1
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Alavi Z, Casanova-Morales N, Quiroga-Roger D, Wilson CAM. Towards the understanding of molecular motors and its relationship with local unfolding. Q Rev Biophys 2024; 57:e7. [PMID: 38715547 DOI: 10.1017/s0033583524000052] [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] [Indexed: 06/14/2024]
Abstract
Molecular motors are machines essential for life since they convert chemical energy into mechanical work. However, the precise mechanism by which nucleotide binding, catalysis, or release of products is coupled to the work performed by the molecular motor is still not entirely clear. This is due, in part, to a lack of understanding of the role of force in the mechanical-structural processes involved in enzyme catalysis. From a mechanical perspective, one promising hypothesis is the Haldane-Pauling hypothesis which considers the idea that part of the enzymatic catalysis is strain-induced. It suggests that enzymes cannot be efficient catalysts if they are fully complementary to the substrates. Instead, they must exert strain on the substrate upon binding, using enzyme-substrate energy interaction (binding energy) to accelerate the reaction rate. A novel idea suggests that during catalysis, significant strain energy is built up, which is then released by a local unfolding/refolding event known as 'cracking'. Recent evidence has also shown that in catalytic reactions involving conformational changes, part of the heat released results in a center-of-mass acceleration of the enzyme, raising the possibility that the heat released by the reaction itself could affect the enzyme's integrity. Thus, it has been suggested that this released heat could promote or be linked to the cracking seen in proteins such as adenylate kinase (AK). We propose that the energy released as a consequence of ligand binding/catalysis is associated with the local unfolding/refolding events (cracking), and that this energy is capable of driving the mechanical work.
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Affiliation(s)
- Zahra Alavi
- Department of Physics, Loyola Marymount University, Los Angeles, CA, USA
| | | | - Diego Quiroga-Roger
- Biochemistry and Molecular Biology Department, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Christian A M Wilson
- Biochemistry and Molecular Biology Department, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
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2
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Mallimadugula UL, Galburt EA. Parallel path mechanisms lead to nonmonotonic force-velocity curves and an optimum load for molecular motor function. Phys Rev E 2022; 105:034405. [PMID: 35428051 DOI: 10.1103/physreve.105.034405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 02/15/2022] [Indexed: 06/14/2023]
Abstract
Molecular motors convert chemical potential energy into mechanical work and perform a great number of critical biological functions. Examples include the polymerization and manipulation of nucleic acids, the generation of cellular motility and contractility, the formation and maintenance of cell shape, and the transport of materials within cells. The mechanisms underlying these molecular machines are varied, but are almost always considered in the context of a single kinetic pathway that describes motor stepping. However, the multidimensional nature of protein energy landscapes suggests the possibility of multiple reaction pathways connecting two states. Here we investigate the properties of a hypothetical molecular motor able to utilize parallel translocation mechanisms. We explore motor velocity and force dependence as a function of the energy landscape of each path and reveal the potential for such a mechanism to result in negative differential conductance. More specifically, regimes exist where increasing opposing force leads to increased velocity and an optimum load for motor function. We explore how the presence of this optimum depends on the rates of the individual paths and show that the distribution of stepping times characterized by the randomness parameter may be used to test for parallel path mechanisms. Last, we caution that experimental data consisting solely of measurements of velocity as a function of ATP concentration and force cannot be used to eliminate the possibility of such a parallel path mechanism.
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Affiliation(s)
- Upasana L Mallimadugula
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63108, USA
| | - Eric A Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, Missouri 63108, USA
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3
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Trindade F, Barros AS, Silva J, Vlahou A, Falcão-Pires I, Guedes S, Vitorino C, Ferreira R, Leite-Moreira A, Amado F, Vitorino R. Mining the Biomarker Potential of the Urine Peptidome: From Amino Acids Properties to Proteases. Int J Mol Sci 2021; 22:5940. [PMID: 34073067 PMCID: PMC8197949 DOI: 10.3390/ijms22115940] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 12/11/2022] Open
Abstract
Native biofluid peptides offer important information about diseases, holding promise as biomarkers. Particularly, the non-invasive nature of urine sampling, and its high peptide concentration, make urine peptidomics a useful strategy to study the pathogenesis of renal conditions. Moreover, the high number of detectable peptides as well as their specificity set the ground for the expansion of urine peptidomics to the identification of surrogate biomarkers for extra-renal diseases. Peptidomics further allows the prediction of proteases (degradomics), frequently dysregulated in disease, providing a complimentary source of information on disease pathogenesis and biomarkers. Then, what does urine peptidomics tell us so far? In this paper, we appraise the value of urine peptidomics in biomarker research through a comprehensive analysis of all datasets available to date. We have mined > 50 papers, addressing > 30 different conditions, comprising > 4700 unique peptides. Bioinformatic tools were used to reanalyze peptide profiles aiming at identifying disease fingerprints, to uncover hidden disease-specific peptides physicochemical properties and to predict the most active proteases associated with their generation. The molecular patterns found in this study may be further validated in the future as disease biomarker not only for kidney diseases but also for extra-renal conditions, as a step forward towards the implementation of a paradigm of predictive, preventive and personalized (3P) medicine.
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Affiliation(s)
- Fábio Trindade
- UnIC—Cardiovascular Research and Development Centre, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (A.S.B.); (I.F.-P.); (A.L.-M.)
| | - António S. Barros
- UnIC—Cardiovascular Research and Development Centre, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (A.S.B.); (I.F.-P.); (A.L.-M.)
| | - Jéssica Silva
- iBiMED—Department of Medical Sciences, Institute of Biomedicine, University of Aveiro, 3810-193 Aveiro, Portugal;
| | - Antonia Vlahou
- Biotechnology Division, Biomedical Research Foundation of the Academy of Athens, 115 27 Athens, Greece;
| | - Inês Falcão-Pires
- UnIC—Cardiovascular Research and Development Centre, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (A.S.B.); (I.F.-P.); (A.L.-M.)
| | - Sofia Guedes
- LAQV-REQUIMTE, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal; (S.G.); (R.F.); (F.A.)
| | - Carla Vitorino
- Faculty of Pharmacy, University of Coimbra, 3000-548 Coimbra, Portugal;
- Coimbra Chemistry Centre, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
- Center for Neurosciences and Cell Biology (CNC), University of Coimbra, 3004-504 Coimbra, Portugal
| | - Rita Ferreira
- LAQV-REQUIMTE, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal; (S.G.); (R.F.); (F.A.)
| | - Adelino Leite-Moreira
- UnIC—Cardiovascular Research and Development Centre, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (A.S.B.); (I.F.-P.); (A.L.-M.)
| | - Francisco Amado
- LAQV-REQUIMTE, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal; (S.G.); (R.F.); (F.A.)
| | - Rui Vitorino
- UnIC—Cardiovascular Research and Development Centre, Department of Surgery and Physiology, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal; (A.S.B.); (I.F.-P.); (A.L.-M.)
- iBiMED—Department of Medical Sciences, Institute of Biomedicine, University of Aveiro, 3810-193 Aveiro, Portugal;
- LAQV-REQUIMTE, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal; (S.G.); (R.F.); (F.A.)
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4
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Barba-Aliaga M, Alepuz P, Pérez-Ortín JE. Eukaryotic RNA Polymerases: The Many Ways to Transcribe a Gene. Front Mol Biosci 2021; 8:663209. [PMID: 33968992 PMCID: PMC8097091 DOI: 10.3389/fmolb.2021.663209] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 03/09/2021] [Indexed: 01/04/2023] Open
Abstract
In eukaryotic cells, three nuclear RNA polymerases (RNA pols) carry out the transcription from DNA to RNA, and they all seem to have evolved from a single enzyme present in the common ancestor with archaea. The multiplicity of eukaryotic RNA pols allows each one to remain specialized in the synthesis of a subset of transcripts, which are different in the function, length, cell abundance, diversity, and promoter organization of the corresponding genes. We hypothesize that this specialization of RNA pols has conditioned the evolution of the regulatory mechanisms used to transcribe each gene subset to cope with environmental changes. We herein present the example of the homeostatic regulation of transcript levels versus changes in cell volume. We propose that the diversity and instability of messenger RNAs, transcribed by RNA polymerase II, have conditioned the appearance of regulatory mechanisms based on different gene promoter strength and mRNA stability. However, for the regulation of ribosomal RNA levels, which are very stable and transcribed mainly by RNA polymerase I from only one promoter, different mechanisms act based on gene copy variation, and a much simpler regulation of the synthesis rate.
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Affiliation(s)
- Marina Barba-Aliaga
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, València, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, València, Spain
| | - Paula Alepuz
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, València, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, València, Spain
| | - José E Pérez-Ortín
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, València, Spain.,Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universitat de València, València, Spain
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5
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Nair SP, Sharma RK. Heat shock proteins and their expression in primary murine cardiac cell populations during ischemia and reperfusion. Mol Cell Biochem 2019; 464:21-26. [DOI: 10.1007/s11010-019-03645-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/23/2019] [Indexed: 10/25/2022]
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6
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Manavella PA, Yang SW, Palatnik J. Keep calm and carry on: miRNA biogenesis under stress. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:832-843. [PMID: 31025462 DOI: 10.1111/tpj.14369] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/09/2019] [Accepted: 04/23/2019] [Indexed: 05/20/2023]
Abstract
MicroRNAs (miRNAs) are major post-transcriptional regulators of gene expression. Their biogenesis relies on the cleavage of longer precursors by a nuclear localized processing machinery. The evolutionary preference of plant miRNAs to silence transcription factors turned these small molecules into key actors during growth and adaptive responses. Furthermore, during their life cycle plants are subject to changes in the environmental conditions surrounding them. In order to face these changes, plants display unique adaptive capacities based on an enormous developmental plasticity, where miRNAs play central roles. Many individual miRNAs have been shown to modulate the plant response to different environmental cues and stresses. In the last few years, increasing evidence has shown that not only individual genes encoding miRNAs but also the miRNA pathway as a whole is subject to regulation in response to external stimulus. In this review, we discuss the current knowledge about the miRNA pathway. We dissect the pathway to analyze the events leading to the generation of these small RNAs and emphasize the regulation of core components of the miRNA biogenesis machinery.
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Affiliation(s)
- Pablo A Manavella
- Instituto de Agrobiotecnología del Litoral (IAL, CONICET-UNL-FBCB), Santa Fe, 3000, Argentina
| | - Seong W Yang
- Department of Systems Biology, Institute of Life Science and Biotechnology, Yonsei University, Seoul, Korea
| | - Javier Palatnik
- Instituto de Biología Molecular y Celular de Rosario (IBR, CONICET-UNR), Rosario, 2000, Argentina
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7
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Using Single-Molecule Chemo-Mechanical Unfolding to Simultaneously Probe Multiple Structural Parameters in Protein Folding. Methods Protoc 2019; 2:mps2020032. [PMID: 31164612 PMCID: PMC6632164 DOI: 10.3390/mps2020032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/10/2019] [Accepted: 04/15/2019] [Indexed: 11/28/2022] Open
Abstract
While single-molecule force spectroscopy has greatly advanced the study of protein folding, there are limitations to what can be learned from studying the effect of force alone. We developed a novel technique, chemo-mechanical unfolding, that combines multiple perturbants—force and chemical denaturant—to more fully characterize the folding process by simultaneously probing multiple structural parameters—the change in end-to-end distance, and solvent accessible surface area. Here, we describe the theoretical background, experimental design, and data analysis for chemo-mechanical unfolding experiments probing protein folding thermodynamics and kinetics. This technique has been applied to characterize parallel protein folding pathways, the protein denatured state, protein folding on the ribosome, and protein folding intermediates.
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8
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Casanova-Morales N, Quiroga-Roger D, Alfaro-Valdés HM, Alavi Z, Lagos-Espinoza MIA, Zocchi G, Wilson CAM. Mechanical properties of BiP protein determined by nano-rheology. Protein Sci 2019; 27:1418-1426. [PMID: 29696702 DOI: 10.1002/pro.3432] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 04/06/2018] [Accepted: 04/19/2018] [Indexed: 02/01/2023]
Abstract
Immunoglobulin Binding Protein (BiP) is a chaperone and molecular motor belonging to the Hsp70 family, involved in the regulation of important biological processes such as synthesis, folding and translocation of proteins in the Endoplasmic Reticulum. BiP has two highly conserved domains: the N-terminal Nucleotide-Binding Domain (NBD), and the C-terminal Substrate-Binding Domain (SBD), connected by a hydrophobic linker. ATP binds and it is hydrolyzed to ADP in the NBD, and BiP's extended polypeptide substrates bind in the SBD. Like many molecular motors, BiP function depends on both structural and catalytic properties that may contribute to its performance. One novel approach to study the mechanical properties of BiP considers exploring the changes in the viscoelastic behavior upon ligand binding, using a technique called nano-rheology. This technique is essentially a traditional rheology experiment, in which an oscillatory force is directly applied to the protein under study, and the resulting average deformation is measured. Our results show that the folded state of the protein behaves like a viscoelastic material, getting softer when it binds nucleotides- ATP, ADP, and AMP-PNP-, but stiffer when binding HTFPAVL peptide substrate. Also, we observed that peptide binding dramatically increases the affinity for ADP, decreasing it dissociation constant (KD ) around 1000 times, demonstrating allosteric coupling between SBD and NBD domains.
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Affiliation(s)
- Nathalie Casanova-Morales
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, 8380494, Chile
| | - Diego Quiroga-Roger
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, 8380494, Chile
| | - Hilda M Alfaro-Valdés
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, 8380494, Chile
| | - Zahra Alavi
- Department of Physics and Astronomy, University of California - Los Angeles, Los Angeles, California, 90095, US.,Department of Physics, Loyola Marymount University, Los Angeles, California, 90045, US
| | - Miguel I A Lagos-Espinoza
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, 8380494, Chile
| | - Giovanni Zocchi
- Department of Physics and Astronomy, University of California - Los Angeles, Los Angeles, California, 90095, US
| | - Christian A M Wilson
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, 8380494, Chile
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9
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Niño SA, Morales-Martínez A, Chi-Ahumada E, Carrizales L, Salgado-Delgado R, Pérez-Severiano F, Díaz-Cintra S, Jiménez-Capdeville ME, Zarazúa S. Arsenic Exposure Contributes to the Bioenergetic Damage in an Alzheimer's Disease Model. ACS Chem Neurosci 2019; 10:323-336. [PMID: 30141907 DOI: 10.1021/acschemneuro.8b00278] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Worldwide, every year there is an increase in the number of people exposed to inorganic arsenic (iAs) via drinking water. Human populations present impaired cognitive function as a result of prenatal and childhood iAs exposure, while studies in animal models demonstrate neurobehavioral deficits accompanied by neurotransmitter, protein, and enzyme alterations. Similar impairments have been observed in close association with Alzheimer's disease (AD). In order to determine whether iAs promotes the pathophysiological progress of AD, we used the 3xTgAD mouse model. Mice were exposed to iAs in drinking water from gestation until 6 months (As-3xTgAD group) and compared with control animals without arsenic (3xTgAD group). We investigated the behavior phenotype on a test battery (circadian rhythm, locomotor behavior, Morris water maze, and contextual fear conditioning). Adenosine triphosphate (ATP), reactive oxygen species, lipid peroxidation, and respiration rates of mitochondria were evaluated, antioxidant components were detected by immunoblots, and immunohistochemical studies were performed to reveal AD markers. As-3xTgAD displayed alterations in their circadian rhythm and exhibited longer freezing time and escape latencies compared to the control group. The bioenergetic profile revealed decreased ATP levels accompanied by the decline of complex I, and an oxidant state in the hippocampus. On the other hand, the cortex showed no changes of oxidant stress and complex I; however, the antioxidant response was increased. Higher immunopositivity to amyloid isoforms and to phosphorylated tau was observed in frontal cortex and hippocampus of exposed animals. In conclusion, mitochondrial dysfunction may be one of the triggering factors through which chronic iAs exposure exacerbates brain AD-like pathology.
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Affiliation(s)
- Sandra Aurora Niño
- Laboratorio de Neurotoxicología, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava 6, CP 78210 San Luis Potosí, SLP, México
| | - Adriana Morales-Martínez
- Departamento de Neuroquímica, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, Insurgentes Sur 3877, CP 14269, México D.F., México
| | - Erika Chi-Ahumada
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosi, Av. Venustiano Carranza 2405, CP 78210 San Luis Potosí, SLP, México
| | - Leticia Carrizales
- Centro de Investigación Aplicada en Ambiente y Salud, CIACYT, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Av. Venustiano Carranza 2405, CP 78210 San Luis Potosí, SLP, México
| | - Roberto Salgado-Delgado
- Facultad de Ciencias, Universidad Autónoma de San Luis Potosí, Av. Salvador Nava Martínez S/N, CP 78290 San Luis Potosí, SLP, Mexico
| | - Francisca Pérez-Severiano
- Departamento de Neuroquímica, Instituto Nacional de Neurología y Neurocirugía “Manuel Velasco Suárez”, Insurgentes Sur 3877, CP 14269, México D.F., México
| | - Sofía Díaz-Cintra
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, CP 76230 Juriquilla, Querétaro, México
| | - María E. Jiménez-Capdeville
- Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosi, Av. Venustiano Carranza 2405, CP 78210 San Luis Potosí, SLP, México
| | - Sergio Zarazúa
- Laboratorio de Neurotoxicología, Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Av. Manuel Nava 6, CP 78210 San Luis Potosí, SLP, México
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10
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The Autophagy-Lysosomal Pathways and Their Emerging Roles in Modulating Proteostasis in Tumors. Cells 2018; 8:cells8010004. [PMID: 30577555 PMCID: PMC6356230 DOI: 10.3390/cells8010004] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 12/12/2022] Open
Abstract
In normal physiological condition, the maintenance of cellular proteostasis is a prerequisite for cell growth, functioning, adapting to changing micro-environments, and responding to extracellular stress. Cellular proteostasis is maintained by specific proteostasis networks (PNs) to prevent protein misfolding, aggregating, and accumulating in subcellular compartments. Commonly, the PNs are composed of protein synthesis, molecular chaperones, endoplasmic reticulum (ER), unfolded protein response (UPR), stress response pathways (SRPs), secretions, ubiquitin proteasome system (UPS), and autophagy-lysosomal pathways (ALPs). Although great efforts have been made to explore the underlying detailed mechanisms of proteostasis, there are many questions remain to explore, especially in proteostasis regulated by the ALPs. Proteostasis out-off-balance is correlated with various human diseases such as diabetes, stroke, inflammation, hypertension, pulmonary fibrosis, and Alzheimer’s disease. Enhanced regulation of PNs is observed in tumors, thereby indicating that proteostasis may play a pivotal role in tumorigenesis and cancer development. Recently, inhibitors targeting the UPS have shown to be failed in solid tumor treatment. However, there is growing evidence showing that the ALPs play important roles in regulation of proteostasis alone or with a crosstalk with other PNs in tumors. In this review, we provide insights into the proteostatic process and how it is regulated by the ALPs, such as macroautophagy, aggrephagy, chaperone-mediated autophagy, microautophagy, as well as mitophagy during tumor development.
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11
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Peng S, Sun R, Wang W, Chen C. Single-molecule FRET studies on interactions between elongation factor 4 (LepA) and ribosomes. CHINESE CHEM LETT 2018. [DOI: 10.1016/j.cclet.2017.12.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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12
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ATPase and Protease Domain Movements in the Bacterial AAA+ Protease FtsH Are Driven by Thermal Fluctuations. J Mol Biol 2018; 430:4592-4602. [PMID: 30044948 DOI: 10.1016/j.jmb.2018.07.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/10/2018] [Accepted: 07/17/2018] [Indexed: 01/27/2023]
Abstract
AAA+ proteases are essential players in cellular pathways of protein degradation. Elucidating their conformational behavior is key for understanding their reaction mechanism and, importantly, for elaborating our understanding of mutation-induced protease deficiencies. Here, we study the structural dynamics of the Thermotoga maritima AAA+ hexameric ring metalloprotease FtsH (TmFtsH). Using a single-molecule Förster resonance energy transfer approach to monitor ATPase and protease inter-domain conformational changes in real time, we show that TmFtsH-even in the absence of nucleotide-is a highly dynamic protease undergoing sequential transitions between five states on the second timescale. Addition of ATP does not influence the number of states or change the timescale of domain motions but affects the state occupancy distribution leading to an inter-domain compaction. These findings suggest that thermal energy, but not chemical energy, provides the major driving force for conformational switching, while ATP, through a state reequilibration, introduces directionality into this process. The TmFtsH A359V mutation, a homolog of the human pathogenic A510V mutation of paraplegin (SPG7) causing hereditary spastic paraplegia, does not affect the dynamic behavior of the protease but impairs the ATP-coupled domain compaction and, thus, may account for protease malfunctioning and pathogenesis in hereditary spastic paraplegia.
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13
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Schönfelder J, Alonso-Caballero A, De Sancho D, Perez-Jimenez R. The life of proteins under mechanical force. Chem Soc Rev 2018; 47:3558-3573. [PMID: 29473060 DOI: 10.1039/c7cs00820a] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although much of our understanding of protein folding comes from studies of isolated protein domains in bulk, in the cellular environment the intervention of external molecular machines is essential during the protein life cycle. During the past decade single molecule force spectroscopy techniques have been extremely useful to deepen our understanding of these interventional molecular processes, as they allow for monitoring and manipulating mechanochemical events in individual protein molecules. Here, we review some of the critical steps in the protein life cycle, starting with the biosynthesis of the nascent polypeptide chain in the ribosome, continuing with the folding supported by chaperones and the translocation into different cell compartments, and ending with proteolysis in the proteasome. Along these steps, proteins experience molecular forces often combined with chemical transformations, affecting their folding and structure, which are measured or mimicked in the laboratory by the application of force with a single molecule apparatus. These mechanochemical reactions can potentially be used as targets for fighting against diseases. Inspired by these insightful experiments, we devise an outlook on the emerging field of mechanopharmacology, which reflects an alternative paradigm for drug design.
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14
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Yang D, Wong WP. Repurposing a Benchtop Centrifuge for High-Throughput Single-Molecule Force Spectroscopy. Methods Mol Biol 2018; 1665:353-366. [PMID: 28940079 PMCID: PMC5640162 DOI: 10.1007/978-1-4939-7271-5_19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We present high-throughput single-molecule manipulation using a benchtop centrifuge, overcoming limitations common in other single-molecule approaches such as high cost, low throughput, technical difficulty, and strict infrastructure requirements. An inexpensive and compact Centrifuge Force Microscope (CFM) adapted to a commercial centrifuge enables use by nonspecialists, and integration with DNA nanoswitches facilitates both reliable measurements and repeated molecular interrogation. Here, we provide detailed protocols for constructing the CFM, creating DNA nanoswitch samples, and carrying out single-molecule force measurements.
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Affiliation(s)
- Darren Yang
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Wesley P. Wong
- Program in Cellular and Molecular Medicine, Boston Children’s Hospital, Boston, MA 02115, USA,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
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15
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Mena A, Medina DA, García-Martínez J, Begley V, Singh A, Chávez S, Muñoz-Centeno MC, Pérez-Ortín JE. Asymmetric cell division requires specific mechanisms for adjusting global transcription. Nucleic Acids Res 2017; 45:12401-12412. [PMID: 29069448 PMCID: PMC5716168 DOI: 10.1093/nar/gkx974] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/10/2017] [Indexed: 12/19/2022] Open
Abstract
Most cells divide symmetrically into two approximately identical cells. There are many examples, however, of asymmetric cell division that can generate sibling cell size differences. Whereas physical asymmetric division mechanisms and cell fate consequences have been investigated, the specific problem caused by asymmetric division at the transcription level has not yet been addressed. In symmetrically dividing cells the nascent transcription rate increases in parallel to cell volume to compensate it by keeping the actual mRNA synthesis rate constant. This cannot apply to the yeast Saccharomyces cerevisiae, where this mechanism would provoke a never-ending increasing mRNA synthesis rate in smaller daughter cells. We show here that, contrarily to other eukaryotes with symmetric division, budding yeast keeps the nascent transcription rates of its RNA polymerases constant and increases mRNA stability. This control on RNA pol II-dependent transcription rate is obtained by controlling the cellular concentration of this enzyme.
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Affiliation(s)
- Adriana Mena
- Departamento de Bioquímica y Biología Molecular and E.R.I. Biotecmed, Universitat de València, Dr. Moliner, 50, Burjassot 46100, Valencia, Spain
| | - Daniel A Medina
- Departamento de Bioquímica y Biología Molecular and E.R.I. Biotecmed, Universitat de València, Dr. Moliner, 50, Burjassot 46100, Valencia, Spain
| | - José García-Martínez
- Departamento de Genética and E.R.I. Biotecmed, Universitat de València, Dr. Moliner, 50, Burjassot 46100, Valencia, Spain
| | - Victoria Begley
- Departamento de Genética, Universidad de Sevilla and Instituto de Biomedicina de Sevilla (IBiS), Hospital Virgen del Rocío-CSIC-Universidad de Sevilla, 41013 Sevilla, Spain
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE 19716, USA
| | - Sebastián Chávez
- Departamento de Genética, Universidad de Sevilla and Instituto de Biomedicina de Sevilla (IBiS), Hospital Virgen del Rocío-CSIC-Universidad de Sevilla, 41013 Sevilla, Spain
| | - Mari C Muñoz-Centeno
- Departamento de Genética, Universidad de Sevilla and Instituto de Biomedicina de Sevilla (IBiS), Hospital Virgen del Rocío-CSIC-Universidad de Sevilla, 41013 Sevilla, Spain
| | - José E Pérez-Ortín
- Departamento de Bioquímica y Biología Molecular and E.R.I. Biotecmed, Universitat de València, Dr. Moliner, 50, Burjassot 46100, Valencia, Spain
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16
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Peng S, Wang W, Chen C. Breaking the Concentration Barrier for Single-Molecule Fluorescence Measurements. Chemistry 2017; 24:1002-1009. [DOI: 10.1002/chem.201704065] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Sijia Peng
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, and Beijing Advanced Innovation Center for Structural Biology; Tsinghua University; Beijing, 100084 P.R. China
| | - Wenjuan Wang
- School of Life Sciences and Technology Center for Protein Sciences; Tsinghua University; Beijing, 100084 P.R. China
| | - Chunlai Chen
- School of Life Sciences, Tsinghua-Peking Joint Center for Life Sciences, and Beijing Advanced Innovation Center for Structural Biology; Tsinghua University; Beijing, 100084 P.R. China
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17
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Krochmal M, Kontostathi G, Magalhães P, Makridakis M, Klein J, Husi H, Leierer J, Mayer G, Bascands JL, Denis C, Zoidakis J, Zürbig P, Delles C, Schanstra JP, Mischak H, Vlahou A. Urinary peptidomics analysis reveals proteases involved in diabetic nephropathy. Sci Rep 2017; 7:15160. [PMID: 29123184 PMCID: PMC5680307 DOI: 10.1038/s41598-017-15359-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 10/24/2017] [Indexed: 12/13/2022] Open
Abstract
Mechanisms underlying the onset and progression of nephropathy in diabetic patients are not fully elucidated. Deregulation of proteolytic systems is a known path leading to disease manifestation, therefore we hypothesized that proteases aberrantly expressed in diabetic nephropathy (DN) may be involved in the generation of DN-associated peptides in urine. We compared urinary peptide profiles of DN patients (macroalbuminuric, n = 121) to diabetic patients with no evidence of DN (normoalbuminuric, n = 118). 302 sequenced, differentially expressed peptides (adjusted p-value < 0.05) were analysed with the Proteasix tool predicting proteases potentially involved in their generation. Activity change was estimated based on the change in abundance of the investigated peptides. Predictions were correlated with transcriptomics (Nephroseq) and relevant protein expression data from the literature. This analysis yielded seventeen proteases, including multiple forms of MMPs, cathepsin D and K, kallikrein 4 and proprotein convertases. The activity of MMP-2 and MMP-9, predicted to be decreased in DN, was investigated using zymography in a DN mouse model confirming the predictions. Collectively, this proof-of-concept study links urine peptidomics to molecular changes at the tissue level, building hypotheses for further investigation in DN and providing a workflow with potential applications to other diseases.
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Affiliation(s)
| | | | - Pedro Magalhães
- Mosaiques Diagnostics GmbH, Hannover, Germany
- Department of Pediatric Nephrology, Hannover Medical School, Hannover, Germany
| | | | - Julie Klein
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Institut of Cardiovascular and Metabolic Disease, Toulouse, France
- Université Toulouse III Paul-Sabatier, Toulouse, France
| | - Holger Husi
- Department of Diabetes and Cardiovascular Science, University of the Highlands and Islands, Centre for Health Science, Inverness, IV2 3JH, UK
| | - Johannes Leierer
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University Innsbruck, Innsbruck, Austria
| | - Gert Mayer
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University Innsbruck, Innsbruck, Austria
| | - Jean-Loup Bascands
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1188 - Université de La, Réunion, France
| | - Colette Denis
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Institut of Cardiovascular and Metabolic Disease, Toulouse, France
- Université Toulouse III Paul-Sabatier, Toulouse, France
| | - Jerome Zoidakis
- Biomedical Research Foundation Academy of Athens, Athens, Greece
| | | | - Christian Delles
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow, G12 8TA, UK
| | - Joost P Schanstra
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1048, Institut of Cardiovascular and Metabolic Disease, Toulouse, France
- Université Toulouse III Paul-Sabatier, Toulouse, France
| | - Harald Mischak
- Mosaiques Diagnostics GmbH, Hannover, Germany
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow, G12 8TA, UK
| | - Antonia Vlahou
- Biomedical Research Foundation Academy of Athens, Athens, Greece.
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18
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Exploring the Denatured State Ensemble by Single-Molecule Chemo-Mechanical Unfolding: The Effect of Force, Temperature, and Urea. J Mol Biol 2017; 430:450-464. [PMID: 28782558 DOI: 10.1016/j.jmb.2017.07.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 07/29/2017] [Accepted: 07/31/2017] [Indexed: 11/22/2022]
Abstract
While it is widely appreciated that the denatured state of a protein is a heterogeneous conformational ensemble, there is still debate over how this ensemble changes with environmental conditions. Here, we use single-molecule chemo-mechanical unfolding, which combines force and urea using the optical tweezers, together with traditional protein unfolding studies to explore how perturbants commonly used to unfold proteins (urea, force, and temperature) affect the denatured-state ensemble. We compare the urea m-values, which report on the change in solvent accessible surface area for unfolding, to probe the denatured state as a function of force, temperature, and urea. We find that while the urea- and force-induced denatured states expose similar amounts of surface area, the denatured state at high temperature and low urea concentration is more compact. To disentangle these two effects, we use destabilizing mutations that shift the Tm and Cm. We find that the compaction of the denatured state is related to changing temperature as the different variants of acyl-coenzyme A binding protein have similar m-values when they are at the same temperature but different urea concentration. These results have important implications for protein folding and stability under different environmental conditions.
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19
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Abstract
The elucidation of the genetic code remains among the most influential discoveries in biology. While innumerable studies have validated the general universality of the code and its value in predicting and analyzing protein coding sequences, established and emerging work has also suggested that full genome decryption may benefit from a greater consideration of a codon's neighborhood within an mRNA than has been broadly applied. This Review examines the evidence for context cues in translation, with a focus on several recent studies that reveal broad roles for mRNA context in programming translation start sites, the rate of translation elongation, and stop codon identity.
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20
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Benet M, Miguel A, Carrasco F, Li T, Planells J, Alepuz P, Tordera V, Pérez-Ortín JE. Modulation of protein synthesis and degradation maintains proteostasis during yeast growth at different temperatures. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:794-802. [PMID: 28461260 DOI: 10.1016/j.bbagrm.2017.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 04/07/2017] [Accepted: 04/18/2017] [Indexed: 02/03/2023]
Abstract
To understand how cells regulate each step in the flow of gene expression is one of the most fundamental goals in molecular biology. In this work, we have investigated several protein turnover-related steps in the context of gene expression regulation in response to changes in external temperature in model yeast Saccharomyces cerevisiae. We have found that the regulation of protein homeostasis is stricter than mRNA homeostasis. Although global translation and protein degradation rates are found to increase with temperature, the increase of the catalytic activity of ribosomes is higher than the global translation rate suggesting that yeast cells adapt the amount of translational machinery to the constraints imposed by kinetics in order to minimize energy costs. Even though the transcriptional machinery is subjected to the same constraints, we observed interesting differences between transcription and translation, which may be related to the different energy costs of the two processes as well as the differential functions of mRNAs and proteins.
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Affiliation(s)
- Marta Benet
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - Ana Miguel
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - Fany Carrasco
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - Tianlu Li
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - Jordi Planells
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - Paula Alepuz
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - Vicente Tordera
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain
| | - José E Pérez-Ortín
- Departamento de Bioquímica y Biología Molecular and ERI Biotecmed, Facultad de Biológicas, Universitat de València, C/ Dr. Moliner 50, E46100 Burjassot, Spain.
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21
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Mishra RC, Grover A. Constitutive over-expression of rice ClpD1 protein enhances tolerance to salt and desiccation stresses in transgenic Arabidopsis plants. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2016; 250:69-78. [PMID: 27457985 DOI: 10.1016/j.plantsci.2016.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/04/2016] [Accepted: 06/02/2016] [Indexed: 06/06/2023]
Abstract
Caseinolytic proteases (Clps) perform the important role of removing protein aggregates from cells, which can otherwise prove to be highly toxic. ClpD system is a two-component protease complex composed of a regulatory ATPase module ClpD and a proteolytic component ClpP. Under desiccation stress condition, rice ClpD1 (OsClpD1) gene encoding for the regulatory subunit, was represented by four variant transcripts differing mainly in the expanse of their N-terminal amino acids. These transcripts were expressed in a differential manner in response to salt, mannitol and polyethylene glycol stresses in rice. Purified OsClpD1.3 protein exhibited intrinsic chaperone activity, shown using citrate synthase as substrate. Arabidopsis (Col-0) plants over-expressing OsClpD1.3 open reading frame downstream to CaMV35S promoter (ClpD1.3 plants) showed higher tolerance to salt and desiccation stresses as compared to wild type plants. ClpD1.3 seedlings also showed enhanced growth during the early stages of seed germination under unstressed, control conditions. The free proline levels and starch breakdown activities were higher in the ClpD1.3 seedlings as compared to the wild type Arabidopsis seedlings. It thus emerges that increasing the potential of ClpD1 chaperoning activity may be of advantage in protection against abiotic stresses.
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Affiliation(s)
- Ratnesh Chandra Mishra
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India
| | - Anil Grover
- Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
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22
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Faure G, Ogurtsov AY, Shabalina SA, Koonin EV. Role of mRNA structure in the control of protein folding. Nucleic Acids Res 2016; 44:10898-10911. [PMID: 27466388 PMCID: PMC5159526 DOI: 10.1093/nar/gkw671] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 07/12/2016] [Accepted: 07/14/2016] [Indexed: 11/13/2022] Open
Abstract
Specific structures in mRNA modulate translation rate and thus can affect protein folding. Using the protein structures from two eukaryotes and three prokaryotes, we explore the connections between the protein compactness, inferred from solvent accessibility, and mRNA structure, inferred from mRNA folding energy (ΔG). In both prokaryotes and eukaryotes, the ΔG value of the most stable 30 nucleotide segment of the mRNA (ΔGmin) strongly, positively correlates with protein solvent accessibility. Thus, mRNAs containing exceptionally stable secondary structure elements typically encode compact proteins. The correlations between ΔG and protein compactness are much more pronounced in predicted ordered parts of proteins compared to the predicted disordered parts, indicative of an important role of mRNA secondary structure elements in the control of protein folding. Additionally, ΔG correlates with the mRNA length and the evolutionary rate of synonymous positions. The correlations are partially independent and were used to construct multiple regression models which explain about half of the variance of protein solvent accessibility. These findings suggest a model in which the mRNA structure, particularly exceptionally stable RNA structural elements, act as gauges of protein co-translational folding by reducing ribosome speed when the nascent peptide needs time to form and optimize the core structure.
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Affiliation(s)
- Guilhem Faure
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Aleksey Y Ogurtsov
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Svetlana A Shabalina
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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23
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Multiplexed single-molecule force spectroscopy using a centrifuge. Nat Commun 2016; 7:11026. [PMID: 26984516 PMCID: PMC4800429 DOI: 10.1038/ncomms11026] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/12/2016] [Indexed: 11/30/2022] Open
Abstract
We present a miniature centrifuge force microscope (CFM) that repurposes a benchtop centrifuge for high-throughput single-molecule experiments with high-resolution particle tracking, a large force range, temperature control and simple push-button operation. Incorporating DNA nanoswitches to enable repeated interrogation by force of single molecular pairs, we demonstrate increased throughput, reliability and the ability to characterize population heterogeneity. We perform spatiotemporally multiplexed experiments to collect 1,863 bond rupture statistics from 538 traceable molecular pairs in a single experiment, and show that 2 populations of DNA zippers can be distinguished using per-molecule statistics to reduce noise. Single molecule force spectroscopy (SMFS) has limitations in throughput and the ability to repeatedly interrogate single bonds. Here the authors repurpose a benchtop centrifuge and use DNA nanoswitches to enable high throughput SMFS capable of repeatedly measuring forces of single molecular pairs.
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24
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Abstract
Baseline physiological function of the mammalian heart is under the constant threat of environmental or intrinsic pathological insults. Cardiomyocyte proteins are thus subject to unremitting pressure to function optimally, and this depends on them assuming and maintaining proper conformation. This review explores the multiple defenses a cell may use for its proteins to assume and maintain correct protein folding and conformation. There are multiple quality control mechanisms to ensure that nascent polypeptides are properly folded and mature proteins maintain their functional conformation. When proteins do misfold, either in the face of normal or pathological stimuli or because of intrinsic mutations or post-translational modifications, they must either be refolded correctly or recycled. In the absence of these corrective processes, they may become toxic to the cell. Herein, we explore some of the underlying mechanisms that lead to proteotoxicity. The continued presence and chronic accumulation of misfolded or unfolded proteins can be disastrous in cardiomyocytes because these misfolded proteins can lead to aggregation or the formation of soluble peptides that are proteotoxic. This in turn leads to compromised protein quality control and precipitating a downward spiral of the cell's ability to maintain protein homeostasis. Some underlying mechanisms are discussed and the therapeutic potential of interfering with proteotoxicity in the heart is explored.
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Affiliation(s)
- Patrick M McLendon
- From the Department of Pediatrics, Children's Hospital Research Foundation, Cincinnati, OH
| | - Jeffrey Robbins
- From the Department of Pediatrics, Children's Hospital Research Foundation, Cincinnati, OH.
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25
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Muñoz R, Aguilar Sandoval F, Wilson CAM, Melo F. Pulling on super paramagnetic beads with micro cantilevers: single molecule mechanical assay application. Phys Biol 2015. [PMID: 26200136 DOI: 10.1088/1478-3975/12/4/046011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
This paper demonstrates that it is possible to trap and release a super paramagnetic micro bead by fixing three super paramagnetic micro beads in a triangular array at the sensitive end of a micro cantilever, and by simply switching on/off an external magnetic field. To provide evidence of this principle we trap a micro bead that is attached to the free end of single DNA molecule and that has been previously fixed at the other end to a glass surface, using the standard sample preparation protocol of magnetic tweezers assays. The switching process is reversible which preserves the integrity of the tethered molecule, and a local force applied over the tethered bead excludes the neighbouring beads from the magnetic trap. We have developed a quadrature phase interferometer which is able to perform under fluid environments to accurately measure small deflections, which permits the exploration of DNA elasticity. Our results agree with measurements from magnetic tweezer assays performed under similar conditions. Furthermore, compared to the magnetic tweezer methodology, the combination of the magnetic trap with a suitable measurement system for cantilever deflection, allows for the exploration of a wide range of forces using a local method that has an improved temporal resolution.
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Affiliation(s)
- Romina Muñoz
- Departamento de Física, Facultad de Ciencia, Universidad de Santiago de Chile, Av. Ecuador 3493, Estación Central, Santiago, Chile
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26
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Affiliation(s)
- Joseph D Puglisi
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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