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Fromm B, Sorger T. Rapid adaptation of cellular metabolic rate to the MicroRNA complements of mammals and its relevance to the evolution of endothermy. iScience 2024; 27:108740. [PMID: 38327773 PMCID: PMC10847693 DOI: 10.1016/j.isci.2023.108740] [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: 11/28/2022] [Revised: 09/13/2023] [Accepted: 12/12/2023] [Indexed: 02/09/2024] Open
Abstract
The metabolic efficiency of mammalian cells depends on the attenuation of intrinsic translation noise by microRNAs. We devised a metric of cellular metabolic rate (cMR), rMR/Mexp optimally fit to the number of microRNA families (mirFam), that is robust to variation in mass and sensitive to body temperature (Tb), consistent with the heat dissipation limit theory of Speakman and Król (2010). Using mirFam as predictor, an Ornstein-Uhlenbeck process of stabilizing selection, with an adaptive shift at the divergence of Boreoeutheria, accounted for 95% of the variation in cMR across mammals. Branchwise rates of evolution of cMR, mirFam and Tb concurrently increased 6- to 7-fold at the divergence of Boreoeutheria, independent of mass. Cellular MR variation across placental mammals was also predicted by the sum of model conserved microRNA-target interactions, revealing an unexpected degree of integration of the microRNA-target apparatus into the energy economy of the mammalian cell.
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Affiliation(s)
- Bastian Fromm
- The Arctic University Museum of Norway, UiT- The Arctic University of Norway, Tromsø, Norway
| | - Thomas Sorger
- Department of Biology, Roger Williams University, Bristol, RI 02809, USA
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2
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Türker F, Brennan A, Margolis SS. Neuronal membrane proteasome-derived peptides modulate NMDAR-dependent neuronal signaling to promote changes in gene expression. Mol Biol Cell 2024; 35:ar6. [PMID: 37910253 PMCID: PMC10881162 DOI: 10.1091/mbc.e23-06-0218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 10/20/2023] [Accepted: 10/20/2023] [Indexed: 11/03/2023] Open
Abstract
The neuronal membrane proteasome (NMP) degrades intracellular proteins into peptides that are released directly into the extracellular space, whereby they stimulate neurons to promote signaling mechanisms that remain unknown. Here, we demonstrate that neuronal stimulation promotes NMP activity and, subsequently, enhanced production of NMP peptides. We show that these neuronal activity-dependent NMP peptides can rapidly promote N-methyl-D-aspartate receptor (NMDAR)-dependent calcium influx in neurons. This leads to sustained phosphorylation of the well-defined stimulus-induced transcription factor, cyclic AMP response element (CRE)-binding protein (CREB). Downstream of these events, we identified changes to neuronal target genes which included increased expression of immediate early genes (e.g., Fos, Npas4, Egr4) and other genes known to have critical neuroregulatory roles. Further observations led to the discovery that NMP peptide-induced changes in gene expression is dependent on NMDARs and independent of AMPA receptors or voltage-gated sodium channels. These data demonstrate that NMP peptides are endogenous and selective activators of NMDA receptors and act as sufficient and novel stimuli within the context of neuronal activity-dependent signaling. This novel pathway is parallel to classic neuronal activity-dependent programs and points to NMP and its resulting peptides as potential modulators of neuronal function.
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Affiliation(s)
- Fulya Türker
- Department of Biological Chemistry, The Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Anna Brennan
- Department of Biological Chemistry, The Johns Hopkins University, School of Medicine, Baltimore, MD 21205
| | - Seth S. Margolis
- Department of Biological Chemistry, The Johns Hopkins University, School of Medicine, Baltimore, MD 21205
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
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3
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Türker F, Bharadwaj RA, Kleinman JE, Weinberger DR, Hyde TM, White CJ, Williams DW, Margolis SS. Orthogonal approaches required to measure proteasome composition and activity in mammalian brain tissue. J Biol Chem 2023:104811. [PMID: 37172721 DOI: 10.1016/j.jbc.2023.104811] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/20/2023] [Accepted: 05/02/2023] [Indexed: 05/15/2023] Open
Abstract
Proteasomes are large macromolecular complexes with multiple distinct catalytic activities that are each vital to human brain health and disease. Despite their importance, standardized approaches to investigate proteasomes have not been universally adapted. Here, we describe pitfalls and define straightforward orthogonal biochemical approaches essential to measure and understand changes in proteasome composition and activity in the mammalian central nervous system. Through our experimentation in the mammalian brain, we determined an abundance of catalytically active proteasomes exist with and without a 19S cap(s), the regulatory particle essential for ubiquitin-dependent degradation. Moreover, we learned that in-cell measurements using activity-based probes (ABPs) are more sensitive in determining the available activity of the 20S proteasome without the 19S cap and in measuring individual catalytic subunit activities of each β subunit within all neuronal proteasomes. Subsequently, applying these tools to human brain samples, we were surprised to find that post-mortem tissue retained little to no 19S-capped proteasome, regardless of age, sex, or disease state. Comparing brain tissues (parahippocampal gyrus) from human Alzheimer's disease (AD) patients and unaffected subjects, available 20S proteasome activity was significantly elevated in severe cases of AD, an observation not previously noted. Taken together, our study establishes standardized approaches for comprehensive investigation of proteasomes in mammalian brain tissue, and we reveal new insight into brain proteasome biology.
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Affiliation(s)
- Fulya Türker
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Rahul A Bharadwaj
- The Lieber Institute for Brain Development, Baltimore, MD 21205, USA
| | - Joel E Kleinman
- The Lieber Institute for Brain Development, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel R Weinberger
- The Lieber Institute for Brain Development, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thomas M Hyde
- The Lieber Institute for Brain Development, Baltimore, MD 21205, USA; Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Cory J White
- Department of Molecular and Comparative Pathobiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Dionna W Williams
- Department of Molecular and Comparative Pathobiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Medicine, Division of Clinical Pharmacology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA; Department of Molecular Microbiology & Immunology, Johns Hopkins School of Public Health, Baltimore, Maryland 21205, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seth S Margolis
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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4
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Krüger G, Kirkpatrick J, Mahieu E, Franzetti B, Gabel F, Carlomagno T. A real-time analysis of GFP unfolding by the AAA+ unfoldase PAN. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2023; 350:107431. [PMID: 37058954 DOI: 10.1016/j.jmr.2023.107431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/27/2023] [Accepted: 03/30/2023] [Indexed: 05/10/2023]
Abstract
Protein quality control systems are essential to maintain a healthy proteome. They often consist of an unfoldase unit, typically an AAA+ ATPase, coupled with a protease unit. In all kingdoms of life, they function to eliminate misfolded proteins, and thus prevent that their aggregates do harm to the cell, and to rapidly regulate protein levels in the presence of environmental changes. Despite the huge progress made in the past two decades in understanding the mechanism of function of protein degradation systems, the fate of the substrate during the unfolding and proteolytic processes remains poorly understood. Here we exploit an NMR-based approach to monitor GFP processing by the archaeal PAN unfoldase and the PAN-20S degradation system in real time. We find that PAN-dependent unfolding of GFP does not involve the release of partially-folded GFP molecules resulting from futile unfolding attempts. In contrast, once stably engaged with PAN, GFP molecules are efficiently transferred to the proteolytic chamber of the 20S subunit, despite the only weak affinity of PAN for the 20S subunit in the absence of substrate. This is essential to guarantee that unfolded but not proteolyzed proteins are not released into solution, where they would form toxic aggregates. The results of our studies are in good agreement with previous results derived from real-time small-angle-neutron-scattering experiments and have the advantage of allowing the investigation of substrates and products at amino-acid resolution.
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Affiliation(s)
- Georg Krüger
- Institute of Organic Chemistry and Centre of Biomolecular Drug Design, Leibniz University Hannover, Schneiderberg 38, D-30167 Hannover, Germany
| | - John Kirkpatrick
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, B15 2TT Birmingham, United Kingdom
| | - Emilie Mahieu
- Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Bruno Franzetti
- Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Frank Gabel
- Univ. Grenoble Alpes, CEA, CNRS, IBS, 71 avenue des Martyrs, F-38000 Grenoble, France
| | - Teresa Carlomagno
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, B15 2TT Birmingham, United Kingdom.
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5
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The proteasome and its role in the nervous system. Cell Chem Biol 2021; 28:903-917. [PMID: 33905676 DOI: 10.1016/j.chembiol.2021.04.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/04/2021] [Accepted: 04/05/2021] [Indexed: 12/14/2022]
Abstract
Proteasomes are multisubunit complexes that catalyze the majority of protein degradation in mammalian cells to maintain protein homeostasis and influence the regulation of most cellular processes. The proteasome, a multicatalytic protease complex, is a ring-like structure with a narrow pore that exhibits regulated gating, enabling the selective degradation of target proteins into peptide fragments. This process of removing proteins is essential for eliminating proteins that are no longer wanted, such as unfolded or aggregated proteins. This is important for preserving cellular function relevant to brain health and disease. Recently, in the nervous system, specialized proteasomes have been shown to generate peptides with important cellular functions. These discoveries challenge the prevailing notion that proteasomes primarily operate to eliminate proteins and identify signaling-competent proteasomes. This review focuses on the structure, function, and regulation of proteasomes and sheds light on emerging areas of investigation regarding the role of proteasomes in the nervous system.
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6
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Abstract
Multiple gram-negative bacteria encode type III secretion systems (T3SS) that allow them to inject effector proteins directly into host cells to facilitate colonization. To be secreted, effector proteins must be at least partially unfolded to pass through the narrow needle-like channel (diameter <2 nm) of the T3SS. Fusion of effector proteins to tightly packed proteins-such as GFP, ubiquitin, or dihydrofolate reductase (DHFR)-impairs secretion and results in obstruction of the T3SS. Prior observation that unfolding can become rate-limiting for secretion has led to the model that T3SS effector proteins have low thermodynamic stability, facilitating their secretion. Here, we first show that the unfolding free energy ([Formula: see text]) of two Salmonella effector proteins, SptP and SopE2, are 6.9 and 6.0 kcal/mol, respectively, typical for globular proteins and similar to published [Formula: see text] for GFP, ubiquitin, and DHFR. Next, we mechanically unfolded individual SptP and SopE2 molecules by atomic force microscopy (AFM)-based force spectroscopy. SptP and SopE2 unfolded at low force (F unfold ≤ 17 pN at 100 nm/s), making them among the most mechanically labile proteins studied to date by AFM. Moreover, their mechanical compliance is large, as measured by the distance to the transition state (Δx ‡ = 1.6 and 1.5 nm for SptP and SopE2, respectively). In contrast, prior measurements of GFP, ubiquitin, and DHFR show them to be mechanically robust (F unfold > 80 pN) and brittle (Δx ‡ < 0.4 nm). These results suggest that effector protein unfolding by T3SS is a mechanical process and that mechanical lability facilitates efficient effector protein secretion.
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7
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Chhun A, Sousoni D, Aguiló‐Ferretjans MDM, Song L, Corre C, Christie‐Oleza JA. Phytoplankton trigger the production of cryptic metabolites in the marine actinobacterium Salinispora tropica. Microb Biotechnol 2021; 14:291-306. [PMID: 33280260 PMCID: PMC7888443 DOI: 10.1111/1751-7915.13722] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/14/2020] [Indexed: 12/19/2022] Open
Abstract
Filamentous members of the phylum Actinobacteria are a remarkable source of natural products with pharmaceutical potential. The discovery of novel molecules from these organisms is, however, hindered because most of the biosynthetic gene clusters (BGCs) encoding these secondary metabolites are cryptic or silent and are referred to as orphan BGCs. While co-culture has proven to be a promising approach to unlock the biosynthetic potential of many microorganisms by activating the expression of these orphan BGCs, it still remains an underexplored technique. The marine actinobacterium Salinispora tropica, for instance, produces valuable compounds such as the anti-cancer molecule salinosporamide but half of its putative BGCs are still orphan. Although previous studies have used marine heterotrophs to induce orphan BGCs in Salinispora, its co-culture with marine phototrophs has yet to be investigated. Following the observation of an antimicrobial activity against a range of phytoplankton by S. tropica, we here report that the photosynthate released by photosynthetic primary producers influences its biosynthetic capacities with production of cryptic molecules and the activation of orphan BGCs. Our work, using an approach combining metabolomics and proteomics, pioneers the use of phototrophs as a promising strategy to accelerate the discovery of novel natural products from marine actinobacteria.
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Affiliation(s)
- Audam Chhun
- School of Life SciencesUniversity of WarwickCoventryUK
| | | | | | - Lijiang Song
- Department of ChemistryUniversity of WarwickCoventryUK
| | - Christophe Corre
- School of Life SciencesUniversity of WarwickCoventryUK
- Department of ChemistryUniversity of WarwickCoventryUK
| | - Joseph A. Christie‐Oleza
- School of Life SciencesUniversity of WarwickCoventryUK
- University of the Balearic IslandsPalmaSpain
- IMEDEA (CSIC‐UIB)EsporlesSpain
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8
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The ubiquitin-proteasome system and its crosstalk with mitochondria as therapeutic targets in medicine. Pharmacol Res 2020; 163:105248. [PMID: 33065283 DOI: 10.1016/j.phrs.2020.105248] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022]
Abstract
The ubiquitin-proteasome system constitutes a major pathway for protein degradation in the cell. Therefore the crosstalk of this pathway with mitochondria is a major topic with direct relevance to many mitochondrial diseases. Proteasome dysfunction triggers not only protein toxicity, but also mitochondrial dysfunction. The involvement of proteasomes in the regulation of protein transport into mitochondria contributes to an increase in mitochondrial function defects. On the other hand, mitochondrial impairment stimulates reactive oxygen species production, which increases protein damage, and protein misfolding and aggregation leading to proteasome overload. Concurrently, mitochondrial dysfunction compromises cellular ATP production leading to reduced protein ubiquitination and proteasome activity. In this review we discuss the complex relationship and interdependence of the ubiquitin-proteasome system and mitochondria. Furthermore, we describe pharmacological inhibition of proteasome activity as a novel strategy to treat a group of mitochondrial diseases.
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9
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Bragança CE, Kraut DA. Mode of targeting to the proteasome determines GFP fate. J Biol Chem 2020; 295:15892-15901. [PMID: 32913119 DOI: 10.1074/jbc.ra120.015235] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/04/2020] [Indexed: 12/22/2022] Open
Abstract
The ubiquitin-proteasome system is the canonical pathway for protein degradation in eukaryotic cells. GFP is frequently used as a reporter in proteasomal degradation assays. However, there are multiple variants of GFP in use, and these variants have different intrinsic stabilities. Further, there are multiple means by which substrates are targeted to the proteasome, and these differences could also affect the proteasome's ability to unfold and degrade substrates. Herein we investigate how the fate of GFP variants of differing intrinsic stabilities is determined by the mode of targeting to the proteasome. We compared two targeting systems: linear Ub4 degrons and the UBL domain from yeast Rad23, both of which are commonly used in degradation experiments. Surprisingly, the UBL degron allows for degradation of the most stable sGFP-containing substrates, whereas the Ub4 degron does not. Destabilizing the GFP by circular permutation allows degradation with either targeting signal, indicating that domain stability and mode of targeting combine to determine substrate fate. Difficult-to-unfold substrates are released and re-engaged multiple times, with removal of the degradation initiation region providing an alternative clipping pathway that precludes unfolding and degradation; the UBL degron favors degradation of even difficult-to-unfold substrates, whereas the Ub4 degron favors clipping. Finally, we show that the ubiquitin receptor Rpn13 is primarily responsible for the enhanced ability of the proteasome to degrade stable UBL-tagged substrates. Our results indicate that the choice of targeting method and reporter protein are critical to the design of protein degradation experiments.
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Affiliation(s)
| | - Daniel Adam Kraut
- Department of Chemistry, Villanova University, Villanova, Pennsylvania, USA.
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10
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Davis PR, Miller SG, Verhoeven NA, Morgan JS, Tulis DA, Witczak CA, Brault JJ. Increased AMP deaminase activity decreases ATP content and slows protein degradation in cultured skeletal muscle. Metabolism 2020; 108:154257. [PMID: 32370945 PMCID: PMC7319876 DOI: 10.1016/j.metabol.2020.154257] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/18/2020] [Accepted: 04/29/2020] [Indexed: 12/15/2022]
Abstract
BACKGROUND Protein degradation is an energy-dependent process, requiring ATP at multiple steps. However, reports conflict as to the relationship between intracellular energetics and the rate of proteasome-mediated protein degradation. METHODS To determine whether the concentration of the adenine nucleotide pool (ATP + ADP + AMP) affects protein degradation in muscle cells, we overexpressed an AMP degrading enzyme, AMP deaminase 3 (AMPD3), via adenovirus in C2C12 myotubes. RESULTS Overexpression of AMPD3 resulted in a dose- and time-dependent reduction of total adenine nucleotides (ATP, ADP and AMP) without increasing the ADP/ATP or AMP/ATP ratios. In agreement, the reduction of total adenine nucleotide concentration did not result in increased Thr172 phosphorylation of AMP-activated protein kinase (AMPK), a common indicator of intracellular energetic state. Furthermore, LC3 protein accumulation and ULK1 (Ser 555) phosphorylation were not induced. However, overall protein degradation and ubiquitin-dependent proteolysis were slowed by overexpression of AMPD3, despite unchanged content of several proteasome subunit proteins and proteasome activity in vitro under standard conditions. CONCLUSIONS Altogether, these findings indicate that a physiologically relevant decrease in ATP content, without a concomitant increase in ADP or AMP, is sufficient to decrease the rate of protein degradation and activity of the ubiquitin-proteasome system in muscle cells. This suggests that adenine nucleotide degrading enzymes, such as AMPD3, may be a viable target to control muscle protein degradation and perhaps muscle mass.
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Affiliation(s)
- Patrick R Davis
- Department of Kinesiology, East Carolina University, United States of America
| | - Spencer G Miller
- Department of Kinesiology, East Carolina University, United States of America
| | - Nicolas A Verhoeven
- Department of Kinesiology, East Carolina University, United States of America
| | - Joshua S Morgan
- Department of Physiology, Brody School of Medicine, East Carolina University, United States of America
| | - David A Tulis
- Department of Physiology, Brody School of Medicine, East Carolina University, United States of America
| | - Carol A Witczak
- Department of Kinesiology, East Carolina University, United States of America; Department of Physiology, Brody School of Medicine, East Carolina University, United States of America; Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, United States of America
| | - Jeffrey J Brault
- Department of Kinesiology, East Carolina University, United States of America; Department of Physiology, Brody School of Medicine, East Carolina University, United States of America; Department of Biochemistry & Molecular Biology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, United States of America.
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11
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Visootsat A, Nakamura A, Vignon P, Watanabe H, Uchihashi T, Iino R. Single-molecule imaging analysis reveals the mechanism of a high-catalytic-activity mutant of chitinase A from Serratia marcescens. J Biol Chem 2020; 295:1915-1925. [PMID: 31924658 PMCID: PMC7029130 DOI: 10.1074/jbc.ra119.012078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/03/2020] [Indexed: 12/17/2022] Open
Abstract
Chitin degradation is important for biomass conversion and has potential applications for agriculture, biotechnology, and the pharmaceutical industry. Chitinase A from the Gram-negative bacterium Serratia marcescens (SmChiA) is a processive enzyme that hydrolyzes crystalline chitin as it moves linearly along the substrate surface. In a previous study, the catalytic activity of SmChiA against crystalline chitin was found to increase after the tryptophan substitution of two phenylalanine residues (F232W and F396W), located at the entrance and exit of the substrate binding cleft of the catalytic domain, respectively. However, the mechanism underlying this high catalytic activity remains elusive. In this study, single-molecule fluorescence imaging and high-speed atomic force microscopy were applied to understand the mechanism of this high-catalytic-activity mutant. A reaction scheme including processive catalysis was used to reproduce the properties of SmChiA WT and F232W/F396W, in which all of the kinetic parameters were experimentally determined. High activity of F232W/F396W mutant was caused by a high processivity and a low dissociation rate constant after productive binding. The turnover numbers for both WT and F232W/F396W, determined by the biochemical analysis, were well-replicated using the kinetic parameters obtained from single-molecule imaging analysis, indicating the validity of the reaction scheme. Furthermore, alignment of amino acid sequences of 258 SmChiA-like proteins revealed that tryptophan, not phenylalanine, is the predominant amino acid at the corresponding positions (Phe-232 and Phe-396 for SmChiA). Our study will be helpful for understanding the kinetic mechanisms and further improvement of crystalline chitin hydrolytic activity of SmChiA mutants.
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Affiliation(s)
- Akasit Visootsat
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan; Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Akihiko Nakamura
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan; Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Paul Vignon
- Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan; Chimie ParisTech, Paris 75231, France
| | - Hiroki Watanabe
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8601, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Science, Okazaki, Aichi 444-8787, Japan
| | - Takayuki Uchihashi
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8601, Japan; Exploratory Research Center on Life and Living Systems (ExCELLS), National Institute of Natural Science, Okazaki, Aichi 444-8787, Japan
| | - Ryota Iino
- Department of Functional Molecular Science, School of Physical Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0193, Japan; Institute for Molecular Science, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan.
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12
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Kors S, Geijtenbeek K, Reits E, Schipper-Krom S. Regulation of Proteasome Activity by (Post-)transcriptional Mechanisms. Front Mol Biosci 2019; 6:48. [PMID: 31380390 PMCID: PMC6646590 DOI: 10.3389/fmolb.2019.00048] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/11/2019] [Indexed: 12/23/2022] Open
Abstract
Intracellular protein synthesis, folding, and degradation are tightly controlled processes to ensure proper protein homeostasis. The proteasome is responsible for the degradation of the majority of intracellular proteins, which are often targeted for degradation via polyubiquitination. However, the degradation rate of proteins is also affected by the capacity of proteasomes to recognize and degrade these substrate proteins. This capacity is regulated by a variety of proteasome modulations including (1) changes in complex composition, (2) post-translational modifications, and (3) altered transcription of proteasomal subunits and activators. Various diseases are linked to proteasome modulation and altered proteasome function. A better understanding of these modulations may offer new perspectives for therapeutic intervention. Here we present an overview of these three proteasome modulating mechanisms to give better insight into the diversity of proteasomes.
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Affiliation(s)
- Suzan Kors
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Karlijne Geijtenbeek
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Eric Reits
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Sabine Schipper-Krom
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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13
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Abstract
The ubiquitin proteasome system (UPS) degrades individual proteins in a highly regulated fashion and is responsible for the degradation of misfolded, damaged, or unneeded cellular proteins. During the past 20 years, investigators have established a critical role for the UPS in essentially every cellular process, including cell cycle progression, transcriptional regulation, genome integrity, apoptosis, immune responses, and neuronal plasticity. At the center of the UPS is the proteasome, a large and complex molecular machine containing a multicatalytic protease complex. When the efficiency of this proteostasis system is perturbed, misfolded and damaged protein aggregates can accumulate to toxic levels and cause neuronal dysfunction, which may underlie many neurodegenerative diseases. In addition, many cancers rely on robust proteasome activity for degrading tumor suppressors and cell cycle checkpoint inhibitors necessary for rapid cell division. Thus, proteasome inhibitors have proven clinically useful to treat some types of cancer, especially multiple myeloma. Numerous cellular processes rely on finely tuned proteasome function, making it a crucial target for future therapeutic intervention in many diseases, including neurodegenerative diseases, cystic fibrosis, atherosclerosis, autoimmune diseases, diabetes, and cancer. In this review, we discuss the structure and function of the proteasome, the mechanisms of action of different proteasome inhibitors, various techniques to evaluate proteasome function in vitro and in vivo, proteasome inhibitors in preclinical and clinical development, and the feasibility for pharmacological activation of the proteasome to potentially treat neurodegenerative disease.
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Affiliation(s)
- Tiffany A Thibaudeau
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia
| | - David M Smith
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia
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14
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Snoberger A, Brettrager EJ, Smith DM. Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing. Nat Commun 2018; 9:2374. [PMID: 29915197 PMCID: PMC6006169 DOI: 10.1038/s41467-018-04731-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 05/18/2018] [Indexed: 12/15/2022] Open
Abstract
Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conformations: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN's symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases' coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils regulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity.
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Affiliation(s)
- Aaron Snoberger
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
| | - Evan J Brettrager
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, 26501, USA
| | - David M Smith
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, WV, 26506, USA.
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15
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The Logic of the 26S Proteasome. Cell 2017; 169:792-806. [PMID: 28525752 DOI: 10.1016/j.cell.2017.04.023] [Citation(s) in RCA: 562] [Impact Index Per Article: 80.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 12/14/2022]
Abstract
The ubiquitin proteasome pathway is responsible for most of the protein degradation in mammalian cells. Rates of degradation by this pathway have generally been assumed to be determined by rates of ubiquitylation. However, recent studies indicate that proteasome function is also tightly regulated and determines whether a ubiquitylated protein is destroyed or deubiquitylated and survives longer. This article reviews recent advances in our understanding of the proteasome's multistep ATP-dependent mechanism, its biochemical and structural features that ensure efficient proteolysis and ubiquitin recycling while preventing nonselective proteolysis, and the regulation of proteasome activity by interacting proteins and subunit modifications, especially phosphorylation.
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