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McDonald EF, Kim M, Olson JA, Meiler J, Plate L. Proteostasis Landscapes of Selective versus Poorly Responsive CFTR Variants Reveals Structural Vulnerabilities to Correction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.10.602964. [PMID: 39026768 PMCID: PMC11257600 DOI: 10.1101/2024.07.10.602964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Cystic Fibrosis (CF) is a lethal genetic disorder caused by variants in CF transmembrane conductance regulator (CFTR). Many disease variants are treatable with corrector compounds, which enhance the folding and trafficking of CFTR. However, correctors fail to elicit a response for every CFTR variant. Approximately 3% of persons with CF harbor poorly responsive CFTR variants. Here, we reveal that a group of poorly responsive variants overlap with selectively responsive variants in a critical domain interface (nucleotide-binding domain 1/intracellular loop 4 - NBD1/ICL4). Affinity purification mass spectrometry proteomics was used to profile the protein homeostasis (proteostasis) changes of CFTR variants during corrector treatment to assess modulated interactions with protein folding and maturation pathways. Responsive variant interactions converged on similar proteostasis pathways during correction. In contrast, poorly responsive variants subtly diverged, revealing a partial restoration of protein quality control surveillance and a capacity to correct some mutations. Computational structural modeling showed that corrector VX-445 failed to confer enough NBD1 stability to poorly responsive variants. NBD1 secondary stabilizing mutations rescued poorly responsive variants, revealing structural vulnerabilities in NBD1 required for treating poor responders. Our study provides a framework for discerning the underlying protein quality control and structural defects of CFTR variants not reached with existing drugs. These insights can help expand therapeutics to all susceptible CFTR variants to enhance personalized medicine efforts.
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Affiliation(s)
- Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Minsoo Kim
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37240, USA
| | - John A Olson
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN 37240, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
- Institute for Drug Discovery, Leipzig University, Leipzig, SAC 04103, Germany
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37240, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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2
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McDonald EF, Oliver KE, Schlebach JP, Meiler J, Plate L. Benchmarking AlphaMissense pathogenicity predictions against cystic fibrosis variants. PLoS One 2024; 19:e0297560. [PMID: 38271453 PMCID: PMC10810519 DOI: 10.1371/journal.pone.0297560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/08/2024] [Indexed: 01/27/2024] Open
Abstract
Variants in the cystic fibrosis transmembrane conductance regulator gene (CFTR) result in cystic fibrosis-a lethal autosomal recessive disorder. Missense variants that alter a single amino acid in the CFTR protein are among the most common cystic fibrosis variants, yet tools for accurately predicting molecular consequences of missense variants have been limited to date. AlphaMissense (AM) is a new technology that predicts the pathogenicity of missense variants based on dual learned protein structure and evolutionary features. Here, we evaluated the ability of AM to predict the pathogenicity of CFTR missense variants. AM predicted a high pathogenicity for CFTR residues overall, resulting in a high false positive rate and fair classification performance on CF variants from the CFTR2.org database. AM pathogenicity score correlated modestly with pathogenicity metrics from persons with CF including sweat chloride level, pancreatic insufficiency rate, and Pseudomonas aeruginosa infection rate. Correlation was also modest with CFTR trafficking and folding competency in vitro. By contrast, the AM score correlated well with CFTR channel function in vitro-demonstrating the dual structure and evolutionary training approach learns important functional information despite lacking such data during training. Different performance across metrics indicated AM may determine if polymorphisms in CFTR are recessive CF variants yet cannot differentiate mechanistic effects or the nature of pathophysiology. Finally, AM predictions offered limited utility to inform on the pharmacological response of CF variants i.e., theratype. Development of new approaches to differentiate the biochemical and pharmacological properties of CFTR variants is therefore still needed to refine the targeting of emerging precision CF therapeutics.
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Affiliation(s)
- Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kathryn E. Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
- Center for Cystic Fibrosis and Airways Diseases, Children’s Healthcare of Atlanta and Emory University, Atlanta, Georgia, United States of America
| | - Jonathan P. Schlebach
- Department of Chemistry, Purdue University, West Lafyette, Indiana, United States of America
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Institute for Drug Discovery, Leipzig University, Leipzig, Germany
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
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3
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McDonald EF, Oliver KE, Schlebach JP, Meiler J, Plate L. Benchmarking AlphaMissense Pathogenicity Predictions Against Cystic Fibrosis Variants. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.05.561147. [PMID: 37873426 PMCID: PMC10592606 DOI: 10.1101/2023.10.05.561147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Variants in the cystic fibrosis transmembrane conductance regulator gene (CFTR) result in cystic fibrosis - a lethal autosomal recessive disorder. Missense variants that alter a single amino acid in the CFTR protein are among the most common cystic fibrosis variants, yet tools for accurately predicting molecular consequences of missense variants have been limited to date. AlphaMissense (AM) is a new technology that predicts the pathogenicity of missense variants based on dual learned protein structure and evolutionary features. Here, we evaluated the ability of AM to predict the pathogenicity of CFTR missense variants. AM predicted a high pathogenicity for CFTR residues overall, resulting in a high false positive rate and fair classification performance on CF variants from the CFTR2.org database. AM pathogenicity score correlated modestly with pathogenicity metrics from persons with CF including sweat chloride level, pancreatic insufficiency rate, and Pseudomonas aeruginosa infection rate. Correlation was also modest with CFTR trafficking and folding competency in vitro. By contrast, the AM score correlated well with CFTR channel function in vitro - demonstrating the dual structure and evolutionary training approach learns important functional information despite lacking such data during training. Different performance across metrics indicated AM may determine if polymorphisms in CFTR are recessive CF variants yet cannot differentiate mechanistic effects or the nature of pathophysiology. Finally, AM predictions offered limited utility to inform on the pharmacological response of CF variants i.e., theratype. Development of new approaches to differentiate the biochemical and pharmacological properties of CFTR variants is therefore still needed to refine the targeting of emerging precision CF therapeutics.
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Affiliation(s)
- Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Kathryn E. Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
- Center for Cystic Fibrosis and Airways Diseases, Children’s Healthcare of Atlanta and Emory University, Atlanta, GA 30322, USA
| | | | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
- Institute for Drug Discovery, Leipzig University, Leipzig, SAC 04103, Germany
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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4
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Selvasingh JA, McDonald EF, Neufer PD, McKinney JR, Meiler J, Ledwitch KV. Dark nanodiscs for evaluating membrane protein thermostability by differential scanning fluorimetry. Biophys J 2024; 123:68-79. [PMID: 37978799 PMCID: PMC10808023 DOI: 10.1016/j.bpj.2023.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 10/27/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023] Open
Abstract
Measuring protein thermostability provides valuable information on the biophysical rules that govern the structure-energy relationships of proteins. However, such measurements remain a challenge for membrane proteins. Here, we introduce a new experimental system to evaluate membrane protein thermostability. This system leverages a recently developed nonfluorescent membrane scaffold protein to reconstitute proteins into nanodiscs and is coupled with a nano-format of differential scanning fluorimetry (nanoDSF). This approach offers a label-free and direct measurement of the intrinsic tryptophan fluorescence of the membrane protein as it unfolds in solution without signal interference from the "dark" nanodisc. In this work, we demonstrate the application of this method using the disulfide bond formation protein B (DsbB) as a test membrane protein. NanoDSF measurements of DsbB reconstituted in dark nanodiscs loaded with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phosphorylglycerol (DMPG) lipids show a complex biphasic thermal unfolding pattern with a minor unfolding transition followed by a major transition. The inflection points of the thermal denaturation curve reveal two distinct unfolding midpoint melting temperatures (Tm) of 70.5°C and 77.5°C, consistent with a three-state unfolding model. Further, we show that the catalytically conserved disulfide bond between residues C41 and C130 drives the intermediate state of the unfolding pathway for DsbB in a DMPC and DMPG nanodisc. To extend the utility of this method, we evaluate and compare the thermostability of DsbB in different lipid environments. We introduce this method as a new tool that can be used to understand how compositionally and biophysically complex lipid environments drive membrane protein stability.
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Affiliation(s)
- Jazlyn A Selvasingh
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Eli F McDonald
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Preston D Neufer
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Jacob R McKinney
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute of Drug Discovery, Faculty of Medicine, University of Leipzig, Leipzig, Germany.
| | - Kaitlyn V Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee; Department of Chemistry, Vanderbilt University, Nashville, Tennessee.
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5
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McDonald EF, Meiler J, Plate L. CFTR Folding: From Structure and Proteostasis to Cystic Fibrosis Personalized Medicine. ACS Chem Biol 2023; 18:2128-2143. [PMID: 37730207 PMCID: PMC10595991 DOI: 10.1021/acschembio.3c00310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 08/02/2023] [Indexed: 09/22/2023]
Abstract
Cystic fibrosis (CF) is a lethal genetic disease caused by mutations in the chloride ion channel cystic fibrosis transmembrane conductance regulator (CFTR). Class-II mutants of CFTR lack intermolecular interactions important for CFTR structural stability and lead to misfolding. Misfolded CFTR is detected by a diverse suite of proteostasis factors that preferentially bind and route mutant CFTR toward premature degradation, resulting in reduced plasma membrane CFTR levels and impaired chloride ion conductance associated with CF. CF treatment has been vastly improved over the past decade by the availability of small molecules called correctors. Correctors directly bind CFTR, stabilize its structure by conferring thermodynamically favorable interactions that compensate for mutations, and thereby lead to downstream folding fidelity. However, each of over 100 Class-II CF causing mutations causes unique structural defects and shows a unique response to drug treatment, described as theratype. Understanding CFTR structural defects, the proteostasis factors evaluating those defects, and the stabilizing effects of CFTR correctors will illuminate a path toward personalized medicine for CF. Here, we review recent advances in our understanding of CFTR folding, focusing on structure, corrector binding sites, the mechanisms of proteostasis factors that evaluate CFTR, and the implications for CF personalized medicine.
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Affiliation(s)
- Eli Fritz McDonald
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
| | - Jens Meiler
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Center
for Structural Biology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Department
of Pharmacology, Vanderbilt University, Nashville, Tennessee 37240, United States
- Institute
for Drug Discovery, Leipzig University, Leipzig, SAC 04103, Germany
| | - Lars Plate
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37235, United States
- Department
of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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6
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Lester A, Sandman M, Herring C, Girard C, Dixon B, Ramsdell H, Reber C, Poulos J, Mitchell A, Spinney A, Henager ME, Evans CN, Turlington M, Johnson QR. Computational Exploration of Potential CFTR Binding Sites for Type I Corrector Drugs. Biochemistry 2023; 62:2503-2515. [PMID: 37437308 PMCID: PMC10433520 DOI: 10.1021/acs.biochem.3c00165] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/22/2023] [Indexed: 07/14/2023]
Abstract
Cystic fibrosis (CF) is a recessive genetic disease that is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The recent development of a class of drugs called "correctors", which repair the structure and function of mutant CFTR, has greatly enhanced the life expectancy of CF patients. These correctors target the most common disease causing CFTR mutant F508del and are exemplified by the FDA-approved VX-809. While one binding site of VX-809 to CFTR was recently elucidated by cryo-electron microscopy, four additional binding sites have been proposed in the literature and it has been theorized that VX-809 and structurally similar correctors may engage multiple CFTR binding sites. To explore these five binding sites, ensemble docking was performed on wild-type CFTR and the F508del mutant using a large library of structurally similar corrector drugs, including VX-809 (lumacaftor), VX-661 (tezacaftor), ABBV-2222 (galicaftor), and a host of other structurally related molecules. For wild-type CFTR, we find that only one site, located in membrane spanning domain 1 (MSD1), binds favorably to our ligand library. While this MSD1 site also binds our ligand library for F508del-CFTR, the F508del mutation also opens a binding site in nucleotide binding domain 1 (NBD1), which enables strong binding of our ligand library to this site. This NBD1 site in F508del-CFTR exhibits the strongest overall binding affinity for our library of corrector drugs. This data may serve to better understand the structural changes induced by mutation of CFTR and how correctors bind to the protein. Additionally, it may aid in the design of new, more effective CFTR corrector drugs.
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Affiliation(s)
- Anna Lester
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Madeline Sandman
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Caitlin Herring
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Christian Girard
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Brandon Dixon
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Havanna Ramsdell
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Callista Reber
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Jack Poulos
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Alexis Mitchell
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Allison Spinney
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Marissa E. Henager
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Claudia N. Evans
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Mark Turlington
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
| | - Quentin R. Johnson
- Berry College Department
of Chemistry and Biochemistry, Mount Berry, Georgia 30149, United States
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7
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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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8
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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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9
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Selvasingh JA, McDonald EF, Mckinney JR, Meiler J, Ledwitch KV. Dark nanodiscs as a model membrane for evaluating membrane protein thermostability by differential scanning fluorimetry. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539917. [PMID: 37214798 PMCID: PMC10197605 DOI: 10.1101/2023.05.08.539917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Measuring protein thermostability provides valuable information on the biophysical rules that govern structure-energy relationships of proteins. However, such measurements remain a challenge for membrane proteins. Here, we introduce a new experimental system to evaluate membrane protein thermostability. This system leverages a recently-developed non-fluorescent membrane scaffold protein (MSP) to reconstitute proteins into nanodiscs and is coupled with a nano-format of differential scanning fluorimetry (nanoDSF). This approach offers a label-free and direct measurement of the intrinsic tryptophan fluorescence of the membrane protein as it unfolds in solution without signal interference from the "dark" nanodisc. In this work, we demonstrate the application of this method using the disulfide bond formation protein B (DsbB) as a test membrane protein. NanoDSF measurements of DsbB reconstituted in dark nanodiscs show a complex biphasic thermal unfolding pattern in the presence of lipids with a minor unfolding transition followed by a major transition. The inflection points of the thermal denaturation curve reveal two distinct unfolding midpoint melting temperatures (Tm) of 70.5 °C and 77.5 °C, consistent with a three-state unfolding model. Further, we show that the catalytically conserved disulfide bond between residues C41 and C130 drives the intermediate state of the unfolding pathway for DsbB in a nanodisc. We introduce this method as a new tool that can be used to understand how compositionally, and biophysically complex lipid environments drive membrane protein stability.
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Affiliation(s)
- Jazlyn A. Selvasingh
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Eli Fritz McDonald
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Jacob R. Mckinney
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Institute of Drug Discovery, Faculty of Medicine, University of Leipzig, 04103 Leipzig, Germany
| | - Kaitlyn V. Ledwitch
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Lead contact
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10
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McDonald EF, Jones T, Plate L, Meiler J, Gulsevin A. Benchmarking AlphaFold2 on peptide structure prediction. Structure 2023; 31:111-119.e2. [PMID: 36525975 PMCID: PMC9883802 DOI: 10.1016/j.str.2022.11.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 10/15/2022] [Accepted: 11/18/2022] [Indexed: 12/23/2022]
Abstract
Recent advancements in computational tools have allowed protein structure prediction with high accuracy. Computational prediction methods have been used for modeling many soluble and membrane proteins, but the performance of these methods in modeling peptide structures has not yet been systematically investigated. We benchmarked the accuracy of AlphaFold2 in predicting 588 peptide structures between 10 and 40 amino acids using experimentally determined NMR structures as reference. Our results showed AlphaFold2 predicts α-helical, β-hairpin, and disulfide-rich peptides with high accuracy. AlphaFold2 performed at least as well if not better than alternative methods developed specifically for peptide structure prediction. AlphaFold2 showed several shortcomings in predicting Φ/Ψ angles, disulfide bond patterns, and the lowest RMSD structures failed to correlate with lowest pLDDT ranked structures. In summary, computation can be a powerful tool to predict peptide structures, but additional steps may be necessary to analyze and validate the results.
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Affiliation(s)
- Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN 37212, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA
| | - Taylor Jones
- Department of Chemistry, Vanderbilt University, Nashville, TN 37212, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN 37212, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37212, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN 37212, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA; Institute for Drug Discovery, Leipzig University Medical School, 04103 Leipzig, Germany.
| | - Alican Gulsevin
- Department of Chemistry, Vanderbilt University, Nashville, TN 37212, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN 37212, USA.
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