1
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Chamness LM, Kuntz CP, McKee AG, Penn WD, Hemmerich CM, Rusch DB, Woods H, Dyotima, Meiler J, Schlebach JP. Divergent folding-mediated epistasis among unstable membrane protein variants. eLife 2024; 12:RP92406. [PMID: 39078397 PMCID: PMC11288631 DOI: 10.7554/elife.92406] [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: 07/31/2024] Open
Abstract
Many membrane proteins are prone to misfolding, which compromises their functional expression at the plasma membrane. This is particularly true for the mammalian gonadotropin-releasing hormone receptor GPCRs (GnRHR). We recently demonstrated that evolutionary GnRHR modifications appear to have coincided with adaptive changes in cotranslational folding efficiency. Though protein stability is known to shape evolution, it is unclear how cotranslational folding constraints modulate the synergistic, epistatic interactions between mutations. We therefore compared the pairwise interactions formed by mutations that disrupt the membrane topology (V276T) or tertiary structure (W107A) of GnRHR. Using deep mutational scanning, we evaluated how the plasma membrane expression of these variants is modified by hundreds of secondary mutations. An analysis of 251 mutants in three genetic backgrounds reveals that V276T and W107A form distinct epistatic interactions that depend on both the severity and the mechanism of destabilization. V276T forms predominantly negative epistatic interactions with destabilizing mutations in soluble loops. In contrast, W107A forms positive interactions with mutations in both loops and transmembrane domains that reflect the diminishing impacts of the destabilizing mutations in variants that are already unstable. These findings reveal how epistasis is remodeled by conformational defects in membrane proteins and in unstable proteins more generally.
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Affiliation(s)
- Laura M Chamness
- Department of Chemistry, Indiana UniversityBloomingtonUnited States
| | - Charles P Kuntz
- The James Tarpo Jr. and Margaret Tarpo Department of Chemistry, Purdue UniversityWest LafayetteUnited States
| | - Andrew G McKee
- Department of Chemistry, Indiana UniversityBloomingtonUnited States
| | - Wesley D Penn
- Department of Chemistry, Indiana UniversityBloomingtonUnited States
| | | | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana UniversityBloomingtonUnited States
| | - Hope Woods
- Department of Chemistry, Vanderbilt UniversityNashvilleUnited States
- Chemical and Physical Biology Program, Vanderbilt UniversityNashvilleUnited States
| | - Dyotima
- Department of Chemistry, Indiana UniversityBloomingtonUnited States
| | - Jens Meiler
- Department of Chemistry, Vanderbilt UniversityNashvilleUnited States
- Institute for Drug Discovery, Leipzig UniversityLeipzigGermany
| | - Jonathan P Schlebach
- The James Tarpo Jr. and Margaret Tarpo Department of Chemistry, Purdue UniversityWest LafayetteUnited States
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2
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Carmody P, Roushar FJ, Tedman A, Wang W, Herwig M, Kim M, McDonald EF, Noguera K, Wong-Roushar J, Poirier JL, Zelt NB, Pockrass BT, McKee AG, Kuntz CP, Raju SV, Plate L, Penn WD, Schlebach JP. Ribosomal Frameshifting Selectively Modulates the Assembly, Function, and Pharmacological Rescue of a Misfolded CFTR Variant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.02.539166. [PMID: 39091758 PMCID: PMC11290997 DOI: 10.1101/2023.05.02.539166] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
The cotranslational misfolding of the cystic fibrosis transmembrane conductance regulator chloride channel (CFTR) plays a central role in the molecular basis of cystic fibrosis (CF). The misfolding of the most common CF variant (ΔF508) remodels both the translational regulation and quality control of CFTR. Nevertheless, it is unclear how the misassembly of the nascent polypeptide may directly influence the activity of the translation machinery. In this work, we identify a structural motif within the CFTR transcript that stimulates efficient -1 ribosomal frameshifting and triggers the premature termination of translation. Though this motif does not appear to impact the interactome of wild-type CFTR, silent mutations that disrupt this RNA structure alter the association of nascent ΔF508 CFTR with numerous translation and quality control proteins. Moreover, disrupting this RNA structure enhances the functional gating of the ΔF508 CFTR channel at the plasma membrane and its pharmacological rescue by the CFTR modulators contained in the CF drug Trikafta. The effects of the RNA structure on ΔF508 CFTR appear to be attenuated in the absence of the ER membrane protein complex (EMC), which was previously found to modulate ribosome collisions during "preemptive quality control" of a misfolded CFTR homolog. Together, our results reveal that ribosomal frameshifting selectively modulates the assembly, function, and pharmacological rescue of a misfolded CFTR variant. These findings suggest interactions between the nascent chain, quality control machinery, and ribosome may dynamically modulate ribosomal frameshifting in order to tune the processivity of translation in response to cotranslational misfolding.
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Affiliation(s)
- Patrick Carmody
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Francis J. Roushar
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Austin Tedman
- The James Tarpo Jr. and Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN, USA 47907
| | - Wei Wang
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA 35233
| | - Madeline Herwig
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA 37240
| | - Minsoo Kim
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA 37240
- Program in Chemical and Physical Biology, Vanderbilt University, Nashville, TN, USA 37240
| | - Eli F. McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA 37240
| | - Karen Noguera
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | | | - Jon-Luc Poirier
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Nathan B. Zelt
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Ben T. Pockrass
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Andrew G. McKee
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Charles P. Kuntz
- The James Tarpo Jr. and Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN, USA 47907
| | - S. Vamsee Raju
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA 35233
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA 37240
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA 37240
| | - Wesley D. Penn
- Department of Chemistry, Indiana University Bloomington, Bloomington, IN, USA 47401
| | - Jonathan P. Schlebach
- The James Tarpo Jr. and Margaret Tarpo Department of Chemistry, Purdue University, West Lafayette, IN, USA 47907
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3
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Yee SW, Macdonald CB, Mitrovic D, Zhou X, Koleske ML, Yang J, Buitrago Silva D, Rockefeller Grimes P, Trinidad DD, More SS, Kachuri L, Witte JS, Delemotte L, Giacomini KM, Coyote-Maestas W. The full spectrum of SLC22 OCT1 mutations illuminates the bridge between drug transporter biophysics and pharmacogenomics. Mol Cell 2024; 84:1932-1947.e10. [PMID: 38703769 DOI: 10.1016/j.molcel.2024.04.008] [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: 01/04/2024] [Accepted: 04/15/2024] [Indexed: 05/06/2024]
Abstract
Mutations in transporters can impact an individual's response to drugs and cause many diseases. Few variants in transporters have been evaluated for their functional impact. Here, we combine saturation mutagenesis and multi-phenotypic screening to dissect the impact of 11,213 missense single-amino-acid deletions, and synonymous variants across the 554 residues of OCT1, a key liver xenobiotic transporter. By quantifying in parallel expression and substrate uptake, we find that most variants exert their primary effect on protein abundance, a phenotype not commonly measured alongside function. Using our mutagenesis results combined with structure prediction and molecular dynamic simulations, we develop accurate structure-function models of the entire transport cycle, providing biophysical characterization of all known and possible human OCT1 polymorphisms. This work provides a complete functional map of OCT1 variants along with a framework for integrating functional genomics, biophysical modeling, and human genetics to predict variant effects on disease and drug efficacy.
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Affiliation(s)
- Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Christian B Macdonald
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Darko Mitrovic
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, 12121 Solna, Stockholm, Stockholm County 114 28, Sweden
| | - Xujia Zhou
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Megan L Koleske
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Jia Yang
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Dina Buitrago Silva
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Patrick Rockefeller Grimes
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Donovan D Trinidad
- Department of Medicine, Division of Infectious Disease, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Swati S More
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Linda Kachuri
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University, Stanford, CA 94305, USA
| | - John S Witte
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford University, Stanford, CA 94305, USA
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, 12121 Solna, Stockholm, Stockholm County 114 28, Sweden.
| | - Kathleen M Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Willow Coyote-Maestas
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94143, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA 94143, USA; Chan Zuckerberg Biohub, San Francisco, CA 94148, USA.
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4
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Howard MK, Hoppe N, Huang XP, Macdonald CB, Mehrota E, Grimes PR, Zahm A, Trinidad DD, English J, Coyote-Maestas W, Manglik A. Molecular basis of proton-sensing by G protein-coupled receptors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.17.590000. [PMID: 38659943 PMCID: PMC11042331 DOI: 10.1101/2024.04.17.590000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Three proton-sensing G protein-coupled receptors (GPCRs), GPR4, GPR65, and GPR68, respond to changes in extracellular pH to regulate diverse physiology and are implicated in a wide range of diseases. A central challenge in determining how protons activate these receptors is identifying the set of residues that bind protons. Here, we determine structures of each receptor to understand the spatial arrangement of putative proton sensing residues in the active state. With a newly developed deep mutational scanning approach, we determined the functional importance of every residue in proton activation for GPR68 by generating ~9,500 mutants and measuring effects on signaling and surface expression. This unbiased screen revealed that, unlike other proton-sensitive cell surface channels and receptors, no single site is critical for proton recognition in GPR68. Instead, a network of titratable residues extend from the extracellular surface to the transmembrane region and converge on canonical class A GPCR activation motifs to activate proton-sensing GPCRs. More broadly, our approach integrating structure and unbiased functional interrogation defines a new framework for understanding the rich complexity of GPCR signaling.
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Affiliation(s)
- Matthew K. Howard
- Tetrad graduate program, University of California, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, CA, USA
| | - Nicholas Hoppe
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
- Biophysics graduate program, University of California, San Francisco, CA, USA
| | - Xi-Ping Huang
- Department of Pharmacology and the National Institute of Mental Health Psychoactive Drug Screening Program (NIMH PDSP), The University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Christian B. Macdonald
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, CA, USA
| | - Eshan Mehrota
- Tetrad graduate program, University of California, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
- Medical Scientist Training Program, University of California, San Francisco, CA, USA
| | | | - Adam Zahm
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Donovan D. Trinidad
- Department of Medicine, Division of Infectious Disease, University of California, San Francisco, United States
| | - Justin English
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Willow Coyote-Maestas
- Department of Bioengineering and Therapeutic Science, University of California, San Francisco, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Quantitative Biosciences Institute, University of California, San Francisco, USA
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Quantitative Biosciences Institute, University of California, San Francisco, USA
- Department of Anesthesia and Perioperative Care, University of California, San Francisco, CA, USA
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5
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Scott BM, Chen SK, Van Nynatten A, Liu J, Schott RK, Heon E, Peisajovich SG, Chang BSW. Scaling up Functional Analyses of the G Protein-Coupled Receptor Rhodopsin. J Mol Evol 2024; 92:61-71. [PMID: 38324225 DOI: 10.1007/s00239-024-10154-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 12/22/2023] [Indexed: 02/08/2024]
Abstract
Eukaryotic cells use G protein-coupled receptors (GPCRs) to convert external stimuli into internal signals to elicit cellular responses. However, how mutations in GPCR-coding genes affect GPCR activation and downstream signaling pathways remain poorly understood. Approaches such as deep mutational scanning show promise in investigations of GPCRs, but a high-throughput method to measure rhodopsin activation has yet to be achieved. Here, we scale up a fluorescent reporter assay in budding yeast that we engineered to study rhodopsin's light-activated signal transduction. Using this approach, we measured the mutational effects of over 1200 individual human rhodopsin mutants, generated by low-frequency random mutagenesis of the GPCR rhodopsin (RHO) gene. Analysis of the data in the context of rhodopsin's three-dimensional structure reveals that transmembrane helices are generally less tolerant to mutations compared to flanking helices that face the lipid bilayer, which suggest that mutational tolerance is contingent on both the local environment surrounding specific residues and the specific position of these residues in the protein structure. Comparison of functional scores from our screen to clinically identified rhodopsin disease variants found many pathogenic mutants to be loss of function. Lastly, functional scores from our assay were consistent with a complex counterion mechanism involved in ligand-binding and rhodopsin activation. Our results demonstrate that deep mutational scanning is possible for rhodopsin activation and can be an effective method for revealing properties of mutational tolerance that may be generalizable to other transmembrane proteins.
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Affiliation(s)
- Benjamin M Scott
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Steven K Chen
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | | | - Jing Liu
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Ryan K Schott
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
- Department of Biology and Centre for Vision Research, York University, Toronto, ON, Canada
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Elise Heon
- Department of Ophthalmology, Hospital for Sick Children, Toronto, ON, Canada
| | - Sergio G Peisajovich
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Belinda S W Chang
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON, Canada.
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6
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Chamness LM, Kuntz CP, McKee AG, Penn WD, Hemmerich CM, Rusch DB, Woods H, Dyotima, Meiler J, Schlebach JP. Divergent Folding-Mediated Epistasis Among Unstable Membrane Protein Variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.25.554866. [PMID: 37662415 PMCID: PMC10473758 DOI: 10.1101/2023.08.25.554866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Many membrane proteins are prone to misfolding, which compromises their functional expression at the plasma membrane. This is particularly true for the mammalian gonadotropin-releasing hormone receptor GPCRs (GnRHR). We recently demonstrated that evolutionary GnRHR modifications appear to have coincided with adaptive changes in cotranslational folding efficiency. Though protein stability is known to shape evolution, it is unclear how cotranslational folding constraints modulate the synergistic, epistatic interactions between mutations. We therefore compared the pairwise interactions formed by mutations that disrupt the membrane topology (V276T) or tertiary structure (W107A) of GnRHR. Using deep mutational scanning, we evaluated how the plasma membrane expression of these variants is modified by hundreds of secondary mutations. An analysis of 251 mutants in three genetic backgrounds reveals that V276T and W107A form distinct epistatic interactions that depend on both the severity and the mechanism of destabilization. V276T forms predominantly negative epistatic interactions with destabilizing mutations in soluble loops. In contrast, W107A forms positive interactions with mutations in both loops and transmembrane domains that reflect the diminishing impacts of the destabilizing mutations in variants that are already unstable. These findings reveal how epistasis is remodeled by conformational defects in membrane proteins and in unstable proteins more generally.
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Affiliation(s)
- Laura M. Chamness
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Charles P. Kuntz
- Department of Chemistry, Purdue University, West Lafayette, Indiana, USA
| | - Andrew G. McKee
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Wesley D. Penn
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | | | - Douglas B. Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, Indiana, USA
| | - Hope Woods
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee, USA
| | - Dyotima
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
- Institute for Drug Discovery, Leipzig University, Leipzig, SAC, Germany
| | - Jonathan P. Schlebach
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
- Department of Chemistry, Purdue University, West Lafayette, Indiana, USA
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7
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Maes S, Deploey N, Peelman F, Eyckerman S. Deep mutational scanning of proteins in mammalian cells. CELL REPORTS METHODS 2023; 3:100641. [PMID: 37963462 PMCID: PMC10694495 DOI: 10.1016/j.crmeth.2023.100641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 07/06/2023] [Accepted: 10/20/2023] [Indexed: 11/16/2023]
Abstract
Protein mutagenesis is essential for unveiling the molecular mechanisms underlying protein function in health, disease, and evolution. In the past decade, deep mutational scanning methods have evolved to support the functional analysis of nearly all possible single-amino acid changes in a protein of interest. While historically these methods were developed in lower organisms such as E. coli and yeast, recent technological advancements have resulted in the increased use of mammalian cells, particularly for studying proteins involved in human disease. These advancements will aid significantly in the classification and interpretation of variants of unknown significance, which are being discovered at large scale due to the current surge in the use of whole-genome sequencing in clinical contexts. Here, we explore the experimental aspects of deep mutational scanning studies in mammalian cells and report the different methods used in each step of the workflow, ultimately providing a useful guide toward the design of such studies.
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Affiliation(s)
- Stefanie Maes
- VIB Center for Medical Biotechnology (CMB), Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium; Department of Biochemistry and Microbiology, Ghent University, Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium
| | - Nick Deploey
- VIB Center for Medical Biotechnology (CMB), Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium
| | - Frank Peelman
- VIB Center for Medical Biotechnology (CMB), Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium
| | - Sven Eyckerman
- VIB Center for Medical Biotechnology (CMB), Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium; Department of Biomolecular Medicine, Ghent University, Technologiepark-Zwijnaarde 75, 9052 Ghent, Belgium.
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8
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Brandes N, Goldman G, Wang CH, Ye CJ, Ntranos V. Genome-wide prediction of disease variant effects with a deep protein language model. Nat Genet 2023; 55:1512-1522. [PMID: 37563329 PMCID: PMC10484790 DOI: 10.1038/s41588-023-01465-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 62.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 07/05/2023] [Indexed: 08/12/2023]
Abstract
Predicting the effects of coding variants is a major challenge. While recent deep-learning models have improved variant effect prediction accuracy, they cannot analyze all coding variants due to dependency on close homologs or software limitations. Here we developed a workflow using ESM1b, a 650-million-parameter protein language model, to predict all ~450 million possible missense variant effects in the human genome, and made all predictions available on a web portal. ESM1b outperformed existing methods in classifying ~150,000 ClinVar/HGMD missense variants as pathogenic or benign and predicting measurements across 28 deep mutational scan datasets. We further annotated ~2 million variants as damaging only in specific protein isoforms, demonstrating the importance of considering all isoforms when predicting variant effects. Our approach also generalizes to more complex coding variants such as in-frame indels and stop-gains. Together, these results establish protein language models as an effective, accurate and general approach to predicting variant effects.
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Affiliation(s)
- Nadav Brandes
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Grant Goldman
- Biological and Medical Informatics Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Charlotte H Wang
- Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Chun Jimmie Ye
- Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA.
- Parker Institute for Cancer Immunotherapy, University of California, San Francisco, San Francisco, CA, USA.
- Gladstone-UCSF Institute of Genomic Immunology, San Francisco, CA, USA.
- Institute for Human Genetics, University of California, San Francisco, San Francisco, CA, USA.
- Department of Epidemiology & Biostatistics, University of California, San Francisco, San Francisco, CA, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA.
| | - Vasilis Ntranos
- Bakar Computational Health Sciences Institute, University of California, San Francisco, San Francisco, CA, USA.
- Department of Epidemiology & Biostatistics, University of California, San Francisco, San Francisco, CA, USA.
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA.
- Diabetes Center, University of California, San Francisco, San Francisco, CA, USA.
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9
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Nguyen V, Ahler E, Sitko KA, Stephany JJ, Maly DJ, Fowler DM. Molecular determinants of Hsp90 dependence of Src kinase revealed by deep mutational scanning. Protein Sci 2023; 32:e4656. [PMID: 37167432 PMCID: PMC10273359 DOI: 10.1002/pro.4656] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 05/13/2023]
Abstract
Hsp90 is a molecular chaperone involved in the refolding and activation of numerous protein substrates referred to as clients. While the molecular determinants of Hsp90 client specificity are poorly understood and limited to a handful of client proteins, strong clients are thought to be destabilized and conformationally extended. Here, we measured the phosphotransferase activity of 3929 variants of the tyrosine kinase Src in both the presence and absence of an Hsp90 inhibitor. We identified 84 previously unknown functionally dependent client variants. Unexpectedly, many destabilized or extended variants were not functionally dependent on Hsp90. Instead, functionally dependent client variants were clustered in the αF pocket and β1-β2 strand regions of Src, which have yet to be described in driving Hsp90 dependence. Hsp90 dependence was also strongly correlated with kinase activity. We found that a combination of activation, global extension, and general conformational flexibility, primarily induced by variants at the αF pocket and β1-β2 strands, was necessary to render Src functionally dependent on Hsp90. Moreover, the degree of activation and flexibility required to transform Src into a functionally dependent client varied with variant location, suggesting that a combination of regulatory domain disengagement and catalytic domain flexibility are required for chaperone dependence. Thus, by studying the chaperone dependence of a massive number of variants, we highlight factors driving Hsp90 client specificity and propose a model of chaperone-kinase interactions.
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Affiliation(s)
- Vanessa Nguyen
- Department of BioengineeringUniversity of WashingtonSeattleWashingtonUSA
| | - Ethan Ahler
- Department of Genome SciencesUniversity of WashingtonSeattleWashingtonUSA
| | - Katherine A. Sitko
- Department of Genome SciencesUniversity of WashingtonSeattleWashingtonUSA
| | - Jason J. Stephany
- Department of Genome SciencesUniversity of WashingtonSeattleWashingtonUSA
| | - Dustin J. Maly
- Department of ChemistryUniversity of WashingtonSeattleWashingtonUSA
| | - Douglas M. Fowler
- Department of BioengineeringUniversity of WashingtonSeattleWashingtonUSA
- Department of Genome SciencesUniversity of WashingtonSeattleWashingtonUSA
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10
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McKee AG, McDonald EF, Penn WD, Kuntz CP, Noguera K, Chamness LM, Roushar FJ, Meiler J, Oliver KE, Plate L, Schlebach JP. General trends in the effects of VX-661 and VX-445 on the plasma membrane expression of clinical CFTR variants. Cell Chem Biol 2023; 30:632-642.e5. [PMID: 37253358 PMCID: PMC10330547 DOI: 10.1016/j.chembiol.2023.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 02/17/2023] [Accepted: 05/05/2023] [Indexed: 06/01/2023]
Abstract
Cystic fibrosis (CF) is caused by mutations that compromise the expression and/or function of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel. Most people with CF harbor a common misfolded variant (ΔF508) that can be partially rescued by therapeutic "correctors" that restore its expression. Nevertheless, many other CF variants are insensitive to correctors. Using deep mutational scanning, we quantitatively compare the effects of two correctors on the plasma membrane expression of 129 CF variants. Though structural calculations suggest corrector binding provides similar stabilization to most variants, it's those with intermediate expression and mutations near corrector binding pockets that exhibit the greatest response. Deviations in sensitivity appear to depend on the degree of variant destabilization and the timing of misassembly. Combining correctors appears to rescue more variants by doubling the binding energy and stabilizing distinct cotranslational folding transitions. These results provide an overview of rare CF variant expression and establish new tools for precision pharmacology.
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Affiliation(s)
- Andrew G McKee
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Eli F McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Wesley D Penn
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Karen Noguera
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Laura M Chamness
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Francis J Roushar
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA; Institute for Drug Development, Leipzig University, Leipzig, SAC 04109, Germany
| | - Kathryn E Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37232, USA
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11
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Woods H, Schiano DL, Aguirre JI, Ledwitch KV, McDonald EF, Voehler M, Meiler J, Schoeder CT. Computational modeling and prediction of deletion mutants. Structure 2023; 31:713-723.e3. [PMID: 37119820 PMCID: PMC10247520 DOI: 10.1016/j.str.2023.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/02/2023] [Accepted: 04/05/2023] [Indexed: 05/01/2023]
Abstract
In-frame deletion mutations can result in disease. The impact of these mutations on protein structure and subsequent functional changes remain understudied, partially due to the lack of comprehensive datasets including a structural readout. In addition, the recent breakthrough in structure prediction through deep learning demands an update of computational deletion mutation prediction. In this study, we deleted individually every residue of a small α-helical sterile alpha motif domain and investigated the structural and thermodynamic changes using 2D NMR spectroscopy and differential scanning fluorimetry. Then, we tested computational protocols to model and classify observed deletion mutants. We show a method using AlphaFold2 followed by RosettaRelax performs the best overall. In addition, a metric containing pLDDT values and Rosetta ΔΔG is most reliable in classifying tolerated deletion mutations. We further test this method on other datasets and show they hold for proteins known to harbor disease-causing deletion mutations.
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Affiliation(s)
- Hope Woods
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37235, USA
| | - Dominic L Schiano
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Jonathan I Aguirre
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Kaitlyn V Ledwitch
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Eli F McDonald
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Markus Voehler
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Jens Meiler
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; Institute for Drug Discovery, Leipzig University Medical School, 04103 Leipzig, Germany.
| | - Clara T Schoeder
- Center of Structural Biology, Vanderbilt University, Nashville, TN 37235, USA; Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA; Institute for Drug Discovery, Leipzig University Medical School, 04103 Leipzig, Germany.
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12
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Ortega JT, McKee AG, Roushar FJ, Penn WD, Schlebach JP, Jastrzebska B. Chromenone derivatives as novel pharmacological chaperones for retinitis pigmentosa-linked rod opsin mutants. Hum Mol Genet 2022; 31:3439-3457. [PMID: 35642742 PMCID: PMC9558842 DOI: 10.1093/hmg/ddac125] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/14/2022] Open
Abstract
The correct expression of folded, functional rhodopsin (Rho) is critical for visual perception. However, this seven-transmembrane helical G protein-coupled receptor is prone to mutations with pathological consequences of retinal degeneration in retinitis pigmentosa (RP) due to Rho misfolding. Pharmacological chaperones that stabilize the inherited Rho variants by assisting their folding and membrane targeting could slow the progression of RP. In this study, we employed virtual screening of synthetic compounds with a natural product scaffold in conjunction with in vitro and in vivo evaluations to discover a novel chromenone-containing small molecule with favorable pharmacological properties that stabilize rod opsin. This compound reversibly binds to unliganded bovine rod opsin with an EC50 value comparable to the 9-cis-retinal chromophore analog and partially rescued membrane trafficking of multiple RP-related rod opsin variants in vitro. Importantly, this novel ligand of rod opsin was effective in vivo in murine models, protecting photoreceptors from deterioration caused by either bright light or genetic insult. Together, our current study suggests potential broad therapeutic implications of the new chromenone-containing non-retinoid small molecule against retinal diseases associated with photoreceptor degeneration.
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Affiliation(s)
- Joseph T Ortega
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Andrew G McKee
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Francis J Roushar
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Wesley D Penn
- Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA
| | - Jonathan P Schlebach
- To whom correspondence should be addressed at: Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 441064965, USA. Tel: +1 2163685683; Fax: +1 2163681300; (Beata Jastrzebska); Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA. Tel: +1 812-855-6779; Fax: +1 812-855-8300; (Jonathan P. Schlebach)
| | - Beata Jastrzebska
- To whom correspondence should be addressed at: Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 441064965, USA. Tel: +1 2163685683; Fax: +1 2163681300; (Beata Jastrzebska); Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405-7102, USA. Tel: +1 812-855-6779; Fax: +1 812-855-8300; (Jonathan P. Schlebach)
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13
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Molecular Basis for Variations in the Sensitivity of Pathogenic Rhodopsin Variants to 9-cis-Retinal. J Biol Chem 2022; 298:102266. [PMID: 35850308 PMCID: PMC9399271 DOI: 10.1016/j.jbc.2022.102266] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 11/24/2022] Open
Abstract
Over 100 mutations in the rhodopsin gene have been linked to a spectrum of retinopathies that include retinitis pigmentosa and congenital stationary night blindness. Though most of these variants exhibit a loss of function, the molecular defects caused by these underlying mutations vary considerably. In this work, we utilize deep mutational scanning to quantitatively compare the plasma membrane expression of 123 known pathogenic rhodopsin variants in the presence and absence of the stabilizing cofactor 9-cis-retinal. We identify 69 retinopathy variants, including 20 previously uncharacterized variants, that exhibit diminished plasma membrane expression in HEK293T cells. Of these apparent class II variants, 67 exhibit a measurable increase in expression in the presence of 9-cis-retinal. However, the magnitude of the response to this molecule varies considerably across this spectrum of mutations. Evaluation of the observed shifts relative to thermodynamic estimates for the coupling between binding and folding suggests underlying differences in stability constrains the magnitude of their response to retinal. Nevertheless, estimates from computational modeling suggest that many of the least sensitive variants also directly compromise binding. Finally, we evaluate the functional properties of three previous uncharacterized, retinal-sensitive variants (ΔN73, S131P, and R135G) and show that two of these retain residual function in vitro. Together, our results provide a comprehensive experimental characterization of the proteostatic properties of retinopathy variants and their response to retinal.
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14
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Kuntz CP, Woods H, McKee AG, Zelt NB, Mendenhall JL, Meiler J, Schlebach JP. Towards generalizable predictions for G protein-coupled receptor variant expression. Biophys J 2022; 121:2712-2720. [PMID: 35715957 DOI: 10.1016/j.bpj.2022.06.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 05/31/2022] [Accepted: 06/13/2022] [Indexed: 11/30/2022] Open
Abstract
Missense mutations that compromise the plasma membrane expression (PME) of integral membrane proteins are the root cause of numerous genetic diseases. Differentiation of this class of mutations from those that specifically modify the activity of the folded protein has proven useful for the development and targeting of precision therapeutics. Nevertheless, it remains challenging to predict the effects of mutations on the stability and/ or expression of membrane proteins. In this work, we utilize deep mutational scanning data to train a series of artificial neural networks to predict the PME of transmembrane domain variants of G protein-coupled receptors from structural and/ or evolutionary features. We show that our best-performing network, which we term the PME predictor, can recapitulate mutagenic trends within rhodopsin and can differentiate pathogenic transmembrane domain variants that cause it to misfold from those that compromise its signaling. This network also generates statistically significant predictions for the relative PME of transmembrane domain variants for another class A G protein-coupled receptor (β2 adrenergic receptor) but not for an unrelated voltage-gated potassium channel (KCNQ1). Notably, our analyses of these networks suggest structural features alone are generally sufficient to recapitulate the observed mutagenic trends. Moreover, our findings imply that networks trained in this manner may be generalizable to proteins that share a common fold. Implications of our findings for the design of mechanistically specific genetic predictors are discussed.
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Affiliation(s)
- Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, Indiana
| | - Hope Woods
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee
| | - Andrew G McKee
- Department of Chemistry, Indiana University, Bloomington, Indiana
| | - Nathan B Zelt
- Department of Chemistry, Indiana University, Bloomington, Indiana
| | - Jeffrey L Mendenhall
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Saxony, Germany.
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15
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The endoplasmic reticulum proteostasis network profoundly shapes the protein sequence space accessible to HIV envelope. PLoS Biol 2022; 20:e3001569. [PMID: 35180219 PMCID: PMC8906867 DOI: 10.1371/journal.pbio.3001569] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 03/09/2022] [Accepted: 02/07/2022] [Indexed: 12/27/2022] Open
Abstract
The sequence space accessible to evolving proteins can be enhanced by cellular chaperones that assist biophysically defective clients in navigating complex folding landscapes. It is also possible, at least in theory, for proteostasis mechanisms that promote strict quality control to greatly constrain accessible protein sequence space. Unfortunately, most efforts to understand how proteostasis mechanisms influence evolution rely on artificial inhibition or genetic knockdown of specific chaperones. The few experiments that perturb quality control pathways also generally modulate the levels of only individual quality control factors. Here, we use chemical genetic strategies to tune proteostasis networks via natural stress response pathways that regulate the levels of entire suites of chaperones and quality control mechanisms. Specifically, we upregulate the unfolded protein response (UPR) to test the hypothesis that the host endoplasmic reticulum (ER) proteostasis network shapes the sequence space accessible to human immunodeficiency virus-1 (HIV-1) envelope (Env) protein. Elucidating factors that enhance or constrain Env sequence space is critical because Env evolves extremely rapidly, yielding HIV strains with antibody- and drug-escape mutations. We find that UPR-mediated upregulation of ER proteostasis factors, particularly those controlled by the IRE1-XBP1s UPR arm, globally reduces Env mutational tolerance. Conserved, functionally important Env regions exhibit the largest decreases in mutational tolerance upon XBP1s induction. Our data indicate that this phenomenon likely reflects strict quality control endowed by XBP1s-mediated remodeling of the ER proteostasis environment. Intriguingly, and in contrast, specific regions of Env, including regions targeted by broadly neutralizing antibodies, display enhanced mutational tolerance when XBP1s is induced, hinting at a role for host proteostasis network hijacking in potentiating antibody escape. These observations reveal a key function for proteostasis networks in decreasing instead of expanding the sequence space accessible to client proteins, while also demonstrating that the host ER proteostasis network profoundly shapes the mutational tolerance of Env in ways that could have important consequences for HIV adaptation. The host cell’s endoplasmic reticulum proteostasis network has a profound, constraining impact on the protein sequence space accessible to HIV’s envelope protein, which is a major target of the host’s adaptive immune system; in particular, upregulation of stringent quality control pathways appears to restrict the viability of destabilizing envelope variants.
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16
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Dubé AK, Dandage R, Dibyachintan S, Dionne U, Després PC, Landry CR. Deep Mutational Scanning of Protein-Protein Interactions Between Partners Expressed from Their Endogenous Loci In Vivo. Methods Mol Biol 2022; 2477:237-259. [PMID: 35524121 DOI: 10.1007/978-1-0716-2257-5_14] [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: 06/14/2023]
Abstract
Deep mutational scanning (DMS) generates mutants of a protein of interest in a comprehensive manner. CRISPR-Cas9 technology enables large-scale genome editing with high efficiency. Using both DMS and CRISPR-Cas9 therefore allows us to investigate the effects of thousands of mutations inserted directly in the genome. Combined with protein-fragment complementation assay (PCA), which enables the quantitative measurement of protein-protein interactions (PPIs) in vivo, these methods allow for the systematic assessment of the effects of mutations on PPIs in living cells. Here, we describe a method leveraging DMS, CRISPR-Cas9, and PCA to study the effect of point mutations on PPIs mediated by protein domains in yeast.
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Affiliation(s)
- Alexandre K Dubé
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada.
- PROTEO, le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec, QC, Canada.
- Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, QC, Canada.
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada.
- Département de Biologie, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada.
| | - Rohan Dandage
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada
- PROTEO, le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec, QC, Canada
- Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, QC, Canada
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada
- Département de Biologie, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada
| | - Soham Dibyachintan
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada
- PROTEO, le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec, QC, Canada
- Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, QC, Canada
- Département de Biologie, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada
- Department of Chemical Engineering, Indian Institute of Technology Bombay (IIT), Powai, Mumbai, Maharashtra, India
| | - Ugo Dionne
- PROTEO, le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec, QC, Canada
- Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, QC, Canada
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada
- Centre de recherche du Centre Hospitalier Universitaire (CHU) de Québec, Université Laval, Québec, QC, Canada
- Centre de recherche sur le cancer de l'Université Laval, Québec, QC, Canada
| | - Philippe C Després
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada
- PROTEO, le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec, QC, Canada
- Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, QC, Canada
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada
| | - Christian R Landry
- Département de Biochimie, Microbiologie et Bio-informatique, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada.
- PROTEO, le regroupement québécois de recherche sur la fonction, l'ingénierie et les applications des protéines, Université Laval, Québec, QC, Canada.
- Centre de Recherche en Données Massives (CRDM), Université Laval, Québec, QC, Canada.
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada.
- Département de Biologie, Faculté de Sciences et Génie, Université Laval, Québec, QC, Canada.
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17
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Carmody PJ, Zimmer MH, Kuntz CP, Harrington HR, Duckworth K, Penn W, Mukhopadhyay S, Miller T, Schlebach J. Coordination of -1 programmed ribosomal frameshifting by transcript and nascent chain features revealed by deep mutational scanning. Nucleic Acids Res 2021; 49:12943-12954. [PMID: 34871407 PMCID: PMC8682741 DOI: 10.1093/nar/gkab1172] [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: 04/07/2021] [Revised: 10/22/2021] [Accepted: 11/10/2021] [Indexed: 12/17/2022] Open
Abstract
Programmed ribosomal frameshifting (PRF) is a translational recoding mechanism that enables the synthesis of multiple polypeptides from a single transcript. During translation of the alphavirus structural polyprotein, the efficiency of -1PRF is coordinated by a 'slippery' sequence in the transcript, an adjacent RNA stem-loop, and a conformational transition in the nascent polypeptide chain. To characterize each of these effectors, we measured the effects of 4530 mutations on -1PRF by deep mutational scanning. While most mutations within the slip-site and stem-loop reduce the efficiency of -1PRF, the effects of mutations upstream of the slip-site are far more variable. We identify several regions where modifications of the amino acid sequence of the nascent polypeptide impact the efficiency of -1PRF. Molecular dynamics simulations of polyprotein biogenesis suggest the effects of these mutations primarily arise from their impacts on the mechanical forces that are generated by the translocon-mediated cotranslational folding of the nascent polypeptide chain. Finally, we provide evidence suggesting that the coupling between cotranslational folding and -1PRF depends on the translation kinetics upstream of the slip-site. These findings demonstrate how -1PRF is coordinated by features within both the transcript and nascent chain.
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Affiliation(s)
- Patrick J Carmody
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Matthew H Zimmer
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | | | - Kate E Duckworth
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Wesley D Penn
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | | | - Thomas F Miller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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18
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Chamness LM, Zelt NB, Harrington HR, Kuntz CP, Bender BJ, Penn WD, Ziarek JJ, Meiler J, Schlebach JP. Molecular basis for the evolved instability of a human G-protein coupled receptor. Cell Rep 2021; 37:110046. [PMID: 34818554 PMCID: PMC8865034 DOI: 10.1016/j.celrep.2021.110046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 08/06/2021] [Accepted: 11/01/2021] [Indexed: 11/26/2022] Open
Abstract
Membrane proteins are prone to misfolding and degradation. This is particularly true for mammalian forms of the gonadotropin-releasing hormone receptor (GnRHR). Although they function at the plasma membrane, mammalian GnRHRs accumulate within the secretory pathway. Their apparent instability is believed to have evolved through selection for attenuated GnRHR activity. Nevertheless, the molecular basis of this adaptation remains unclear. We show that adaptation coincides with a C-terminal truncation that compromises the translocon-mediated membrane integration of its seventh transmembrane domain (TM7). We also identify a series of polar residues in mammalian GnRHRs that compromise the membrane integration of TM2 and TM6. Reverting a lipid-exposed polar residue in TM6 to an ancestral hydrophobic residue restores expression with no impact on function. Evolutionary trends suggest variations in the polarity of this residue track with reproductive phenotypes. Our findings suggest that the marginal energetics of cotranslational folding can be exploited to tune membrane protein fitness. Integral membrane proteins are prone to misfolding, especially mammalian gonadotropin-releasing hormone receptors (GnRHRs). Chamness et al. show that the evolved instability of mammalian GnRHRs stems from adaptive modifications that disrupt translocon-mediated membrane integration, suggesting that membrane protein misfolding can be exploited to tune fitness.
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Affiliation(s)
- Laura M Chamness
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Nathan B Zelt
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | | | - Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Brian J Bender
- Department of Chemistry, Vanderbilt University, Nashville, TN 49795, USA
| | - Wesley D Penn
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Joshua J Ziarek
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 49795, USA; Institut for Drug Development, Leipzig University, Leipzig, SAC, Germany
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19
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McKee AG, Kuntz CP, Ortega JT, Woods H, Most V, Roushar FJ, Meiler J, Jastrzebska B, Schlebach JP. Systematic Profiling of Temperature- and Retinal-Sensitive Rhodopsin Variants by Deep Mutational Scanning. J Biol Chem 2021; 297:101359. [PMID: 34756884 PMCID: PMC8649220 DOI: 10.1016/j.jbc.2021.101359] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 10/20/2021] [Accepted: 10/26/2021] [Indexed: 01/29/2023] Open
Abstract
Membrane protein variants with diminished conformational stability often exhibit enhanced cellular expression at reduced growth temperatures. The expression of “temperature-sensitive” variants is also typically sensitive to corrector molecules that bind and stabilize the native conformation. There are many examples of temperature-sensitive rhodopsin variants, the misfolding of which is associated with the molecular basis of retinitis pigmentosa. In this work, we employ deep mutational scanning to compare the effects of reduced growth temperature and 9-cis-retinal, an investigational corrector, on the plasma membrane expression of 700 rhodopsin variants in HEK293T cells. We find that the change in expression at reduced growth temperatures correlates with the response to 9-cis-retinal among variants bearing mutations within a hydrophobic transmembrane domain (TM2). The most sensitive variants appear to disrupt a native helical kink within this transmembrane domain. By comparison, mutants that alter the structure of a polar transmembrane domain (TM7) exhibit weaker responses to temperature and retinal that are poorly correlated. Statistical analyses suggest that this observed insensitivity cannot be attributed to a single variable, but likely arises from the composite effects of mutations on the energetics of membrane integration, the stability of the native conformation, and the integrity of the retinal-binding pocket. Finally, we show that the characteristics of purified temperature- and retinal-sensitive variants suggest that the proteostatic effects of retinal may be manifested during translation and cotranslational folding. Together, our findings highlight several biophysical constraints that appear to influence the sensitivity of genetic variants to temperature and small-molecule correctors.
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Affiliation(s)
- Andrew G McKee
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Charles P Kuntz
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Joseph T Ortega
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
| | - Hope Woods
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee, USA
| | - Victoria Most
- Institute for Drug Development, Leipzig University, Leipzig, SAC, Germany
| | - Francis J Roushar
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Institute for Drug Development, Leipzig University, Leipzig, SAC, Germany
| | - Beata Jastrzebska
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, USA
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20
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Marx DC, Fleming KG. Membrane proteins enter the fold. Curr Opin Struct Biol 2021; 69:124-130. [PMID: 33975156 DOI: 10.1016/j.sbi.2021.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/15/2021] [Accepted: 03/21/2021] [Indexed: 11/19/2022]
Abstract
Membrane proteins have historically been recalcitrant to biophysical folding studies. However, recent adaptations of methods from the soluble protein folding field have found success in their applications to transmembrane proteins composed of both α-helical and β-barrel conformations. Avoiding aggregation is critical for the success of these experiments. Altogether these studies are leading to discoveries of folding trajectories, foundational stabilizing forces and better-defined endpoints that enable more accurate interpretation of thermodynamic data. Increased information on membrane protein folding in the cell shows that the emerging biophysical principles are largely recapitulated even in the complex biological environment.
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Affiliation(s)
- Dagan C Marx
- TC Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, United States
| | - Karen G Fleming
- TC Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, United States.
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21
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Jia X, Burugula BB, Chen V, Lemons RM, Jayakody S, Maksutova M, Kitzman JO. Massively parallel functional testing of MSH2 missense variants conferring Lynch syndrome risk. Am J Hum Genet 2021; 108:163-175. [PMID: 33357406 PMCID: PMC7820803 DOI: 10.1016/j.ajhg.2020.12.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/03/2020] [Indexed: 12/20/2022] Open
Abstract
The lack of functional evidence for the majority of missense variants limits their clinical interpretability and poses a key barrier to the broad utility of carrier screening. In Lynch syndrome (LS), one of the most highly prevalent cancer syndromes, nearly 90% of clinically observed missense variants are deemed “variants of uncertain significance” (VUS). To systematically resolve their functional status, we performed a massively parallel screen in human cells to identify loss-of-function missense variants in the key DNA mismatch repair factor MSH2. The resulting functional effect map is substantially complete, covering 94% of the 17,746 possible variants, and is highly concordant (96%) with existing functional data and expert clinicians’ interpretations. The large majority (89%) of missense variants were functionally neutral, perhaps unexpectedly in light of its evolutionary conservation. These data provide ready-to-use functional evidence to resolve the ∼1,300 extant missense VUSs in MSH2 and may facilitate the prospective classification of newly discovered variants in the clinic.
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Srikant S. Evolutionary history of ATP-binding cassette proteins. FEBS Lett 2020; 594:3882-3897. [PMID: 33145769 DOI: 10.1002/1873-3468.13985] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 10/01/2020] [Accepted: 10/15/2020] [Indexed: 12/11/2022]
Abstract
ATP-binding cassette (ABC) proteins are found in every sequenced genome and evolved deep in the phylogenetic tree of life. ABC proteins form one of the largest homologous protein families, with most being involved in substrate transport across biological membranes, and a few cytoplasmic members regulating in essential processes like translation. The predominant ABC protein classification scheme is derived from human members, but the increasing number of fully sequenced genomes permits to reevaluate this paradigm in the light of the evolutionary history the ABC-protein superfamily. As we study the diversity of substrates, mechanisms, and physiological roles of ABC proteins, knowledge of the evolutionary relationships highlights similarities and differences that can be attributed to specific branches in protein divergence. While alignments and trees built on natural sequence variation account for the evolutionary divergence of ABC proteins, high-throughput experiments and next-generation sequencing creating experimental sequence variation are instrumental in identifying functional constraints. The combination of natural and experimentally produced sequence variation allows a broader and more rational study of the function and physiological roles of ABC proteins.
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Affiliation(s)
- Sriram Srikant
- Department of Biology, Massachusetts Institute of Technology
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