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Roesmann F, Sertznig H, Klaassen K, Wilhelm A, Heininger D, Heß S, Elsner C, Marschalek R, Santiago ML, Esser S, Sutter K, Dittmer U, Widera M. The interferon-regulated host factor hnRNPA0 modulates HIV-1 production by interference with LTR activity, mRNA trafficking, and programmed ribosomal frameshifting. J Virol 2024; 98:e0053424. [PMID: 38899932 PMCID: PMC11265465 DOI: 10.1128/jvi.00534-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
The interplay between host factors and viral components impacts viral replication efficiency profoundly. Members of the cellular heterogeneous nuclear ribonucleoprotein family (hnRNPs) have been extensively studied as HIV-1 host dependency factors, but whether they play a role in innate immunity is currently unknown. This study aimed to identify hnRNPA0 as a type I interferon (IFN)-repressed host factor in HIV-1-infected cells. Knockdown of hnRNPA0, a situation that mirrors conditions under IFN stimulation, increased LTR activity, export of unspliced HIV-1 mRNA, viral particle production, and thus, increased infectivity. Conversely, hnRNPA0 overexpression primarily reduced plasmid-driven and integrated HIV-1 long terminal repeat (LTR) activity, significantly decreasing total viral mRNA and protein levels. In addition, high levels of hnRNPA0 significantly reduced the HIV-1 programmed ribosomal frameshifting efficiency, resulting in a shift in the HIV-1 p55/p15 ratio. The HIV-1 alternative splice site usage remained largely unaffected by altered hnRNPA0 levels suggesting that the synergistic inhibition of the LTR activity and viral mRNA transcription, as well as impaired ribosomal frameshifting efficiency, are critical factors for efficient HIV-1 replication regulated by hnRNPA0. The pleiotropic dose-dependent effects under high or low hnRNPA0 levels were further confirmed in HIV-1-infected Jurkat cells. Finally, our study revealed that hnRNPA0 levels in PBMCs were lower in therapy-naive HIV-1-infected individuals compared to healthy controls. Our findings highlight a significant role for hnRNPA0 in HIV-1 replication and suggest that its IFN-I-regulated expression levels are critical for viral fitness allowing replication in an antiviral environment.IMPORTANCERNA-binding proteins, in particular, heterogeneous nuclear ribonucleoproteins (hnRNPs), have been extensively studied. Some act as host dependency factors for HIV-1 since they are involved in multiple cellular gene expression processes. Our study revealed hnRNPA0 as an IFN-regulated host factor, that is differently expressed after IFN-I treatment in HIV-1 target cells and lower expressed in therapy-naïve HIV-1-infected individuals. Our findings demonstrate the significant pleiotropic role of hnRNPA0 in viral replication: In high concentrations, hnRNPA0 limits viral replication by negatively regulating Tat-LTR transcription, retaining unspliced mRNA in the nucleus, and significantly impairing programmed ribosomal frameshifting. Low hnRNPA0 levels as observed in IFN-treated THP-1 cells, particularly facilitate HIV LTR activity and unspliced mRNA export, suggesting a role in innate immunity in favor of HIV replication. Understanding the mode of action between hnRNPA0 and HIV-1 gene expression might help to identify novel therapeutically strategies against HIV-1 and other viruses.
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Affiliation(s)
- Fabian Roesmann
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Helene Sertznig
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Katleen Klaassen
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Alexander Wilhelm
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Delia Heininger
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Stefanie Heß
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
| | - Carina Elsner
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Rolf Marschalek
- Institute of Pharmaceutical Biology, Goethe-University, Frankfurt am Main, Hessen, Germany
| | - Mario L. Santiago
- Department of Medicine, University of Colorado Denver, Aurora, Colorado, USA
| | - Stefan Esser
- Institute for the Research on HIV and AIDS-associated Diseases University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Department of Dermatology, HPSTD Outpatient Clinic, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Kathrin Sutter
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Institute for the Research on HIV and AIDS-associated Diseases University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Ulf Dittmer
- Institute for Virology, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- Institute for the Research on HIV and AIDS-associated Diseases University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Marek Widera
- Goethe University Frankfurt, University Hospital, Institute for Medical Virology, Frankfurt, Germany
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2
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Bermejo GA, Tjandra N, Clore GM, Schwieters CD. Xplor-NIH: Better parameters and protocols for NMR protein structure determination. Protein Sci 2024; 33:e4922. [PMID: 38501482 PMCID: PMC10962493 DOI: 10.1002/pro.4922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 03/20/2024]
Abstract
The present work describes an update to the protein covalent geometry and atomic radii parameters in the Xplor-NIH biomolecular structure determination package. In combination with an improved treatment of selected non-bonded interactions between atoms three bonds apart, such as those involving methyl hydrogens, and a previously developed term that affects the system's gyration volume, the new parameters are tested using structure calculations on 30 proteins with restraints derived from nuclear magnetic resonance data. Using modern structure validation criteria, including several formally adopted by the Protein Data Bank, and a clear measure of structural accuracy, the results show superior performance relative to previous Xplor-NIH implementations. Additionally, the Xplor-NIH structures compare favorably against originally determined NMR models.
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Affiliation(s)
- Guillermo A. Bermejo
- Laboratory of Chemical PhysicsNational Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaMarylandUSA
| | - Nico Tjandra
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of HealthBethesdaMarylandUSA
| | - G. Marius Clore
- Laboratory of Chemical PhysicsNational Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaMarylandUSA
| | - Charles D. Schwieters
- Laboratory of Chemical PhysicsNational Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of HealthBethesdaMarylandUSA
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3
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Sharma T, Kundu N, Kaur S, Shankaraswamy J, Saxena S. Why to target G-quadruplexes using peptides: Next-generation G4-interacting ligands. J Pept Sci 2023; 29:e3491. [PMID: 37009771 DOI: 10.1002/psc.3491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 04/04/2023]
Abstract
Guanine-rich oligonucleotides existing in both DNA and RNA are able to fold into four-stranded DNA secondary structures via Hoogsteen type hydrogen-bonding, where four guanines self-assemble into a square planar arrangement, which, when stacked upon each other, results in the formation of higher-order structures called G-quadruplexes. Their distribution is not random; they are more frequently present at telomeres, proto-oncogenic promoters, introns, 5'- and 3'-untranslated regions, stem cell markers, ribosome binding sites and so forth and are associated with various biological functions, all of which play a pivotal role in various incurable diseases like cancer and cellular ageing. Several studies have suggested that G-quadruplexes could not regulate biological processes by themselves; instead, various proteins take part in this regulation and can be important therapeutic targets. There are certain limitations in using whole G4-protein for therapeutics purpose because of its high manufacturing cost, laborious structure prediction, dynamic nature, unavailability for oral administration due to its degradation in the gut and inefficient penetration to reach the target site because of the large size. Hence, biologically active peptides can be the potential candidates for therapeutic intervention instead of the whole G4-protein complex. In this review, we aimed to clarify the biological roles of G4s, how we can identify them throughout the genome via bioinformatics, the proteins interacting with G4s and how G4-interacting peptide molecules may be the potential next-generation ligands for targeting the G4 motifs located in biologically important regions.
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Affiliation(s)
- Taniya Sharma
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Nikita Kundu
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Sarvpreet Kaur
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
| | - Jadala Shankaraswamy
- Department of Fruit Science, College of Horticulture, Mojerla, Sri Konda Laxman Telangana State Horticultural University, Budwel, Telangana, India
| | - Sarika Saxena
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Noida, India
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4
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Malaney P, Benitez O, Zhang X, Post SM. Assessing the role of intrinsic disorder in RNA-binding protein function: hnRNP K as a case study. Methods 2022; 208:59-65. [DOI: 10.1016/j.ymeth.2022.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/20/2022] [Accepted: 10/26/2022] [Indexed: 11/09/2022] Open
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5
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The Role of RNA-Binding Proteins in Hematological Malignancies. Int J Mol Sci 2022; 23:ijms23179552. [PMID: 36076951 PMCID: PMC9455611 DOI: 10.3390/ijms23179552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/18/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022] Open
Abstract
Hematological malignancies comprise a plethora of different neoplasms, such as leukemia, lymphoma, and myeloma, plus a myriad of dysplasia, such as myelodysplastic syndromes or anemias. Despite all the advances in patient care and the development of new therapies, some of these malignancies remain incurable, mainly due to resistance and refractoriness to treatment. Therefore, there is an unmet clinical need to identify new biomarkers and potential therapeutic targets that play a role in treatment resistance and contribute to the poor outcomes of these tumors. RNA-binding proteins (RBPs) are a diverse class of proteins that interact with transcripts and noncoding RNAs and are involved in every step of the post-transcriptional processing of transcripts. Dysregulation of RBPs has been associated with the development of hematological malignancies, making them potential valuable biomarkers and potential therapeutic targets. Although a number of dysregulated RBPs have been identified in hematological malignancies, there is a critical need to understand the biology underlying their contribution to pathology, such as the spatiotemporal context and molecular mechanisms involved. In this review, we emphasize the importance of deciphering the regulatory mechanisms of RBPs to pinpoint novel therapeutic targets that could drive or contribute to hematological malignancy biology.
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6
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D'Souza MH, Mrozowich T, Badmalia MD, Geeraert M, Frederickson A, Henrickson A, Demeler B, Wolfinger MT, Patel TR. Biophysical characterisation of human LincRNA-p21 sense and antisense Alu inverted repeats. Nucleic Acids Res 2022; 50:5881-5898. [PMID: 35639511 PMCID: PMC9177966 DOI: 10.1093/nar/gkac414] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 04/26/2022] [Accepted: 05/09/2022] [Indexed: 12/05/2022] Open
Abstract
Human Long Intergenic Noncoding RNA-p21 (LincRNA-p21) is a regulatory noncoding RNA that plays an important role in promoting apoptosis. LincRNA-p21 is also critical in down-regulating many p53 target genes through its interaction with a p53 repressive complex. The interaction between LincRNA-p21 and the repressive complex is likely dependent on the RNA tertiary structure. Previous studies have determined the two-dimensional secondary structures of the sense and antisense human LincRNA-p21 AluSx1 IRs using SHAPE. However, there were no insights into its three-dimensional structure. Therefore, we in vitro transcribed the sense and antisense regions of LincRNA-p21 AluSx1 Inverted Repeats (IRs) and performed analytical ultracentrifugation, size exclusion chromatography, light scattering, and small angle X-ray scattering (SAXS) studies. Based on these studies, we determined low-resolution, three-dimensional structures of sense and antisense LincRNA-p21. By adapting previously known two-dimensional information, we calculated their sense and antisense high-resolution models and determined that they agree with the low-resolution structures determined using SAXS. Thus, our integrated approach provides insights into the structure of LincRNA-p21 Alu IRs. Our study also offers a viable pipeline for combining the secondary structure information with biophysical and computational studies to obtain high-resolution atomistic models for long noncoding RNAs.
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Affiliation(s)
- Michael H D'Souza
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Tyler Mrozowich
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Maulik D Badmalia
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Mitchell Geeraert
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Angela Frederickson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Amy Henrickson
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Borries Demeler
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada.,Department of Chemistry and Biochemistry, University of Montana, Missoula, MT 59812, USA.,NorthWest Biophysics Consortium, University of Lethbridge, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Michael T Wolfinger
- Bioinformatics and Computational Biology, Faculty of Computer Science, Währingerstrasse 29, 1090 Vienna, Austria.,Department of Theoretical Chemistry, University of Vienna, Währingerstrasse 17, 1090 Vienna, Austria
| | - Trushar R Patel
- Department of Chemistry and Biochemistry, Alberta RNA Research and Training Institute, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada.,Department of Microbiology, Immunology and Infectious Disease, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada.,Li Ka Shing Institute of Virology and Discovery Lab, University of Alberta, Edmonton, AB T6G 2E1, Canada
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7
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Low YH, Asi Y, Foti SC, Lashley T. Heterogeneous Nuclear Ribonucleoproteins: Implications in Neurological Diseases. Mol Neurobiol 2020; 58:631-646. [PMID: 33000450 PMCID: PMC7843550 DOI: 10.1007/s12035-020-02137-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/17/2020] [Indexed: 12/13/2022]
Abstract
Heterogenous nuclear ribonucleoproteins (hnRNPs) are a complex and functionally diverse family of RNA binding proteins with multifarious roles. They are involved, directly or indirectly, in alternative splicing, transcriptional and translational regulation, stress granule formation, cell cycle regulation, and axonal transport. It is unsurprising, given their heavy involvement in maintaining functional integrity of the cell, that their dysfunction has neurological implications. However, compared to their more established roles in cancer, the evidence of hnRNP implication in neurological diseases is still in its infancy. This review aims to consolidate the evidences for hnRNP involvement in neurological diseases, with a focus on spinal muscular atrophy (SMA), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), multiple sclerosis (MS), congenital myasthenic syndrome (CMS), and fragile X-associated tremor/ataxia syndrome (FXTAS). Understanding more about hnRNP involvement in neurological diseases can further elucidate the pathomechanisms involved in these diseases and perhaps guide future therapeutic advances.
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Affiliation(s)
- Yi-Hua Low
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,Duke-NUS Medical School, Singapore, Singapore
| | - Yasmine Asi
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Sandrine C Foti
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - Tammaryn Lashley
- The Queen Square Brain Bank for Neurological Disorders, Department of Clinical and Movement Disorders, UCL Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK. .,Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, University College London, London, UK.
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8
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Abstract
Mammalian genomes are extensively transcribed, which produces a large number of both coding and non-coding transcripts. Various RNAs are physically associated with chromatin, through being either retained in cis at their site of transcription or recruited in trans to other genomic regions. Driven by recent technological innovations for detecting chromatin-associated RNAs, diverse roles are being revealed for these RNAs and associated RNA-binding proteins (RBPs) in gene regulation and genome function. Such functions include locus-specific roles in gene activation and silencing, as well as emerging roles in higher-order genome organization, such as involvement in long-range enhancer-promoter interactions, transcription hubs, heterochromatin, nuclear bodies and phase transitions.
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Affiliation(s)
- Xiao Li
- Department of Cellular and Molecular Medicine and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Xiang-Dong Fu
- Department of Cellular and Molecular Medicine and Institute for Genomic Medicine, University of California, San Diego, La Jolla, CA, USA.
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9
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Castagnoli L, Mandaliti W, Nepravishta R, Valentini E, Mattioni A, Procopio R, Iannuccelli M, Polo S, Paci M, Cesareni G, Santonico E. Selectivity of the CUBAN domain in the recognition of ubiquitin and NEDD8. FEBS J 2019; 286:653-677. [PMID: 30659753 DOI: 10.1111/febs.14752] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/25/2018] [Accepted: 12/28/2018] [Indexed: 12/27/2022]
Abstract
Among the members of the ubiquitin-like (Ubl) protein family, neural precursor cell expressed developmentally down-regulated protein 8 (NEDD8) is the closest in sequence to ubiquitin (57% identity). The two modification mechanisms and their functions, however, are highly distinct and the two Ubls are not interchangeable. A complex network of interactions between modifying enzymes and adaptors, most of which are specific while others are promiscuous, ensures selectivity. Many domains that bind the ubiquitin hydrophobic patch also bind NEDD8 while no domain that specifically binds NEDD8 has yet been described. Here, we report an unbiased selection of domains that bind ubiquitin and/or NEDD8 and we characterize their specificity/promiscuity. Many ubiquitin-binding domains bind ubiquitin preferentially and, to a lesser extent, NEDD8. In a few cases, the affinity of these domains for NEDD8 can be increased by substituting the alanine at position 72 with arginine, as in ubiquitin. We have also identified a unique domain, mapping to the carboxyl end of the protein KHNYN, which has a stark preference for NEDD8. Given its ability to bind neddylated cullins, we have named this domain CUBAN (Cullin-Binding domain Associating with NEDD8). We present here the solution structure of the CUBAN domain both in the isolated form and in complex with NEDD8. The results contribute to the understanding of the discrimination mechanism between ubiquitin and the Ubl. They also provide new insights on the biological role of a ill-defined protein, whose function is hitherto only predicted.
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Affiliation(s)
| | - Walter Mandaliti
- Department of Chemical Sciences and Technologies, Tor Vergata University, Rome, Italy
| | - Ridvan Nepravishta
- Department of Chemical Sciences and Technologies, Tor Vergata University, Rome, Italy.,School of Pharmacy East Anglia, University of Norwich, UK
| | | | - Anna Mattioni
- Department of Biology, Tor Vergata University, Rome, Italy
| | - Radha Procopio
- Department of Biology, Tor Vergata University, Rome, Italy.,Institute of Molecular Bioimaging and Physiology, CNR, Catanzaro, Italy
| | | | - Simona Polo
- IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy.,DIPO, Dipartimento di Oncologia ed Emato-oncologia, University of Milan, Italy
| | - Maurizio Paci
- Department of Chemical Sciences and Technologies, Tor Vergata University, Rome, Italy
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10
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Ostareck DH, Ostareck-Lederer A. RNA-Binding Proteins in the Control of LPS-Induced Macrophage Response. Front Genet 2019; 10:31. [PMID: 30778370 PMCID: PMC6369361 DOI: 10.3389/fgene.2019.00031] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 01/17/2019] [Indexed: 12/18/2022] Open
Abstract
Innate immune response is triggered by pathogen components, like lipopolysaccharides (LPS) of gram-negative bacteria. LPS initiates Toll-like receptor 4 (TLR4) signaling, which involves mitogen activated protein kinases (MAPK) and nuclear factor kappa B (NFκB) in different pathway branches and ultimately induces inflammatory cytokine and chemokine expression, macrophage migration and phagocytosis. Timely gene transcription and post-transcriptional control of gene expression confer the adequate synthesis of signaling molecules. As trans-acting factors RNA binding proteins (RBPs) contribute significantly to the surveillance of gene expression. RBPs are involved in the regulation of mRNA processing, localization, stability and translation. Thereby they enable rapid cellular responses to inflammatory mediators and facilitate a coordinated systemic immune response. Specific RBP binding to conserved sequence motifs in their target mRNAs is mediated by RNA binding domains, like Zink-finger domains, RNA recognition motifs (RRM), and hnRNP K homology domains (KH), often arranged in modular arrays. In this review, we focus on RBPs Tristetraprolin (TTP), human antigen R (HUR), T-cell intracellular antigen 1 related protein (TIAR), and heterogeneous ribonuclear protein K (hnRNP K) in LPS induced macrophages as primary responding immune cells. We discuss recent experiments employing RNA immunoprecipitation and microarray analysis (RIP-Chip) and newly developed individual-nucleotide resolution crosslinking and immunoprecipitation (iCLIP), photoactivatable ribonucleoside-enhanced crosslinking (PAR-iCLIP) and RNA sequencing techniques (RNA-Seq). The global mRNA interaction profile analysis of TTP, HUR, TIAR, and hnRNP K exhibited valuable information about the post-transcriptional control of inflammation related gene expression with a broad impact on intracellular signaling and temporal cytokine expression.
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Affiliation(s)
- Dirk H Ostareck
- Department of Intensive Care Medicine, University Hospital RWTH Aachen, Aachen, Germany
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Sutherland C, Cui Y, Mao H, Hurley LH. A Mechanosensor Mechanism Controls the G-Quadruplex/i-Motif Molecular Switch in the MYC Promoter NHE III1. J Am Chem Soc 2016; 138:14138-14151. [DOI: 10.1021/jacs.6b09196] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Caleb Sutherland
- University of Arizona Cancer Center, 1515 North Campbell Avenue, Tucson, Arizona 85724, United States
| | - Yunxi Cui
- Department
of Chemistry and Biochemistry and School of Biomedical Sciences, Kent State University, Kent, Ohio 44242, United States
| | - Hanbin Mao
- Department
of Chemistry and Biochemistry and School of Biomedical Sciences, Kent State University, Kent, Ohio 44242, United States
| | - Laurence H. Hurley
- University of Arizona Cancer Center, 1515 North Campbell Avenue, Tucson, Arizona 85724, United States
- University of Arizona, College of Pharmacy, 1703 East Mabel Street, Tucson, Arizona 85721, United States
- BIO5 Institute, 1657 East
Helen Street, Tucson, Arizona 85721, United States
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Suk FM, Lin SY, Lin RJ, Hsine YH, Liao YJ, Fang SU, Liang YC. Bortezomib inhibits Burkitt's lymphoma cell proliferation by downregulating sumoylated hnRNP K and c-Myc expression. Oncotarget 2016; 6:25988-6001. [PMID: 26317903 PMCID: PMC4694880 DOI: 10.18632/oncotarget.4620] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 07/06/2015] [Indexed: 11/26/2022] Open
Abstract
Bortezomib (Velcal) was the first proteasome inhibitor to be approved by the US Food and Drug Administration to treat patients with relapsed/refractory multiple myelomas. Previous studies have demonstrated that bortezomib inhibits tumor cell proliferation and induces apoptosis by blocking the nuclear factor (NF)-κB pathway. However, the exact mechanism by which bortezomib induces cancer cell apoptosis is still not well understood. In this study, we found that bortezomib significantly inhibited cell proliferation in both human Burkitt's lymphoma CA46 and Daudi cells. Through proteomic analysis, we found that bortezomib treatment changed the expression of various proteins in distinct functional categories including unfolding protein response (UPS), RNA processing, protein targeting and biosynthesis, apoptosis, and signal transduction. Among the proteins with altered expression, hnRNP K, hnRNP H, Hsp90α, Grp78, and Hsp7C were common to both Daudi and CA46 cells. Interestingly, bortezomib treatment downregulated the expression of high-molecular-weight (HMw) hnRNP K and c-Myc but upregulated the expression of low-molecular-weight (LMw) hnRNP K. Moreover, cell proliferation was significantly correlated with high expression of HMw hnRNP K and c-Myc. HMw and LMw hnRNP K were identified as sumoylated and desumoylated hnRNP K, respectively. Using transient transfection, we found that sumoylated hnRNP K increased c-Myc expression at the translational level and contributed to cell proliferation, and that Lys422 of hnRNP K is the candidate sumoylated residue. Our results suggest that besides inhibiting the ubiquitin-proteasome pathway, bortezomib may inhibit cell proliferation by downregulating sumoylated hnRNP K and c-Myc expression in Burkitt's lymphoma cells.
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Affiliation(s)
- Fat-Moon Suk
- Division of Gastroenterology, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.,Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Shyr-Yi Lin
- Department of Primary Care Medicine, Taipei Medical University Hospital, Taipei, Taiwan.,Department of General Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Ren-Jye Lin
- Department of Primary Care Medicine, Taipei Medical University Hospital, Taipei, Taiwan.,Department of General Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yung-Hsin Hsine
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yen-Ju Liao
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Sheng-Uei Fang
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Division of Gastroenterology and Hepatology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Yu-Chih Liang
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.,Traditional Herbal Medicine Research Center, Taipei Medical University Hospital, Taipei, Taiwan
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13
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Cytoplasmic Accumulation of Heterogeneous Nuclear Ribonucleoprotein K Strongly Promotes Tumor Invasion in Renal Cell Carcinoma Cells. PLoS One 2015; 10:e0145769. [PMID: 26713736 PMCID: PMC4699215 DOI: 10.1371/journal.pone.0145769] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 12/08/2015] [Indexed: 11/29/2022] Open
Abstract
Heterogeneous nuclear ribonucleoprotein (hnRNP) K is a part of the ribonucleoprotein complex which regulates diverse biological events. While overexpression of hnRNP K has been shown to be related to tumorigenesis in several cancers, both the expression patterns and biological mechanisms of hnRNP K in renal cell carcinoma (RCC) cells remain unclear. In this study, we showed that hnRNP K protein was strongly expressed in selected RCC cell lines (ACHN, A498, Caki-1, 786–0), and knock-down of hnRNP K expression by siRNA induced cell growth inhibition and apoptosis. Based on immunohistochemical (IHC) analysis of hnRNP K expression in human clear cell RCC specimens, we demonstrated that there was a significant positive correlation between hnRNP K staining score and tumor aggressiveness (e.g., Fuhrman grade, metastasis). Particularly, the rate of cytoplasmic localization of hnRNP K in primary RCC with distant metastasis was significantly higher than that in RCC without metastasis. Additionally, our results indicated that the cytoplasmic distribution of hnRNP K induced by TGF-β stimulus mainly contributed to TGF-β-triggered tumor cell invasion in RCC cells. Dominant cytoplasmic expression of ectopic hnRNP K markedly suppressed the inhibition of invasion by knock-down of endogenous hnRNP K. The expression level of matrix metalloproteinase protein-2 was decreased by endogenous hnRNP K knock-down, and restored by ectopic hnRNP K. Therefore, hnRNP K may be a key molecule involved in cell motility in RCC cells, and molecular mechanism associated with the subcellular localization of hnRNP K may be a novel target in the treatment of metastatic RCC.
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14
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Newman R, McHugh J, Turner M. RNA binding proteins as regulators of immune cell biology. Clin Exp Immunol 2015. [PMID: 26201441 DOI: 10.1111/cei.12684] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sequence-specific RNA binding proteins (RBP) are important regulators of the immune response. RBP modulate gene expression by regulating splicing, polyadenylation, localization, translation and decay of target mRNAs. Increasing evidence suggests that RBP play critical roles in the development, activation and function of lymphocyte populations in the immune system. This review will discuss the post-transcriptional regulation of gene expression by RBP during lymphocyte development, with particular focus on the Tristetraprolin family of RBP.
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Affiliation(s)
- R Newman
- Babraham Institute, Cambridge, UK
| | - J McHugh
- Babraham Institute, Cambridge, UK
| | - M Turner
- Babraham Institute, Cambridge, UK
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15
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Tian Y, Schwieters CD, Opella SJ, Marassi FM. A practical implicit solvent potential for NMR structure calculation. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 243:54-64. [PMID: 24747742 PMCID: PMC4037354 DOI: 10.1016/j.jmr.2014.03.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/18/2014] [Accepted: 03/20/2014] [Indexed: 05/30/2023]
Abstract
The benefits of protein structure refinement in water are well documented. However, performing structure refinement with explicit atomic representation of the solvent molecules is computationally expensive and impractical for NMR-restrained structure calculations that start from completely extended polypeptide templates. Here we describe a new implicit solvation potential, EEFx (Effective Energy Function for XPLOR-NIH), for NMR-restrained structure calculations of proteins in XPLOR-NIH. The key components of EEFx are an energy term for solvation energy that works together with other nonbonded energy functions, and a dedicated force field for conformational and nonbonded protein interaction parameters. The initial results obtained with EEFx show that significant improvements in structural quality can be obtained. EEFx is computationally efficient and can be used both to fold and refine structures. Overall, EEFx improves the quality of protein conformation and nonbonded atomic interactions. Moreover, such benefits are accompanied by enhanced structural precision and enhanced structural accuracy, reflected in improved agreement with the cross-validated dipolar coupling data. Finally, implementation of EEFx calculations is straightforward and computationally efficient. Overall, EEFx provides a useful method for the practical calculation of experimental protein structures in a physically realistic environment.
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Affiliation(s)
- Ye Tian
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA; Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0307, USA
| | - Charles D Schwieters
- Division of Computational Bioscience, Building 12A, Center for Information Technology, National Institutes of Health, Bethesda, MD 20892-5624, USA
| | - Stanley J Opella
- Department of Chemistry and Biochemistry, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0307, USA
| | - Francesca M Marassi
- Sanford-Burnham Medical Research Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
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16
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Bazak R, Ressl J, Raha S, Doty C, Liu W, Wanzer B, Salam SA, Elwany S, Paunesku T, Woloschak GE. Cytotoxicity and DNA cleavage with core-shell nanocomposites functionalized by a KH domain DNA binding peptide. NANOSCALE 2013; 5:11394-11399. [PMID: 23824281 PMCID: PMC3825787 DOI: 10.1039/c3nr02203j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A nanoconjugate was composed of metal oxide nanoparticles decorated with peptides and fluorescent dye and tested for DNA cleavage following UV light activation. The peptide design was based on a DNA binding domain, the so called KH domain of the hnRNPK protein. This "KH peptide" enabled cellular uptake of nanoconjugates and their entry into cell nuclei. The control nanoconjugate carried no peptide; it consisted only of the metal oxide nanoparticle prepared as Fe3O4@TiO2 nanocomposite and the fluorescent dye alizarin red S. These components of either construct are responsible for nanoconjugate activation by UV light and the resultant production of reactive oxygen species (ROS). Production of ROS at different subcellular locations causes damage to different components of cells: only nanoconjugates inside cell nuclei can be expected to cause DNA cleavage. Degradation of cellular DNA with KH peptide decorated nanoconjugates exceeded the DNA damage obtained from control, no-peptide nanoconjugate counterparts. Moreover, caspase activation and cell death were more extensive in the same cells.
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Affiliation(s)
- Remon Bazak
- Department of Otorhinolaryngology and Head & Neck Surgery, University of Alexandria Medical School, Azarita medical campus, Champlollion Street, Khartoum Square, Alexandria, Egypt. Tel: 01003810548
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - Jan Ressl
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - Sumita Raha
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - Caroline Doty
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - William Liu
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - Beau Wanzer
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - Seddik Abdel Salam
- Department of Otorhinolaryngology and Head & Neck Surgery, University of Alexandria Medical School, Azarita medical campus, Champlollion Street, Khartoum Square, Alexandria, Egypt. Tel: 01003810548
| | - Samy Elwany
- Department of Otorhinolaryngology and Head & Neck Surgery, University of Alexandria Medical School, Azarita medical campus, Champlollion Street, Khartoum Square, Alexandria, Egypt. Tel: 01003810548
| | - Tatjana Paunesku
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
| | - Gayle E Woloschak
- Departments of Radiation Oncology and Radiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611 USA. Fax: 312-577-0751; Tel: 312-503-4322
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17
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Menon V, Vallat BK, Dybas JM, Fiser A. Modeling proteins using a super-secondary structure library and NMR chemical shift information. Structure 2013; 21:891-9. [PMID: 23685209 DOI: 10.1016/j.str.2013.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 04/02/2013] [Accepted: 04/13/2013] [Indexed: 11/29/2022]
Abstract
A remaining challenge in protein modeling is to predict structures for sequences with no sequence similarity to any experimentally solved structure. Based on earlier observations, the library of protein backbone supersecondary structure motifs (Smotifs) saturated about a decade ago. Therefore, it should be possible to build any structure from a combination of existing Smotifs with the help of limited experimental data that are sufficient to relate the backbone conformations of Smotifs between target proteins and known structures. Here, we present a hybrid modeling algorithm that relies on an exhaustive Smotif library and on nuclear magnetic resonance chemical shift patterns without any input of primary sequence information. In a test of 102 proteins, the algorithm delivered 90 homology-model-quality models, among them 24 high-quality ones, and a topologically correct solution for almost all cases. The current approach opens a venue to address the modeling of larger protein structures for which chemical shifts are available.
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Affiliation(s)
- Vilas Menon
- Department of Systems and Computational Biology, Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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18
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Bermejo GA, Clore GM, Schwieters CD. Smooth statistical torsion angle potential derived from a large conformational database via adaptive kernel density estimation improves the quality of NMR protein structures. Protein Sci 2012; 21:1824-36. [PMID: 23011872 DOI: 10.1002/pro.2163] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/14/2012] [Accepted: 09/17/2012] [Indexed: 11/09/2022]
Abstract
Statistical potentials that embody torsion angle probability densities in databases of high-quality X-ray protein structures supplement the incomplete structural information of experimental nuclear magnetic resonance (NMR) datasets. By biasing the conformational search during the course of structure calculation toward highly populated regions in the database, the resulting protein structures display better validation criteria and accuracy. Here, a new statistical torsion angle potential is developed using adaptive kernel density estimation to extract probability densities from a large database of more than 10⁶ quality-filtered amino acid residues. Incorporated into the Xplor-NIH software package, the new implementation clearly outperforms an older potential, widely used in NMR structure elucidation, in that it exhibits simultaneously smoother and sharper energy surfaces, and results in protein structures with improved conformation, nonbonded atomic interactions, and accuracy.
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Affiliation(s)
- Guillermo A Bermejo
- Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892-5624, USA
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19
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Haglund E, Danielsson J, Kadhirvel S, Lindberg MO, Logan DT, Oliveberg M. Trimming down a protein structure to its bare foldons: spatial organization of the cooperative unit. J Biol Chem 2011; 287:2731-8. [PMID: 22117065 DOI: 10.1074/jbc.m111.312447] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Folding of the ribosomal protein S6 is a malleable process controlled by two competing, and partly overlapping, folding nuclei. Together, these nuclei extend over most of the S6 structure, except the edge strand β2, which is consistently missing in the folding transition states; despite being part of the S6 four-stranded sheet, β2 seems not to be part of the cooperative unit of the protein. The question is then whether β2 can be removed from the S6 structure without compromising folding cooperativity or native state integrity. To investigate this, we constructed a truncated variant of S6 lacking β2, reducing the size of the protein from 96 to 76 residues (S6(Δβ2)). The new S6 variant expresses well in Escherichia coli and has a well dispersed heteronuclear single quantum correlation spectrum and a perfectly wild-type-like crystal structure, but with a smaller three-stranded β-sheet. Moreover, S6(Δβ2) displays an archetypical v-shaped chevron plot with decreased slope of the unfolding limb, as expected from a protein with maintained folding cooperativity and reduced size. The results support the notion that foldons, as defined by the structural distribution of the folding nuclei, represent a property-based level of hierarchy in the build-up of larger protein structures and suggest that the role of β2 in S6 is mainly in intermolecular binding, consistent with the position of this strand in the ribosomal assembly.
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Affiliation(s)
- Ellinor Haglund
- Department of Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, S-106 91 Stockholm, Sweden
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20
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Xue B, Oldfield CJ, Van YY, Dunker AK, Uversky VN. Protein intrinsic disorder and induced pluripotent stem cells. MOLECULAR BIOSYSTEMS 2011; 8:134-50. [PMID: 21761058 DOI: 10.1039/c1mb05163f] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Induced pluripotent stem (iPS) cells can be obtained from terminally differentiated somatic cells by overexpression of defined sets of reprogramming transcription factors. These protein sets have been called the Yamanaka factors, namely Sox2, Oct3/4 (Pou5f1), Klf4, and c-Myc, and the Thomson factors, namely Sox2, Oct3, Lin28, and Nanog. Other sets of proteins, while not essential for the formation of iPS cells, are important for improving the efficiency of the induction and still other sets of proteins are important as markers for embryonic stem cells. Structural information about most of these important proteins is very sparse. Our bioinformatics analysis herein reveals that these reprogramming factors and most of the efficiency-improving and embryonic stem cell markers are highly enriched in intrinsic disorder. As is typical for transcription factors, these proteins are modular. Specific sites for interaction with other proteins and DNA are dispersed in the long regions of intrinsic disorder. These highly dynamic interaction sites are evidently responsible for the delicate interplay among various molecules. The bioinformatics analysis given herein should facilitate the investigation of the roles and organization of these modular interaction sites, thereby helping to shed further light on the pathways that underlie the mechanism(s) by which terminally differentiated cells are converted to iPS cells.
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Affiliation(s)
- Bin Xue
- Department of Molecular Medicine, College of Medicine, University of South Florida, Tampa, Florida 33612, USA.
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21
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Wang Y, Fang H, Cao Y, Liu LS, Jiang M. Jintang Black Goat (Capra hircas) hnRNP K: Molecular Cloning, Sequence Analysis and Expression Detection. JOURNAL OF APPLIED ANIMAL RESEARCH 2010. [DOI: 10.1080/09712119.2010.10539503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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22
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Costa-Junior HM, Garavello NM, Duarte ML, Berti DA, Glaser T, de Andrade A, Labate CA, Ferreira ATDS, Perales JEA, Xavier-Neto J, Krieger JE, Schechtman D. Phosphoproteomics profiling suggests a role for nuclear βΙPKC in transcription processes of undifferentiated murine embryonic stem cells. J Proteome Res 2010; 9:6191-206. [PMID: 20936827 DOI: 10.1021/pr100355k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Protein kinase C (PKC) plays a key role in embryonic stem cell (ESC) proliferation, self-renewal, and differentiation. However, the function of specific PKC isoenzymes have yet to be determined. Of the PKCs expressed in undifferentiated ESCs, βIPKC was the only isoenzyme abundantly expressed in the nuclei. To investigate the role of βΙPKC in these cells, we employed a phosphoproteomics strategy and used two classical (cPKC) peptide modulators and one βIPKC-specific inhibitor peptide. We identified 13 nuclear proteins that are direct or indirect βΙPKC substrates in undifferentiated ESCs. These proteins are known to be involved in regulating transcription, splicing, and chromatin remodeling during proliferation and differentiation. Inhibiting βΙPKC had no effect on DNA synthesis in undifferentiated ESCs. However, upon differentiation, many cells seized to express βΙPKC and βΙPKC was frequently found in the cytoplasm. Taken together, our results suggest that βIPKC takes part in the processes that maintain ESCs in their undifferentiated state.
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23
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Wen F, Shen A, Shanas R, Bhattacharyya A, Lian F, Hostetter G, Shi J. Higher expression of the heterogeneous nuclear ribonucleoprotein k in melanoma. Ann Surg Oncol 2010; 17:2619-27. [PMID: 20499280 DOI: 10.1245/s10434-010-1121-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Indexed: 01/22/2023]
Abstract
BACKGROUND The heterogeneous nuclear ribonucleoprotein (hnRNP) K is an essential RNA and DNA binding protein involved in gene expression and signal transduction. The role of hnRNP K in cancer is relatively understudied. However, several cellular functions strongly indicate that hnRNP K is involved in tumorigenesis. Oncogenes c-Src, c-myc, and eIF4E are regulated by hnRNP K. We have shown an increased cytoplasmic hnRNP K in pancreatic cancer. In the present study, we investigated the altered expression of hnRNP K protein and its correlation with p-ERK in melanoma using human melanoma cell lines and tissue microarray. MATERIALS AND METHODS The protein levels of hnRNP K and p-ERK in 8 human melanoma cell lines and a melanoma progression tissue microarray containing 80 melanoma, 23 dysplastic nevi, and 14 benign nevi specimens were analyzed using Western blot and immunohistochemistry analysis. hnRNP K was knocked down by siRNA, and its effect on melanoma cells was assessed. RESULTS We showed a higher hnRNP K protein level in both melanoma cell lines and melanoma tissue specimens, which correlated with a higher c-myc expression. An increase in the cytoplasmic hnRNP K and eIF4E protein levels in melanoma cells is also seen. p-ERK level was also higher in dysplastic nevi and melanoma tissues, but did not correlate with hnRNP K protein level. We then demonstrated that knocking down of hnRNP K by siRNA inhibited melanoma cell growth and colony formation, as well as c-myc expression. CONCLUSIONS hnRNP K expression correlated with melanoma and may play a role in melanoma tumorigenesis.
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Affiliation(s)
- Fushi Wen
- Department of Surgery, Arizona Cancer Center, University of Arizona, Tucson, AZ, USA
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24
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Zhou R, Shanas R, Nelson MA, Bhattacharyya A, Shi J. Increased expression of the heterogeneous nuclear ribonucleoprotein K in pancreatic cancer and its association with the mutant p53. Int J Cancer 2010; 126:395-404. [PMID: 19609950 DOI: 10.1002/ijc.24744] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The heterogeneous nuclear ribonucleoprotein (hnRNP) K is an essential RNA and DNA binding protein involved in gene expression and signal transduction including DNA transcription, RNA splicing, RNA stability and translation. The role of hnRNP K in cancer is relatively understudied. However, several cellular functions strongly indicate that hnRNP K is involved in tumorigenesis. In this study, we investigated the altered protein expression and the subcellular distribution of the hnRNP K protein using tissue microarrays in pancreatic cancer. We showed an increased cytoplasmic hnRNP K in pancreatic cancer. This increase in hnRNP K protein occurs at the posttranscriptional level. We postulate that the cytoplasmic accumulation of hnRNP K will lead to silenced mRNA translation of tumor suppressor genes and thus contributes to pancreatic cancer development. We also demonstrated that knocking down of hnRNP K expression by siRNA inhibited pancreatic cancer cell growth and colony formation. hnRNP K was identified as a member of the p53/HDM2 pathway. Whether hnRNP K interacts with the mutant p53 is not known. Using two different pancreatic cancer cell lines, we can demonstrate that hnRNP K interacts with the mutant p53. The subcellular distribution and function of the mutant p53 and the interaction of hnRNP K/mutant p53 were affected by the Ras/MEK/ERK pathway, growth factors and the specific p53 mutations in pancreatic cancer cells. Since Kras is activated and p53 is mutated in most pancreatic cancers, these data unveiled an important new signaling pathway that linked by hnRNP K and mutant p53 in pancreatic cancer tumorigenesis.
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Affiliation(s)
- Renyuan Zhou
- Department of Urology, Fifth People's Hospital of Shanghai, P.R. China
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25
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Evaluation of liposome populations using a sucrose density gradient centrifugation approach coupled to a continuous flow system. Anal Chim Acta 2009; 645:79-85. [DOI: 10.1016/j.aca.2009.04.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 04/22/2009] [Accepted: 04/29/2009] [Indexed: 11/17/2022]
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26
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Du Z, Fenn S, Tjhen R, James TL. Structure of a construct of a human poly(C)-binding protein containing the first and second KH domains reveals insights into its regulatory mechanisms. J Biol Chem 2008; 283:28757-66. [PMID: 18701464 PMCID: PMC2568903 DOI: 10.1074/jbc.m803046200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 08/01/2008] [Indexed: 11/06/2022] Open
Abstract
Poly(C)-binding proteins (PCBPs) are important regulatory proteins that contain three KH (hnRNP K homology) domains. Binding poly(C) D/RNA sequences via KH domains is essential for multiple PCBP functions. To reveal the basis for PCBP-D/RNA interactions and function, we determined the structure of a construct containing the first two domains (KH1-KH2) of human PCBP2 by NMR. KH1 and KH2 form an intramolecular pseudodimer. The large hydrophobic dimerization surface of each KH domain is on the side opposite the D/RNA binding interface. Chemical shift mapping indicates both domains bind poly(C) DNA motifs without disrupting the KH1-KH2 interaction. Spectral comparison of KH1-KH2, KH3, and full-length PCBP2 constructs suggests that the KH1-KH2 pseudodimer forms, but KH3 does not interact with other parts of the protein. From NMR studies and modeling, we propose possible modes of cooperative binding tandem poly(C) motifs by the KH domains. D/RNA binding may induce pseudodimer dissociation or stabilize dissociated KH1 and KH2, making protein interaction surfaces available to PCBP-binding partners. This conformational change may represent a regulatory mechanism linking D/RNA binding to PCBP functions.
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Affiliation(s)
- Zhihua Du
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, USA
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27
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García-Mayoral MF, Hollingworth D, Masino L, Díaz-Moreno I, Kelly G, Gherzi R, Chou CF, Chen CY, Ramos A. The structure of the C-terminal KH domains of KSRP reveals a noncanonical motif important for mRNA degradation. Structure 2007; 15:485-98. [PMID: 17437720 DOI: 10.1016/j.str.2007.03.006] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2006] [Revised: 03/01/2007] [Accepted: 03/14/2007] [Indexed: 10/23/2022]
Abstract
The AU-rich element (ARE) RNA-binding protein KSRP (K-homology splicing regulator protein) contains four KH domains and promotes the degradation of specific mRNAs that encode proteins with functions in cellular proliferation and inflammatory response. The fourth KH domain (KH4) is essential for mRNA recognition and decay but requires the third KH domain (KH3) for its function. We show that KH3 and KH4 behave as independent binding modules and can interact with different regions of the AU-rich RNA targets of KSRP. This provides KSRP with the structural flexibility needed to recognize a set of different targets in the context of their 3'UTR structural settings. Surprisingly, we find that KH4 binds to its target AREs with lower affinity than KH3 and that KSRP's mRNA binding, and mRNA degradation activities are closely associated with a conserved structural element of KH4.
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28
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Fenn S, Du Z, Lee JK, Tjhen R, Stroud RM, James TL. Crystal structure of the third KH domain of human poly(C)-binding protein-2 in complex with a C-rich strand of human telomeric DNA at 1.6 A resolution. Nucleic Acids Res 2007; 35:2651-60. [PMID: 17426136 PMCID: PMC1885661 DOI: 10.1093/nar/gkm139] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
KH (hnRNP K homology) domains, consisting of ∼70 amino acid residues, are present in a variety of nucleic-acid-binding proteins. Among these are poly(C)-binding proteins (PCBPs), which are important regulators of mRNA stability and posttranscriptional regulation in general. All PCBPs contain three different KH domains and recognize poly(C)-sequences with high affinity and specificity. To reveal the molecular basis of poly(C)-sequence recognition, we have determined the crystal structure, at 1.6 Å resolution, of PCBP2 KH3 domain in complex with a 7-nt DNA sequence (5′-AACCCTA-3′) corresponding to one repeat of the C-rich strand of human telomeric DNA. The domain assumes a type-I KH fold in a βααββα configuration. The protein–DNA interface could be studied in unprecedented detail and is made up of a series of direct and water-mediated hydrogen bonds between the protein and the DNA, revealing an especially dense network involving several structural water molecules for the last 2 nt in the core recognition sequence. Unlike published KH domain structures, the protein crystallizes without protein–protein contacts, yielding new insights into the dimerization properties of different KH domains. A nucleotide platform, an interesting feature found in some RNA molecules, was identified, evidently for the first time in DNA.
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Affiliation(s)
- Sebastian Fenn
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2280, USA
| | - Zhihua Du
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2280, USA
| | - John K. Lee
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2280, USA
| | - Richard Tjhen
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2280, USA
| | - Robert M. Stroud
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2280, USA
| | - Thomas L. James
- Department of Pharmaceutical Chemistry and Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143-2280, USA
- *To whom correspondence should be addressed +1-415 476-1916+1-415-502-8298
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29
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Brykailo MA, Corbett AH, Fridovich-Keil JL. Functional overlap between conserved and diverged KH domains in Saccharomyces cerevisiae SCP160. Nucleic Acids Res 2007; 35:1108-18. [PMID: 17264125 PMCID: PMC1994781 DOI: 10.1093/nar/gkl1160] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 12/20/2006] [Accepted: 12/20/2006] [Indexed: 01/26/2023] Open
Abstract
The K homology (KH) domain is a remarkably versatile and highly conserved RNA-binding motif. Classical KH domains include a characteristic pattern of hydrophobic residues, a Gly-X-X-Gly (GXXG) segment, and a variable loop. KH domains typically occur in clusters, with some retaining their GXXG sequence (conserved), while others do not (diverged). As a first step towards addressing whether GXXG is essential for KH-domain function, we explored the roles of conserved and diverged KH domains in Scp160p, a multiple-KH-domain-containing protein in Saccharomyces cerevisiae. We specifically wanted to know (1) whether diverged KH domains were essential for Scp160p function, and (2) whether diverged KH domains could functionally replace conserved KH domains. To address these questions, we deleted and/or interchanged conserved and diverged KH domains of Scp160p and expressed the mutated alleles in yeast. Our results demonstrated that the answer to each question was yes. Both conserved and diverged KH domains are essential for Scp160p function, and diverged KH domains can function in place of conserved KH domains. These findings challenge the prevailing notions about the requisite features of a KH domain and raise the possibility that there may be more functional KH domains in the proteome than previously appreciated.
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Affiliation(s)
- Melissa A. Brykailo
- Graduate Program in Genetics and Molecular Biology, Emory University Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 and Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Anita H. Corbett
- Graduate Program in Genetics and Molecular Biology, Emory University Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 and Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Judith L. Fridovich-Keil
- Graduate Program in Genetics and Molecular Biology, Emory University Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322 and Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
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30
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Guzmán B, Cormand B, Ribasés M, González-Núñez D, Botey A, Poch E. Implication of chromosome 18 in hypertension by sibling pair and association analyses: putative involvement of the RKHD2 gene. Hypertension 2006; 48:883-91. [PMID: 17015768 DOI: 10.1161/01.hyp.0000244085.52918.a0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study aims to test the implication of regions on chromosomes 9, 17, and 18 in essential hypertension (EH) by combining sibling-pair linkage analysis and case-control association studies. The selection of these chromosomal regions is based on previous evidence of their implication in EH or in related phenotypes by comparative genomics in several rat models and from genome-wide linkage studies in humans. For the affected sibling-pair linkage analysis, 27 microsatellite markers were genotyped in 56 pedigrees from Spain with hypertensive sibling pairs. Linkage analysis showed significant excess allele sharing at the D18S474 marker on 18q21.1, as shown by maximum likelihood of allele sharing methods (logarithm of odds=3.24; P=0.00011) and nonparametric linkage calculations (nonparametric linkage=3.32; P=0.00044). On the contrary, no significant results with any of the markers analyzed on chromosomes 9 and 17 were obtained. We further focused on the Ring finger and KH domain containing 2 (RKHD2) gene located 6 Kb distal from D18S474 and performed a case-control association study based on linkage disequilibrium in 112 hypertensive patients and 156 control subjects. We selected 2 RKHD2-tagged single nucleotide polymorphisms, rs1941958 and rs1893379, covering, in terms of linkage disequilibrium, the entire gene, and observed a significant overrepresentation of the rs1941958G-rs1893379T RKHD2 haplotype in the group of hypertensive patients in comparison with controls (2P=0.0004; odds ratio: 2.32). We also detected epistatic effects between the 2 RKHD2 single nucleotide polymorphisms (2P=0.002; odds ratio: 2.48). Our data confirm the implication of chromosome 18 in EH and support a contribution of RKHD2 to the genetic susceptibility of this complex phenotype.
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Affiliation(s)
- Blanca Guzmán
- Servei de Nefrologia, Hospital Clínic, Universitat de Barcelona, Villarroel 170, 08036 Barcelona, Spain
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31
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Malik AK, Flock KE, Godavarthi CL, Loh HH, Ko JL. Molecular basis underlying the poly C binding protein 1 as a regulator of the proximal promoter of mouse mu-opioid receptor gene. Brain Res 2006; 1112:33-45. [PMID: 16904079 DOI: 10.1016/j.brainres.2006.07.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 06/07/2006] [Accepted: 07/05/2006] [Indexed: 11/19/2022]
Abstract
Previous studies showed poly C binding protein 1 (PCBP) participating in the mu-opioid receptor (MOR) gene regulation via binding to a single-stranded (ss) DNA element. In this report, we therefore investigate the molecular basis of PCBP regulating the MOR gene expression. Various truncated PCBPs, including one domain (KH1, KH2, variable or KH3), two- (K12, K2v or Kv3) or three-sequential domains (K12v or K2v3), were constructed. The MOR ssDNA binding abilities of these truncated PCBPs were examined using electrophoretic mobility shift assay (EMSA). KH1 domain possessed a strong MOR ssDNA binding activity. Variable domain displayed no binding, and KH2 or KH3 domain possessed a weak MOR ssDNA binding activity. Binding of two-domain PCBPs indicated an additive effect of two-domain combinations. Interestingly, K2v3, a three-domain PCBP, displayed as strong ssDNA binding as that of K12v, suggesting synergism of KH2, KH3 and variable domains for the binding activity. Functional analysis demonstrated one-domain PCBPs exhibiting no transactivation on the MOR proximal promoter. Two-domain PCBPs displayed approximately 20% activity, while three-domain PCBPs displayed 70%-85% of full-length PCBP activity. Taken together, these results suggested that no single domain possessed sufficient functional activity to serve as an independent transactivation domain, and the combination of three sequential domains was necessary for its optimal activity to activate the MOR proximal promoter. In summary, our data suggested that cooperativity of three sequential domains is essential for PCBP functioning as a MOR gene regulator. Various ways in which this cooperativity could occur are discussed.
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MESH Headings
- Animals
- Base Sequence
- Carrier Proteins/physiology
- Cell Line, Tumor
- DNA-Binding Proteins
- Electrophoretic Mobility Shift Assay/methods
- Gene Expression Regulation/physiology
- Methionine/metabolism
- Mice
- Neuroblastoma
- Phosphorus Isotopes/metabolism
- Promoter Regions, Genetic/physiology
- Protein Binding/drug effects
- Protein Binding/physiology
- Protein Structure, Tertiary/physiology
- RNA, Messenger/metabolism
- RNA-Binding Proteins
- Receptors, Opioid, mu/genetics
- Receptors, Opioid, mu/metabolism
- Regulatory Sequences, Nucleic Acid
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Transcription, Genetic
- Transfection/methods
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Affiliation(s)
- Adnan K Malik
- Department of Biology, Seton Hall University, 208 McNulty Hall, 400 South Orange Ave. South Orange, NJ 07079, USA
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32
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Messias AC, Harnisch C, Ostareck-Lederer A, Sattler M, Ostareck DH. The DICE-binding activity of KH domain 3 of hnRNP K is affected by c-Src-mediated tyrosine phosphorylation. J Mol Biol 2006; 361:470-81. [PMID: 16854432 DOI: 10.1016/j.jmb.2006.06.025] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 05/09/2006] [Accepted: 06/12/2006] [Indexed: 10/24/2022]
Abstract
hnRNP K and hnRNP E1/E2 are RNA-binding proteins comprised of three hnRNP K-homology (KH) domains. These proteins are involved in the translational control and stabilization of mRNAs in erythroid cells. hnRNP E1 and hnRNP K regulate the translation of reticulocyte 15-lipoxygenase (r15-LOX) mRNA. Both proteins bind specifically to the differentiation control element (DICE) in the 3' untranslated region (3'UTR) of the r15-LOX mRNA. It has been shown that hnRNP K is a substrate of the tyrosine kinase c-Src and that tyrosine phosphorylation by c-Src inhibits the binding of hnRNP K to the DICE. Here, we investigate which of the three KH domains of hnRNP E1 and hnRNP K mediate the DICE interaction. Using RNA-binding assays, we demonstrate DICE-binding of the KH domains 1 and 3 of hnRNP E1, and KH domain 3 of hnRNP K. Furthermore, with RNA-binding assays, NMR experiments and in vitro translation studies, we show that tyrosine 458 in KH domain 3 of hnRNP K is important for the DICE interaction and we provide evidence that it is a target of c-Src.
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Affiliation(s)
- Ana C Messias
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany
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33
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Harris D, Zhang Z, Chaubey B, Pandey VN. Identification of cellular factors associated with the 3'-nontranslated region of the hepatitis C virus genome. Mol Cell Proteomics 2006; 5:1006-18. [PMID: 16500930 DOI: 10.1074/mcp.m500429-mcp200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Chronic infection by hepatitis C virus (HCV) is the leading cause of severe hepatitis that often develops into liver cirrhosis and hepatocellular carcinoma. The molecular mechanisms underlying HCV replication and pathogenesis are poorly understood. Similarly, the role(s) of host factors in the replication of HCV remains largely undefined. Based on our knowledge of other RNA viruses, it is likely that a number of cellular factors may be involved in facilitating HCV replication. It has been demonstrated that elements within the 3'-nontranslated region (3'-NTR) of the (+) strand HCV genome are essential for initiation of (-) strand synthesis. The RNA signals within the highly conserved 3'-NTR may be the site for recruiting cellular factors that mediate virus replication/pathogenesis. However, the identities of putative cellular factors interacting with these RNA signals remain unknown. In this report, we demonstrate that an RNA affinity capture system developed in our laboratory used in conjunction with LC/MS/MS allowed us to positively identify more than 70 cellular proteins that interact with the 3'-NTR (+) of HCV. Binding of these cellular proteins was not competed out by a 10-fold excess of nonspecific competitor RNA. With few exceptions, all of the identified cellular proteins are RNA-binding proteins whose reported cellular functions provide unique insights into host cell-virus interactions and possible mechanisms influencing HCV replication and HCV-associated pathogenesis. Small interfering RNA-mediated silencing of selected 3'-NTR-binding proteins in an HCV replicon cell line reduced replicon RNA to undetectable levels, suggesting important roles for these cellular factors in HCV replication.
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Affiliation(s)
- Dylan Harris
- Department of Biochemistry and Molecular Biology and Centre for the Study of Emerging and Re-emerging Pathogens, University of Medicine and Dentistry of New Jersey--New Jersey Medical School, Newark, New Jersey 07103, USA
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34
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Mikula M, Karczmarski J, Dzwonek A, Rubel T, Hennig E, Dadlez M, Bujnicki JM, Bomsztyk K, Ostrowski J. Casein kinases phosphorylate multiple residues spanning the entire hnRNP K length. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2006; 1764:299-306. [PMID: 16448870 DOI: 10.1016/j.bbapap.2005.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Revised: 12/01/2005] [Accepted: 12/04/2005] [Indexed: 11/25/2022]
Abstract
Heterogeneous Nuclear Ribonucleoprotein K (hnRNP K) is an RNA/DNA-binding protein involved in many processes that regulate gene expression. K protein's pleiotropic action reflects the diversity of its molecular interactions. Many of these interactions have been shown to be regulated by phosphorylation. K protein contains more than seventy potential phosphorylation sites. We used an integrated approach of mass spectrometry and computer analysis to explore patterns of K protein phosphorylation. We found that in vitro a single kinase can phosphorylate K protein on multiple sites spanning the entire length of the protein, including residues contained within the RNA/DNA-binding domains. 2-D gel electrophoresis of K protein purified from cells identified 5-8 spots. Mass spectrometry of K protein isolated from proliferating cells and from cells under oxidative stress revealed the same pattern of phosphopeptides. The structural implications of phosphorylation are discussed.
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35
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Mertens HDT, Gooley PR. Validating the use of database potentials in protein structure determination by NMR. FEBS Lett 2005; 579:5542-8. [PMID: 16219311 DOI: 10.1016/j.febslet.2005.09.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 08/17/2005] [Accepted: 09/09/2005] [Indexed: 11/26/2022]
Abstract
The refinement of protein structures determined by nuclear magnetic resonance spectroscopy against database potentials of mean force allows for the exclusion of unfavourable conformations of the protein backbone during a structure calculation, resulting in protein structures with a marked improvement in Ramachandran statistics. In this communication, we use multiple sets of residual dipolar couplings as quality assessment criteria for several proteins and show that not only do the Ramachandran and structural quality statistics improve, but a significant improvement in the accuracy of structures is achieved upon refinement.
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Affiliation(s)
- Haydyn D T Mertens
- Department of Biochemistry and Molecular Biology, Bio21 Institute of Biotechnology and Molecular Science, University of Melbourne, Parkville, Vic., Australia
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36
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Backe PH, Messias AC, Ravelli RBG, Sattler M, Cusack S. X-Ray Crystallographic and NMR Studies of the Third KH Domain of hnRNP K in Complex with Single-Stranded Nucleic Acids. Structure 2005; 13:1055-67. [PMID: 16004877 DOI: 10.1016/j.str.2005.04.008] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
The heterogeneous nuclear ribonucleoprotein (hnRNP) K is implicated in multiple functions in the regulation of gene expression and acts as a hub at the intersection of signaling pathways and processes involving nucleic acids. Central to its function is its ability to bind both ssDNA and ssRNA via its KH (hnRNP K homology) domains. We determined crystal structures of hnRNP K KH3 domain complexed with 15-mer and 6-mer (CTC(4)) ssDNAs at 2.4 and 1.8 A resolution, respectively, and show that the KH3 domain binds specifically to both TCCC and CCCC sequences. In parallel, we used NMR to compare the binding affinity and mode of interaction of the KH3 domain with several ssRNA ligands and CTC(4) ssDNA. Based on a structure alignment of the KH3-CTC(4) complex with known structures of other KH domains in complex with ssRNA, we discuss recognition of tetranucleotide sequences by KH domains.
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Affiliation(s)
- Paul H Backe
- Grenoble Outstation, European Molecular Biology Laboratory, 6 rue Jules Horowitz, BP 181, F-38042 Grenoble Cedex 9, France
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37
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Sidiqi M, Wilce JA, Porter CJ, Barker A, Leedman PJ, Wilce MCJ. Formation of an alphaCP1-KH3 complex with UC-rich RNA. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:423-9. [PMID: 15756586 DOI: 10.1007/s00249-005-0467-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2004] [Revised: 01/14/2005] [Accepted: 01/28/2005] [Indexed: 11/29/2022]
Abstract
The alphaCP family of proteins [also known as poly(C)-binding or heterogeneous nuclear ribonucleoprotein E proteins] are involved in the regulation of messenger RNA (mRNA) stability and translational efficiency. They bind via their triple heterologous nuclear ribonucleoprotein K homology (KH) domain structures to C-rich mRNA, and are thought to interact with other mRNA-binding proteins as well as provide direct nuclease protection. In particular, alphaCP1 and alphaCP2 have been shown to bind to a specific region of androgen receptor (AR) mRNA, resulting in its increased stability. The roles of each of the KH motifs in the binding affinity and the specificity is not yet understood. We report the beginning of a systematic study of each of the alphaCP KH domains, with the cloning and expression of alphaCP1-KH2 and alphaCP1-KH3. We report the ability of alphaCP1-KH3, but not alphaCP1-KH2, to bind the target AR mRNA sequence using an RNA electrophoretic mobility gel shift assay. We also report the preparation of an alphaCP1-KH3/AR mRNA complex for structural studies. (1)H-(15)N heteronuclear single quantum correlation NMR spectra of (15)N-labelled alphaCP1-KH3 verified the integrity and good solution behaviour of the purified domain. The titration of the 11-nucleotide RNA target sequence from AR mRNA resulted in a rearrangement of the (1)H-(15)N correlations, demonstrating the complete binding of the protein to form a homogeneous protein/RNA complex suitable for future structural studies.
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Affiliation(s)
- M Sidiqi
- School of Biomedical and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
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38
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Paziewska A, Wyrwicz LS, Bujnicki JM, Bomsztyk K, Ostrowski J. Cooperative binding of the hnRNP K three KH domains to mRNA targets. FEBS Lett 2005; 577:134-40. [PMID: 15527774 DOI: 10.1016/j.febslet.2004.08.086] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2004] [Revised: 08/11/2004] [Accepted: 08/29/2004] [Indexed: 11/23/2022]
Abstract
The heterogeneous nuclear ribonucleoprotein (hnRNP) K homology (KH) domain is an evolutionarily conserved module that binds short ribonucleotide sequences. KH domains most often are present in multiple copies per protein. In vitro studies of hnRNP K and other KH domain bearing proteins have yielded conflicting results regarding the relative contribution of each KH domain to the binding of target RNAs. To assess this RNA-binding we used full-length hnRNP K, its fragments and the yeast ortholog as baits in the yeast three-hybrid system. The results demonstrate that in this heterologous in vivo system, the three KH domains bind RNA synergistically and that a single KH domain, in comparison, binds RNA weakly.
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Affiliation(s)
- Agnieszka Paziewska
- Department of Gastroenterology, Medical Center for Postgraduate Education, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
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Sidiqi M, Wilce JA, Vivian JP, Porter CJ, Barker A, Leedman PJ, Wilce MCJ. Structure and RNA binding of the third KH domain of poly(C)-binding protein 1. Nucleic Acids Res 2005; 33:1213-21. [PMID: 15731341 PMCID: PMC549569 DOI: 10.1093/nar/gki265] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Poly(C)-binding proteins (CPs) are important regulators of mRNA stability and translational regulation. They recognize C-rich RNA through their triple KH (hn RNP K homology) domain structures and are thought to carry out their function though direct protection of mRNA sites as well as through interactions with other RNA-binding proteins. We report the crystallographically derived structure of the third domain of αCP1 to 2.1 Å resolution. αCP1-KH3 assumes a classical type I KH domain fold with a triple-stranded β-sheet held against a three-helix cluster in a βααββα configuration. Its binding affinity to an RNA sequence from the 3′-untranslated region (3′-UTR) of androgen receptor mRNA was determined using surface plasmon resonance, giving a Kd of 4.37 μM, which is indicative of intermediate binding. A model of αCP1-KH3 with poly(C)-RNA was generated by homology to a recently reported RNA-bound KH domain structure and suggests the molecular basis for oligonucleotide binding and poly(C)-RNA specificity.
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Affiliation(s)
- M. Sidiqi
- School of Biomedical and Chemical Sciences, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
| | - J. A. Wilce
- School of Biomedical and Chemical Sciences, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
| | - J. P. Vivian
- School of Biomedical and Chemical Sciences, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
- School of Pharmacology and Medicine, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
| | - C. J. Porter
- School of Biomedical and Chemical Sciences, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
| | - A. Barker
- School of Biomedical and Chemical Sciences, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
- School of Pharmacology and Medicine, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
| | - P. J. Leedman
- Laboratory for Cancer Medicine, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
- Western Australian Institute for Medical Research, The University of Western AustraliaWA Australia 6009
| | - M. C. J. Wilce
- School of Biomedical and Chemical Sciences, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
- School of Pharmacology and Medicine, the UWA Centre for Medical Research, The University of Western AustraliaWA Australia 6009
- Western Australian Institute for Medical Research, The University of Western AustraliaWA Australia 6009
- To whom correspondence should be addressed at School of Pharmacology and Medicine and School of Biomedical and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Perth, Western Australia, 6009, Australia. Tel: +61 8 9346 2981; Fax: +61 8 9346 3469;
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40
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Klimek-Tomczak K, Wyrwicz LS, Jain S, Bomsztyk K, Ostrowski J. Characterization of hnRNP K protein-RNA interactions. J Mol Biol 2004; 342:1131-41. [PMID: 15351640 DOI: 10.1016/j.jmb.2004.07.099] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Revised: 07/23/2004] [Accepted: 07/29/2004] [Indexed: 11/16/2022]
Abstract
The heterogeneous nuclear ribonucleoprotein K protein is an RNA-binding protein found in several subcellular compartments where it is thought to be involved in signaling multiple processes that compose gene expression. K protein contains three K homology (KH) domains that mediate RNA-binding. We used a serial analysis of gene expression (SAGE)-based strategy, yeast three-hybrid screen, RNA pull-down assays and computational analysis to characterize K protein-associated RNAs. We demonstrate that K protein interacts with many sense and antisense nuclear and mitochondrial transcripts through both direct and indirect binding. The highly specific direct binding of transcripts to K protein is mediated by a consensus sequence comprising three C-rich patches. Structural analysis suggests a three-prong interaction model whereby each of the three KH domains binds one of the C-rich patches. Genome-wide and yeast three-hybrid clone analysis revealed that these sequences are located preferentially in the 3' untranslated regions, which are known to regulate mRNA translation and processing.
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Affiliation(s)
- Karolina Klimek-Tomczak
- Department of Gastroenterology, Medical Center for Postgraduate Education at Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland
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41
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Du Z, Ulyanov NB, Yu J, Andino R, James TL. NMR structures of loop B RNAs from the stem-loop IV domain of the enterovirus internal ribosome entry site: a single C to U substitution drastically changes the shape and flexibility of RNA. Biochemistry 2004; 43:5757-71. [PMID: 15134450 DOI: 10.1021/bi0363228] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 5'-untranslated region of positive-strand RNA viruses harbors many cis-acting RNA structural elements that are important for various viral processes such as replication, translation, and packaging of new virions. Among these is loop B RNA of the stem-loop IV domain within the internal ribosomal entry site (IRES) of enteroviruses, including Poliovirus type 1 (PV1). Studies on PV1 have shown that specific recognition of loop B by the first KH (hnRNP K homology) domain of cellular poly(rC)-binding protein 2 (PCBP2) is essential for efficient translation of the viral mRNA. Here we report the NMR solution structures of two representative sequence variants of enteroviral loop B RNA. The two RNA variants differ at only one position (C vs U) within a six-nucleotide asymmetric internal loop sequence that is the binding site for the PCBP2 KH1 domain. Surprisingly, the two RNAs are drastically different in the overall shape and local dynamics of the bulge region. The RNA with the 5'-AUCCCU bulge sequence adopts an overall L shape. Its bulge nucleotides, especially the last four, are highly flexible and not very well defined by NMR. The RNA with the 5'-AUUCCU bulge sequence adopts an overall U shape, and its bulge sequence exhibits only limited flexibility. A detailed analysis of the two RNA structures and their dynamic properties, as well as available sequence data and known KH domain-RNA complex structures, not only provides insights into how loop B RNA might be recognized by the PCBP2 KH1 domain but also suggests a possible correlation between structural flexibility and pre-existing structural features for protein recognition.
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Affiliation(s)
- Zhihua Du
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143-2280, USA
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42
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Du Z, Yu J, Chen Y, Andino R, James TL. Specific recognition of the C-rich strand of human telomeric DNA and the RNA template of human telomerase by the first KH domain of human poly(C)-binding protein-2. J Biol Chem 2004; 279:48126-34. [PMID: 15331611 DOI: 10.1074/jbc.m405371200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Poly(C)-binding proteins (PCBPs) constitute a family of nucleic acid-binding proteins that play important roles in a wide spectrum of regulatory mechanisms. The diverse functions of PCBPs are dependent on the ability of the PCBPs to recognize poly(C) sequences with high affinity and specificity. PCBPs contain three copies of KH (hnRNP K homology) domains, which are responsible for binding nucleic acids. We have determined the NMR structure of the first KH domain (KH1) from PCBP2. The PCBP2 KH1 domain adopts a structure with three alpha-helices packed against one side of a three-stranded antiparallel beta-sheet. Specific binding of PCBP2 KH1 to a number of poly(C) RNA and DNA sequences, including the C-rich strand of the human telomeric DNA repeat, the RNA template region of human telomerase, and regulatory recognition motifs in the poliovirus-1 5'-untranslated region, was established by monitoring chemical shift changes in protein (15)N-HSQC spectra. The nucleic acid binding groove was further mapped by chemical shift perturbation upon binding to a six-nucleotide human telomeric DNA. The binding groove is an alpha/beta platform formed by the juxtaposition of two alpha-helices, one beta-strand, and two flanking loops. Whereas there is a groove in common with all of the DNA and RNA binders with a hydrophobic floor accommodating a three-residue stretch of C residues, nuances in recognizing flanking residues are provided by hydrogen bonding partners in the KH domain. Specific interactions of PCBP2 KH1 with telomeric DNA and telomerase RNA suggest that PCBPs may participate in mechanisms involved in the regulation of telomere/telomerase functions.
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Affiliation(s)
- Zhihua Du
- Pharmaceutical Chemistry and Microbiology and Immunology, University of California, San Francisco, California 94143-2280, USA
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43
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Shimada K, Kondo K, Yamanishi K. Human herpesvirus 6 immediate-early 2 protein interacts with heterogeneous ribonucleoprotein K and casein kinase 2. Microbiol Immunol 2004; 48:205-10. [PMID: 15031534 DOI: 10.1111/j.1348-0421.2004.tb03507.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human herpesvirus 6 (HHV-6) immediate-early (IE) 2 protein (IE2) may play important but incompletely defined roles during infection. We used yeast two-hybrid screening to detect proteins interacting with HHV-6 IE2, and found heterogeneous nuclear ribonucleoprotein K (hnRNP K) and the beta subunit of casein kinase 2 (CK2beta) specifically interacted with HHV-6 IE2. The interactions were confirmed by GST pull-down assay, coimmunoprecipitation, and colocalization studies. These findings indicate that the HHV-6 IE2 protein interacts with hnRNP K and CK2, and these interactions may affect viral and cellular RNA transcription and translation in viral replication.
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Affiliation(s)
- Kazuya Shimada
- Department of Microbiology, Osaka University Medical School C1, Japan
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Abstract
RNA is an ancient and highly versatile molecule that plays fundamental roles in all living organisms. Its molecular functions range from being a mediator of genetic information to the regulation of essential cellular processes. These functions are often accomplished in close association with RNA binding proteins. Over the past few years, a considerable number of high-resolution three-dimensional structures of important protein-RNA complexes have been determined. Here, we wish to discuss recent examples and highlight principles and distinct features of single-stranded RNA recognition by conserved RNA binding domains.
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Affiliation(s)
- Ana C Messias
- Structural and Computational Biology, European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
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45
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Lindquist JN, Parsons CJ, Stefanovic B, Brenner DA. Regulation of alpha1(I) collagen messenger RNA decay by interactions with alphaCP at the 3'-untranslated region. J Biol Chem 2004; 279:23822-9. [PMID: 14973140 DOI: 10.1074/jbc.m314060200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Liver fibrosis is characterized by an increased deposition of extracellular matrix proteins, including collagen type I, by activated hepatic stellate cells (HSCs). Previous studies have shown that this increase is mediated primarily by a post-transcriptional mechanism. In particular, the RNA-binding protein alphaCP binds to the alpha1(I) collagen 3'-untranslated region (UTR) and stabilizes this RNA in activated, but not quiescent, HSCs. This study examines the role of alphaCP in the decay of transcripts containing the collagen 3'-UTR in extracts obtained from NIH fibroblasts and quiescent and activated HSCs. Using an in vitro decay system, alphaCP binding activity was competed out with the addition of wild type oligonucleotides, but not with mutant oligonucleotides. Competition of alphaCP binding activity increased the rate of decay of wild type transcripts containing the alphaCP 3'-UTR binding site, but not of transcripts containing a mutated binding site. Quiescent HSC extracts contain no alphaCP binding activity and have no difference in the rate of decay of transcripts with wild type and mutant binding sites for alphaCP. The addition of recombinant alphaCP was sufficient to increase the half-life of the wild type transcript, whereas that of the mutant transcript was minimally changed. In vitro decay assays performed with activated HSC extracts that contain alphaCP binding activity demonstrate a markedly reduced decay rate of wild type compared with mutant transcripts. In vivo small interfering RNA experiments targeting alphaCP showed a reduction of the binding activity of alphaCP and a concomitant reduction in intracellular levels of alpha1(I) collagen messenger RNA. In conclusion, this study demonstrates the direct role of alphaCP in the stabilization of alpha1(I) collagen messenger RNA by blocking RNA degradation in activated HSCs.
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Affiliation(s)
- Jeffrey N Lindquist
- Biochemistry and Biophysics and Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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46
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Qu Y, Guo JT, Olman V, Xu Y. Protein structure prediction using sparse dipolar coupling data. Nucleic Acids Res 2004; 32:551-61. [PMID: 14744980 PMCID: PMC373331 DOI: 10.1093/nar/gkh204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 12/10/2003] [Accepted: 12/10/2003] [Indexed: 12/17/2022] Open
Abstract
Residual dipolar coupling (RDC) represents one of the most exciting emerging NMR techniques for protein structure studies. However, solving a protein structure using RDC data alone is still a highly challenging problem. We report here a computer program, RDC-PROSPECT, for protein structure prediction based on a structural homolog or analog of the target protein in the Protein Data Bank (PDB), which best aligns with the (15)N-(1)H RDC data of the protein recorded in a single ordering medium. Since RDC-PROSPECT uses only RDC data and predicted secondary structure information, its performance is virtually independent of sequence similarity between a target protein and its structural homolog/analog, making it applicable to protein targets beyond the scope of current protein threading techniques. We have tested RDC-PROSPECT on all (15)N-(1)H RDC data (representing 43 proteins) deposited in the BioMagResBank (BMRB) database. The program correctly identified structural folds for 83.7% of the target proteins, and achieved an average alignment accuracy of 98.1% residues within a four-residue shift.
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Affiliation(s)
- Youxing Qu
- Computational Systems Biology Laboratory, Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
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47
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Abstract
Sam68 is one of the most studied members of the STAR family of RNA-binding proteins since its identification over a decade ago. Since its ascension into prominence, enormous progress has been made to unmask the link between the RNA-binding properties of Sam68 and the regulation of cellular processes including signal transduction, cell cycle regulation and tumorigenesis and RNA biogenesis in general. In this review we provide a detailed description of the functional domains of Sam68 and the possible biological roles that justify its superSTAR status.
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Affiliation(s)
- Kiven E Lukong
- Terry Fox Molecular Oncology Group and Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research, H3T 1E2 Québec, Canada
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48
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Meiler J, Baker D. Rapid protein fold determination using unassigned NMR data. Proc Natl Acad Sci U S A 2003; 100:15404-9. [PMID: 14668443 PMCID: PMC307580 DOI: 10.1073/pnas.2434121100] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2003] [Indexed: 11/18/2022] Open
Abstract
Experimental structure determination by x-ray crystallography and NMR spectroscopy is slow and time-consuming compared with the rate at which new protein sequences are being identified. NMR spectroscopy has the advantage of rapidly providing the structurally relevant information in the form of unassigned chemical shifts (CSs), intensities of NOESY crosspeaks [nuclear Overhauser effects (NOEs)], and residual dipolar couplings (RDCs), but use of these data are limited by the time and effort needed to assign individual resonances to specific atoms. Here, we develop a method for generating low-resolution protein structures by using unassigned NMR data that relies on the de novo protein structure prediction algorithm, rosetta [Simons, K. T., Kooperberg, C., Huang, E. & Baker, D. (1997) J. Mol. Biol. 268, 209-225] and a Monte Carlo procedure that searches for the assignment of resonances to atoms that produces the best fit of the experimental NMR data to a candidate 3D structure. A large ensemble of models is generated from sequence information alone by using rosetta, an optimal assignment is identified for each model, and the models are then ranked based on their fit with the NMR data assuming the identified assignments. The method was tested on nine protein sequences between 56 and 140 amino acids and published CS, NOE, and RDC data. The procedure yielded models with rms deviations between 3 and 6 A, and, in four of the nine cases, the partial assignments obtained by the method could be used to refine the structures to high resolution (0.6-1.8 A) by repeated cycles of structure generation guided by the partial assignments, followed by reassignment using the newly generated models.
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Affiliation(s)
- Jens Meiler
- Department of Biochemistry and Howard Hughes Medical Institute, University of Washington, PO Box 357350, Seattle, WA 98195-7350, USA
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49
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Mascioni A, Veglia G. Theoretical Analysis of Residual Dipolar Coupling Patterns in Regular Secondary Structures of Proteins. J Am Chem Soc 2003; 125:12520-6. [PMID: 14531696 DOI: 10.1021/ja0354824] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new approach to the interpretation of residual dipolar couplings for the regular secondary structures of proteins is presented. This paper deals with the analysis of the steric and chiral requirements of protein secondary structures and establishes a quantitative correlation between structure periodicity and the experimental values of the backbone residual dipolar couplings. Building on the recent interpretation of the periodicity of residual dipolar couplings in alpha-helices (i.e., "dipolar waves"), a general parametric equation for fitting the residual dipolar couplings of any regular secondary structure is derived. This equation interprets the modulation of the residual dipolar couplings' periodicity in terms of the secondary structure orientation with respect to an arbitrary reference frame, laying the groundwork for using backbone residual dipolar couplings as a fast tool for determining protein folding by NMR spectroscopy.
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Affiliation(s)
- Alessandro Mascioni
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA
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50
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Ramos A, Hollingworth D, Pastore A. The role of a clinically important mutation in the fold and RNA-binding properties of KH motifs. RNA (NEW YORK, N.Y.) 2003; 9:293-298. [PMID: 12592003 PMCID: PMC1370396 DOI: 10.1261/rna.2168503] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2002] [Accepted: 12/06/2002] [Indexed: 05/24/2023]
Abstract
We have investigated the role in the fold and RNA-binding properties of the KH modules of a hydrophobic to asparagine mutation of clinical importance in the fragile X syndrome. The mutation involves a well-conserved hydrophobic residue close to the N terminus of the second helix of the KH fold (alpha2(3) position). The effect of the mutation has been long debated: Although the mutant has been shown to disrupt the three-dimensional fold of several KH domains, the residue seems also to be directly involved in RNA binding, the main function of the KH module. Here we have used the KH3 of Nova-1, whose structure is known both in isolation and in an RNA complex, to study in detail the role of the alpha2(3) position. A detailed comparison of Nova KH3 structure with its RNA/KH complex and with other KH structures suggests a dual role for the alpha2(3) residue, which is involved both in stabilizing the hydrophobic core and in RNA contacts. We further show by nuclear magnetic resonance (NMR) studies in solution that L447 of Nova-1 in position alpha2(3) is in exchange in the absence of RNA, and becomes locked in a more rigid conformation only upon formation of an RNA complex. This implies that position alpha2(3) functions as a "gate" in the mechanism of RNA recognition of KH motifs based on the rigidification of the fold upon RNA binding.
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Affiliation(s)
- Andres Ramos
- National Institute for Medical Research, London NW7 1AA, UK
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