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Thomas GM, Wu Y, Leite W, Pingali SV, Weiss KL, Grant AJ, Diggs MW, Schmidt-Krey I, Gutishvili G, Gumbart JC, Urban VS, Lieberman RL. SANS reveals lipid-dependent oligomerization of an intramembrane aspartyl protease from H. volcanii. Biophys J 2024; 123:1846-1856. [PMID: 38824390 PMCID: PMC11267423 DOI: 10.1016/j.bpj.2024.05.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 05/05/2024] [Accepted: 05/29/2024] [Indexed: 06/03/2024] Open
Abstract
Reactions that occur within the lipid membrane involve, at minimum, ternary complexes among the enzyme, substrate, and lipid. For many systems, the impact of the lipid in regulating activity or oligomerization state is poorly understood. Here, we used small-angle neutron scattering (SANS) to structurally characterize an intramembrane aspartyl protease (IAP), a class of membrane-bound enzymes that use membrane-embedded aspartate residues to hydrolyze transmembrane segments of biologically relevant substrates. We focused on an IAP ortholog from the halophilic archaeon Haloferax volcanii (HvoIAP). HvoIAP purified in n-dodecyl-β-D-maltoside (DDM) fractionates on size-exclusion chromatography (SEC) as two fractions. We show that, in DDM, the smaller SEC fraction is consistent with a compact HvoIAP monomer. Molecular dynamics flexible fitting conducted on an AlphaFold2-generated monomer produces a model in which loops are compact alongside the membrane-embedded helices. In contrast, SANS data collected on the second SEC fraction indicate an oligomer consistent with an elongated assembly of discrete HvoIAP monomers. Analysis of in-line SEC-SANS data of the HvoIAP oligomer, the first such experiment to be conducted on a membrane protein at Oak Ridge National Lab (ORNL), shows a diversity of elongated and spherical species, including one consistent with the tetrameric assembly reported for the Methanoculleus marisnigri JR1 IAP crystal structure not observed previously in solution. Reconstitution of monomeric HvoIAP into bicelles increases enzyme activity and results in the assembly of HvoIAP into a species with similar dimensions as the ensemble of oligomers isolated from DDM. Our study reveals lipid-mediated HvoIAP self-assembly and demonstrates the utility of in-line SEC-SANS in elucidating oligomerization states of small membrane proteins.
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Affiliation(s)
- Gwendell M Thomas
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia
| | - Yuqi Wu
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia
| | - Wellington Leite
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | | | - Kevin L Weiss
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Arshay J Grant
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Monneh W Diggs
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Ingeborg Schmidt-Krey
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia; School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | | | - James C Gumbart
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia; School of Physics, Georgia Institute of Technology, Atlanta, Georgia
| | - Volker S Urban
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia.
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2
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Wu Y, Thomas GM, Thomsen M, Bahri S, Lieberman RL. Lipid environment modulates processivity and kinetics of a presenilin homolog acting on multiple substrates in vitro. J Biol Chem 2023; 299:105401. [PMID: 38270390 PMCID: PMC10679502 DOI: 10.1016/j.jbc.2023.105401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 09/12/2023] [Accepted: 10/11/2023] [Indexed: 01/26/2024] Open
Abstract
Intramembrane proteases (IPs) hydrolyze peptides in the lipid membrane. IPs participate in a number of cellular pathways including immune response and surveillance, and cholesterol biosynthesis, and they are exploited by viruses for replication. Despite their broad importance across biology, how activity is regulated in the cell to control protein maturation and release of specific bioactive peptides at the right place and right time remains largely unanswered, particularly for the intramembrane aspartyl protease (IAP) subtype. At a molecular biochemical level, different IAP homologs can cleave non-biological substrates, and there is no sequence recognition motif among the nearly 150 substrates identified for just one IAP, presenilin-1, the catalytic component of γ-secretase known for its involvement in the production of amyloid-β plaques associated with Alzheimer disease. Here we used gel-based assays combined with quantitative mass spectrometry and FRET-based kinetics assays to probe the cleavage profile of the presenilin homolog from the methanogen Methanoculleus marisnigri JR1 as a function of the surrounding lipid-mimicking environment, either detergent micelles or bicelles. We selected four biological IAP substrates that have not undergone extensive cleavage profiling previously, namely, the viral core protein of Hepatitis C virus, the viral core protein of Classical Swine Fever virus, the transmembrane segment of Notch-1, and the tyrosine receptor kinase ErbB4. Our study demonstrates a proclivity toward cleavage of substrates at positions of low average hydrophobicity and a consistent role for the lipid environment in modulating kinetic properties.
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Affiliation(s)
- Yuqi Wu
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Gwendell M Thomas
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Max Thomsen
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Sara Bahri
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA.
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3
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Leite WC, Wu Y, Pingali SV, Lieberman RL, Urban VS. Change in Morphology of Dimyristoylphosphatidylcholine/Bile Salt Derivative Bicelle Assemblies with Dodecylmaltoside in the Disk and Ribbon Phases. J Phys Chem Lett 2022; 13:9834-9840. [PMID: 36250687 DOI: 10.1021/acs.jpclett.2c02445] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Bicelles, composed of a mixture of long and short chain lipids, form nanostructured molecular assemblies that are attractive lipid-membrane mimics for in vitro studies of integral membrane proteins. Here we study the effect of a third component, the single chain detergent n-dodecyl-β-d-maltoside (DDM) on the morphology of bicelles composed of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO) below (10 °C) and above (38 °C) the phase transition. In the absence of DDM, bicelles convert from ellipsoidal disks at 10 °C to extended ribbon-like structures at 38 °C. The addition of DDM reshapes the ellipsoidal disc to a circular one and the flattened ribbon to a circular-cylinder worm-like micelle. Knowledge of the influence of the single chain detergent DDM on bicelle nanoscale morphology contributes toward comprehending lipid membrane self-organization and to the goal of optimizing lipid mimics for membrane biology research.
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Affiliation(s)
- Wellington C Leite
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Yuqi Wu
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Sai Venkatesh Pingali
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Volker S Urban
- Neutron Scattering Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
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4
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Feilen LP, Chen SY, Fukumori A, Feederle R, Zacharias M, Steiner H. Active site geometry stabilization of a presenilin homolog by the lipid bilayer promotes intramembrane proteolysis. eLife 2022; 11:76090. [PMID: 35579427 PMCID: PMC9282858 DOI: 10.7554/elife.76090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Cleavage of membrane proteins in the lipid bilayer by intramembrane proteases is crucial for health and disease. Although different lipid environments can potently modulate their activity, how this is linked to their structural dynamics is unclear. Here, we show that the carboxy-peptidase-like activity of the archaeal intramembrane protease PSH, a homolog of the Alzheimer’s disease-associated presenilin/γ-secretase is impaired in micelles and promoted in a lipid bilayer. Comparative molecular dynamics simulations revealed that important elements for substrate binding such as transmembrane domain 6a of PSH are more labile in micelles and stabilized in the lipid bilayer. Moreover, consistent with an enhanced interaction of PSH with a transition-state analog inhibitor, the bilayer promoted the formation of the enzyme’s catalytic active site geometry. Our data indicate that the lipid environment of an intramembrane protease plays a critical role in structural stabilization and active site arrangement of the enzyme-substrate complex thereby promoting intramembrane proteolysis. Cutting proteins into pieces is a crucial process in the cell, allowing several important processes to take place, including cell differentiation (which allows cells to develop into specific types), cell death, protein quality control, or even where in the cell a protein will end up. However, the specialized proteins that carry out this task, known as proteases, can also be involved in the development of disease. For example, in the brain, a protease called γ-secretase cuts up the amyloid-β protein precursor, producing toxic forms of amyloid-β peptides that are widely believed to cause Alzheimer’s disease. Proteases like γ-secretase carry out their role in the membrane, the layer of fats (also known as lipids) that forms the outer boundary of the cell. The environment in this area of the cell can influence the activity of proteases, but it is poorly understood how this happens. One way to address this question would be to compare the activity of γ-secretase in the lipid environment of the membrane to its activity when it is entirely surrounded by different molecules, such as detergent molecules. Unfortunately, γ-secretase is not active when it is removed from its lipid environment by a detergent, making it difficult to perform this comparison. To overcome this issue, Feilen et al. chose to study PSH, a protease similar to γ-secretase that produces the same amyloid-β peptides but remains active in detergent. When Feilen et al. mixed PSH with lipid molecules like those found in the membrane and amyloid-β precursor protein, PSH produced amyloid-β peptides including those that are thought to cause Alzheimer’s. However, when a detergent was substituted for the lipid molecules this led to longer amyloid-β peptides than usual, indicating that PSH was not able to cut proteins as effectively. The change in environment appeared to reduce PSH’s ability to progressively trim small segments from the peptides. Computer modelling of the protease’s structure in lipids versus detergent supported the experimental findings: the model predicted that the areas of PSH important for recognizing and cutting other proteins would be more stable in the membrane compared to the detergent. These results indicate that the cell membrane plays a vital role in the stability of the active regions of proteases that are cleaving in this environment. In the future, this could help to better understand how changes to the lipid molecules in the membrane may contribute to the activity of γ-secretase and its role in Alzheimer’s disease.
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Affiliation(s)
- Lukas P Feilen
- German Center for Neurodegenerative Diseases, Munich, Germany
| | - Shu-Yu Chen
- Physics Department T38, Technical University of Munich, Garching, Germany
| | - Akio Fukumori
- Department of Pharmacotherapeutics II, Osaka Medical and Pharmaceutical University, Takatsuki, Japan
| | - Regina Feederle
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Munich, Germany
| | - Martin Zacharias
- Physics Department T38, Technical University of Munich, Garching, Germany
| | - Harald Steiner
- Biomedical Center (BMC), Ludwig-Maximilians-Universität München, Munich, Germany
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5
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Preparation of a Deuterated Membrane Protein for Small-Angle Neutron Scattering. Methods Mol Biol 2021. [PMID: 33877630 DOI: 10.1007/978-1-0716-1394-8_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
This chapter outlines a protocol developed to prepare a purified deuterated membrane protein for a small-angle neutron scattering (SANS) experiment. SANS is a noninvasive technique well suited to studying membrane protein solution structures, and deuteration enhances the signal from the protein over the background (Breyton et al., Eur Phys J E Soft Matter 36 (7):71, 2013; Garg et al., Biophys J 101 (2):370-377, 2011). We present our workflow: transformation of our plasmid into E. coli, cell growth and expression of our deuterated protein, membrane isolation, detergent solubilization, protein purification, purity assessment, and final preparation for SANS.
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6
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Marki A, Buscher K, Lorenzini C, Meyer M, Saigusa R, Fan Z, Yeh YT, Hartmann N, Dan JM, Kiosses WB, Golden GJ, Ganesan R, Winkels H, Orecchioni M, McArdle S, Mikulski Z, Altman Y, Bui J, Kronenberg M, Chien S, Esko JD, Nizet V, Smalley D, Roth J, Ley K. Elongated neutrophil-derived structures are blood-borne microparticles formed by rolling neutrophils during sepsis. J Exp Med 2021; 218:e20200551. [PMID: 33275138 PMCID: PMC7721910 DOI: 10.1084/jem.20200551] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 09/28/2020] [Accepted: 11/06/2020] [Indexed: 12/30/2022] Open
Abstract
Rolling neutrophils form tethers with submicron diameters. Here, we report that these tethers detach, forming elongated neutrophil-derived structures (ENDS) in the vessel lumen. We studied ENDS formation in mice and humans in vitro and in vivo. ENDS do not contain mitochondria, endoplasmic reticulum, or DNA, but are enriched for S100A8, S100A9, and 57 other proteins. Within hours of formation, ENDS round up, and some of them begin to present phosphatidylserine on their surface (detected by annexin-5 binding) and release S100A8-S100A9 complex, a damage-associated molecular pattern protein that is a known biomarker of neutrophilic inflammation. ENDS appear in blood plasma of mice upon induction of septic shock. Compared with healthy donors, ENDS are 10-100-fold elevated in blood plasma of septic patients. Unlike neutrophil-derived extracellular vesicles, most ENDS are negative for the tetraspanins CD9, CD63, and CD81. We conclude that ENDS are a new class of bloodborne submicron particles with a formation mechanism linked to neutrophil rolling on the vessel wall.
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Affiliation(s)
- Alex Marki
- La Jolla Institute for Immunology, La Jolla, CA
| | - Konrad Buscher
- La Jolla Institute for Immunology, La Jolla, CA
- Division of General Internal Medicine, Nephrology, and Rheumatology, Department of Medicine D, University Hospital Muenster, Muenster, Germany
| | - Cristina Lorenzini
- La Jolla Institute for Immunology, La Jolla, CA
- Laboratory of Immunobiology, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | | | | | - Zhichao Fan
- La Jolla Institute for Immunology, La Jolla, CA
- Department of Immunology, University of Connecticut Health Center, Farmington, CT
| | - Yi-Ting Yeh
- Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA
| | | | - Jennifer M. Dan
- La Jolla Institute for Immunology, La Jolla, CA
- Division of Infectious Diseases and Global Public Health, University of California, San Diego, La Jolla, CA
| | | | - Gregory J. Golden
- Department of Cellular and Molecular Medicine and Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA
| | - Rajee Ganesan
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | | | | | | | | | - Yoav Altman
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA
| | - Jack Bui
- Department of Pathology, University of California, San Diego, La Jolla, CA
| | | | - Shu Chien
- Institute for Immunology, University of Muenster, Muenster, Germany
| | - Jeffrey D. Esko
- Department of Cellular and Molecular Medicine and Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA
| | - Victor Nizet
- Department of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA
| | - David Smalley
- Systems Mass Spectrometry Core, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA
| | - Johannes Roth
- Institute for Immunology, University of Muenster, Muenster, Germany
| | - Klaus Ley
- La Jolla Institute for Immunology, La Jolla, CA
- Department of Bioengineering and Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA
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7
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Lysyk L, Brassard R, Arutyunova E, Siebert V, Jiang Z, Takyi E, Morrison M, Young HS, Lemberg MK, O'Donoghue AJ, Lemieux MJ. Insights into the catalytic properties of the mitochondrial rhomboid protease PARL. J Biol Chem 2021; 296:100383. [PMID: 33556373 PMCID: PMC7966987 DOI: 10.1016/j.jbc.2021.100383] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 12/20/2022] Open
Abstract
The rhomboid protease PARL is a critical regulator of mitochondrial homeostasis through its cleavage of substrates such as PINK1, PGAM5, and Smac/Diablo, which have crucial roles in mitochondrial quality control and apoptosis. However, the catalytic properties of PARL, including the effect of lipids on the protease, have never been characterized in vitro. To address this, we isolated human PARL expressed in yeast and used FRET-based kinetic assays to measure proteolytic activity in vitro. We show that PARL activity in detergent is enhanced by cardiolipin, a lipid enriched in the mitochondrial inner membrane. Significantly higher turnover rates were observed for PARL reconstituted in proteoliposomes, with Smac/Diablo being cleaved most rapidly at a rate of 1 min−1. In contrast, PGAM5 is cleaved with the highest efficiency (kcat/KM) compared with PINK1 and Smac/Diablo. In proteoliposomes, a truncated β-cleavage form of PARL, a physiological form known to affect mitochondrial fragmentation, is more active than the full-length enzyme for hydrolysis of PINK1, PGAM5, and Smac/Diablo. Multiplex profiling of 228 peptides reveals that PARL prefers substrates with a bulky side chain such as Phe in P1, which is distinct from the preference for small side chain residues typically found with bacterial rhomboid proteases. This study using recombinant PARL provides fundamental insights into its catalytic activity and substrate preferences that enhance our understanding of its role in mitochondrial function and has implications for specific inhibitor design.
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Affiliation(s)
- Laine Lysyk
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Raelynn Brassard
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Elena Arutyunova
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Verena Siebert
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Zhenze Jiang
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - Emmanuella Takyi
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Melissa Morrison
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Howard S Young
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Anthony J O'Donoghue
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, USA
| | - M Joanne Lemieux
- Department of Biochemistry, Faculty of Medicine and Dentistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.
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8
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Raut P, Glass JB, Lieberman RL. Archaeal roots of intramembrane aspartyl protease siblings signal peptide peptidase and presenilin. Proteins 2020; 89:232-241. [PMID: 32935885 DOI: 10.1002/prot.26009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/27/2020] [Accepted: 09/13/2020] [Indexed: 12/21/2022]
Abstract
Signal peptides help newly synthesized proteins reach the cell membrane or be secreted. As part of a biological process key to immune response and surveillance in humans, and associated with diseases, for example, Alzheimer, remnant signal peptides and other transmembrane segments are proteolyzed by the intramembrane aspartyl protease (IAP) enzyme family. Here, we identified IAP orthologs throughout the tree of life. In addition to eukaryotes, IAPs are encoded in metabolically diverse archaea from a wide range of environments. We found three distinct clades of archaeal IAPs: (a) Euryarchaeota (eg, halophilic Halobacteriales, methanogenic Methanosarcinales and Methanomicrobiales, marine Poseidoniales, acidophilic Thermoplasmatales, hyperthermophilic Archaeoglobus spp.), (b) DPANN, and (c) Bathyarchaeota, Crenarchaeota, and Asgard. IAPs were also present in bacterial genomes from uncultivated members of Candidate Phylum Radiation, perhaps due to horizontal gene transfer from DPANN archaeal lineages. Sequence analysis of the catalytic motif YD…GXGD (where X is any amino acid) in IAPs from archaea and bacteria reveals WD in Lokiarchaeota and many residue types in the X position. Gene neighborhood analysis in halophilic archaea shows IAP genes near corrinoid transporters (btuCDF genes). In marine Euryarchaeota, a putative BtuF-like domain is found in N-terminus of the IAP gene, suggesting a role for these IAPs in metal ion cofactor or other nutrient scavenging. Interestingly, eukaryotic IAP family members appear to have evolved either from Euryarchaeota or from Asgard archaea. Taken together, our phylogenetic and bioinformatics analysis should prompt experiments to probe the biological roles of IAPs in prokaryotic secretomes.
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Affiliation(s)
- Priyam Raut
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Jennifer B Glass
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA.,School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Raquel L Lieberman
- School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, USA
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9
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Liu X, Zhao J, Zhang Y, Ubarretxena-Belandia I, Forth S, Lieberman RL, Wang C. Substrate-Enzyme Interactions in Intramembrane Proteolysis: γ-Secretase as the Prototype. Front Mol Neurosci 2020; 13:65. [PMID: 32508589 PMCID: PMC7248309 DOI: 10.3389/fnmol.2020.00065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/03/2020] [Indexed: 11/15/2022] Open
Abstract
Intramembrane-cleaving proteases (I-CLiPs) catalyze the hydrolysis of peptide bonds within the transmembrane regions of membrane protein substrates, releasing bioactive fragments that play roles in many physiological and pathological processes. Based on their catalytic mechanism and nucleophile, I-CLiPs are classified into metallo, serine, aspartyl, and glutamyl proteases. Presenilin is the most prominent among I-CLiPs, as the catalytic subunit of γ-secretase (GS) complex responsible for cleaving the amyloid precursor protein (APP) and Notch, as well as many other membrane substrates. Recent cryo-electron microscopy (cryo-EM) structures of GS provide new details on how presenilin recognizes and cleaves APP and Notch. First, presenilin transmembrane helix (TM) 2 and 6 are dynamic. Second, upon binding to GS, the substrate TM helix is unwound from the C-terminus, resulting in an intermolecular β-sheet between the substrate and presenilin. The transition of the substrate C-terminus from α-helix to β-sheet is proposed to expose the scissile peptide bond in an extended conformation, leaving it susceptible to protease cleavage. Despite the astounding new insights in recent years, many crucial questions remain unanswered regarding the inner workings of γ-secretase, however. Key unanswered questions include how the enzyme recognizes and recruits substrates, how substrates are translocated from an initial docking site to the active site, how active site aspartates recruit and coordinate catalytic water, and the nature of the mechanisms of processive trimming of the substrate and product release. Answering these questions will have important implications for drug discovery aimed at selectively reducing the amyloid load in Alzheimer's disease (AD) with minimal side effects.
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Affiliation(s)
- Xinyue Liu
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Jing Zhao
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Yingkai Zhang
- Department of Chemistry, New York University, New York, NY, United States
| | - Iban Ubarretxena-Belandia
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, Leioa, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Scott Forth
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Raquel L. Lieberman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, United States
| | - Chunyu Wang
- Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, United States
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, United States
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY, United States
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10
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The Metastable XBP1u Transmembrane Domain Defines Determinants for Intramembrane Proteolysis by Signal Peptide Peptidase. Cell Rep 2020; 26:3087-3099.e11. [PMID: 30865896 DOI: 10.1016/j.celrep.2019.02.057] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 12/07/2018] [Accepted: 02/14/2019] [Indexed: 11/23/2022] Open
Abstract
Unspliced XBP1 mRNA encodes XBP1u, the transcriptionally inert variant of the unfolded protein response (UPR) transcription factor XBP1s. XBP1u targets its mRNA-ribosome-nascent-chain-complex to the endoplasmic reticulum (ER) to facilitate UPR activation and prevents overactivation. Yet, its membrane association is controversial. Here, we use cell-free translocation and cellular assays to define a moderately hydrophobic stretch in XBP1u that is sufficient to mediate insertion into the ER membrane. Mutagenesis of this transmembrane (TM) region reveals residues that facilitate XBP1u turnover by an ER-associated degradation route that is dependent on signal peptide peptidase (SPP). Furthermore, the impact of these mutations on TM helix dynamics was assessed by residue-specific amide exchange kinetics, evaluated by a semi-automated algorithm. Based on our results, we suggest that SPP-catalyzed intramembrane proteolysis of TM helices is not only determined by their conformational flexibility, but also by side-chain interactions near the scissile peptide bond with the enzyme's active site.
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11
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Barniol-Xicota M, Verhelst SHL. Isolation of intramembrane proteases in membrane-like environments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183193. [PMID: 31945321 DOI: 10.1016/j.bbamem.2020.183193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/07/2020] [Accepted: 01/10/2020] [Indexed: 12/24/2022]
Abstract
Intramembrane proteases (IMPs) are proteolytic enzymes embedded in the lipid bilayer, where they cleave transmembrane substrates. The importance of IMPs relies on their role in a wide variety of cellular processes and diseases. In order to study the activity and function of IMPs, their purified form is often desired. The production of pure and active IMPs has proven to be a challenging task. This process unavoidably requires the use of solubilizing agents that will, to some extent, alter the native environment of these proteases. In this review we present the current solubilization and reconstitution techniques that have been applied to IMPs. In addition, we describe how these techniques had an influence on the activity and structural studies of IMPs, focusing on rhomboid proteases and γ-secretase.
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Affiliation(s)
- Marta Barniol-Xicota
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49, Box 802, B-3000, Belgium.
| | - Steven H L Verhelst
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Chemical Biology, Herestraat 49, Box 802, B-3000, Belgium; Leibniz Institute for Analytical Sciences, ISAS, e.V., Otto-Hahn-Str. 6b, 44227 Dortmund, Germany.
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Lemieux MJ. Taking a position on intramembrane proteolysis. J Biol Chem 2018; 293:4664-4665. [PMID: 29602877 DOI: 10.1074/jbc.h118.002210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Decades of work have contributed to our in-depth mechanistic understanding of soluble proteases, but much less is known about the catalytic mechanism of intramembrane proteolysis due to inherent difficulties in both preparing and analyzing integral membrane enzymes and transmembrane substrates. New work from Naing et al. tackles this challenge by examining the catalytic parameters of an aspartyl intramembrane protease homologous to the enzyme that cleaves amyloid precursor protein, finding that both chemistry and register contribute to specificity in substrate cleavage.
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Affiliation(s)
- M Joanne Lemieux
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2P5, Canada.
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