can dissociate P2 homodimer spontaneously to form a more stable P1/P2 1 : 1 heterodimer. By homology modelling, we identified three exposed polar residues on helix-3 of P2 are substituted by conserved hydrophobic residues in P1. Confirmed by mutagenesis, we showed that these residues on helix-3 of P1 are not involved in the dimerization of P1/P2, but instead play a vital role in anchoring P1/P2 heterodimer to P0. Based on our results, models of the eukaryotic stalk complex were proposed.
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Affiliation(s)
- Ka-Ming Lee
- Department of Biochemistry, Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Hong Kong, China
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Francisco-Velilla R, Remacha M. In vivo formation of a stable pentameric (P2alpha/P1beta)-P0-(P1alpha/P2beta) ribosomal stalk complex in Saccharomyces cerevisiae. Yeast 2010; 27:693-704. [PMID: 20225338 DOI: 10.1002/yea.1765] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Heterodimers of acidic proteins P1alpha/P2beta and P1beta/P2alpha bind to P0 and are fundamental for the assembly of the ribosomal stalk. However, different inconsistencies are found in the literature regarding additional P protein heterodimer formations and their individual interactions with P0. Using the two-hybrid approach, we have found results that help to clarify these interactions. Thus, we have found that neither P1 nor P2 directly interact with P0 unless the endogenous heterodimer partner is being expressed in the cell. In addition, a P2-free amino end is a requisite in these heterodimers for binding to P0. With regard to the two-hybrid interactions between P1 and P2, the known canonical P1alpha-P2beta and P1beta-P2alpha interactions do not depend on either a free amino end or the presence of endogenous P0, P1 or P2 proteins. Furthermore, the non-canonical P1beta-P2beta pair also behaves similarly, although this interaction is weaker. Interestingly, P1alpha-P2alpha, P1alpha-P1beta and P2alpha-P2beta two-hybrid interactions were also detected, although in these cases the endogenous P proteins were involved. Thus, these positive interactions are the consequence of the interaction between two canonical heterodimers. As the ribosome anchorage protein P0 is also necessary, the results suggest that, in vivo, all five P proteins form a complex, independent of the ribosome, containing the two canonical heterodimers and P0. This complex has been isolated in cells expressing a P0 protein unable to bind to the ribosome.
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Grela P, Krokowski D, Gordiyenko Y, Krowarsch D, Robinson CV, Otlewski J, Grankowski N, Tchórzewski M. Biophysical Properties of the Eukaryotic Ribosomal Stalk. Biochemistry 2010; 49:924-33. [DOI: 10.1021/bi901811s] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Przemysław Grela
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Dawid Krokowski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Yuliya Gordiyenko
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB21EW, United Kingdom
| | - Daniel Krowarsch
- Laboratory of Protein Engineering, University of Wroclaw, Tamka 2, 50-137 Wroclaw, Poland
| | - Carol V. Robinson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB21EW, United Kingdom
| | - Jacek Otlewski
- Laboratory of Protein Engineering, University of Wroclaw, Tamka 2, 50-137 Wroclaw, Poland
| | - Nikodem Grankowski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
| | - Marek Tchórzewski
- Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland
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Kolaiti RM, Lucas JM, Kouyanou-Koutsoukou S. Molecular cloning of the ribosomal P-proteins MgP1, MgP2, MgP0, and superoxide dismutase (SOD) in the mussel Mytilus galloprovincialis and analysis of MgP0 at stress conditions. Gene 2009; 430:77-85. [DOI: 10.1016/j.gene.2008.10.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 10/27/2008] [Accepted: 10/28/2008] [Indexed: 10/21/2022]
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Abstract
The 'stalk' is a large ribosomal subunit domain that regulates translation. In the present study the role of the ribosomal stalk P proteins in modulating ribosomal activity has been investigated in human cells using RNA interference. A strong down-regulation of P2 mRNA and a drastic decrease in P2 protein in a stable human cell line was achieved using a doxycycline-inducible system. Interestingly, the amount of P1 protein was similarly decreased in these cells, in contrast with the expression of P1 mRNA. The loss of P1/P2 proteins produced a decrease in the growth rate of these cells, as well as an altered polysome pattern with reduced translation efficiency, but without affecting the free 40 S/60 S subunit ratio. A decrease in the ribosomal-subunit joining capacity was also observed. These data indicate that P1/P2 proteins modulate cytoplasmic translation by influencing the interaction between subunits, thereby regulating the rate of cell proliferation.
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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]
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