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Cui X, Zheng Z, Rahman MU, Hong X, Ji X, Li Z, Chen HF. Drude2019IDPC polarizable force field reveals structure-function relationship of insulin. Int J Biol Macromol 2024; 280:136256. [PMID: 39366599 DOI: 10.1016/j.ijbiomac.2024.136256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Revised: 09/30/2024] [Accepted: 10/01/2024] [Indexed: 10/06/2024]
Abstract
Intrinsically disordered proteins (IDPs) lack stable tertiary structures under physiological conditions, yet play key roles in biological processes and associated with human complex diseases. Their conformational characteristics and high content of charged residues make the use of polarizable force fields an advantageous for simulating IDPs. The Drude2019IDP polarizable force field, previously introduced, has demonstrated comprehensive enhancements and improvements in dipeptides, short peptides, and IDPs, achieving a balanced sampling between IDPs and structured proteins. However, the performance in simulating 5 dipeptides was found to be underestimate. Therefore, we individually performed reweighting and grid-based energy correction map (CMAP) optimization for these 5 dipeptides, resulting in the enhanced Drude2019IDPC force field. The performance of Drude2019IDPC was evaluated with 5 dipeptides, 5 disordered short peptides, and a representative IDP. The results demonstrated a marked improvement comparing with original Drude2019IDP. To further substantiate the capabilities of Drude2019IDPC, MD simulation and Markov state model (MSM) were applied to wild type and mutant for insulin, to elucidate the difference of conformational characteristics and transition path. The findings reveal that mutation can maintain the monomorphic characteristics, providing insights for engineered insulin development. These results indicate that Drude2019IDPC could be used to reveal the structure-function relationship for other proteins.
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Affiliation(s)
- Xiaochen Cui
- State Key Laboratory of Microbial metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhuoqi Zheng
- State Key Laboratory of Microbial metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Mueed Ur Rahman
- State Key Laboratory of Microbial metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaokun Hong
- College of Biological Science and Engineering, Fuzhou University, Fuzhou, Fujian 350116, China
| | - Xiaoyue Ji
- State Key Laboratory of Microbial metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhengxin Li
- State Key Laboratory of Microbial metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hai-Feng Chen
- State Key Laboratory of Microbial metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, Department of Bioinformatics and Biostatistics, National Experimental Teaching Center for Life Sciences and Biotechnology, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.
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Pujahari SR, Purusottam RN, Mali PS, Sarkar S, Khaneja N, Vajpai N, Kumar A. Exploring the Higher Order Structure and Conformational Transitions in Insulin Microcrystalline Biopharmaceuticals by Proton-Detected Solid-State Nuclear Magnetic Resonance at Natural Abundance. Anal Chem 2024; 96:4756-4763. [PMID: 38326990 DOI: 10.1021/acs.analchem.3c04040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
The integrity of a higher order structure (HOS) is an essential requirement to ensure the efficacy, stability, and safety of protein therapeutics. Solution-state nuclear magnetic resonance (NMR) occupies a unique niche as one of the most promising methods to access atomic-level structural information on soluble biopharmaceutical formulations. Another major class of drugs is poorly soluble, such as microcrystalline suspensions, which poses significant challenges for the characterization of the active ingredient in its native state. Here, we have demonstrated a solid-state NMR method for HOS characterization of biopharmaceutical suspensions employing a selective excitation scheme under fast magic angle spinning (MAS). The applicability of the method is shown on commercial insulin suspensions at natural isotopic abundance. Selective excitation aided with proton detection and non-uniform sampling (NUS) provides improved sensitivity and resolution. The enhanced resolution enabled us to demonstrate the first experimental evidence of a phenol-escaping pathway in insulin, leading to conformational transitions to different hexameric states. This approach has the potential to serve as a valuable means for meticulously examining microcrystalline biopharmaceutical suspensions, which was previously not attainable in their native formulation states and can be seamlessly extended to other classes of biopharmaceuticals such as mAbs and other microcrystalline proteins.
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Affiliation(s)
- Soumya Ranjan Pujahari
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai Mumbai 400076, India
| | - Rudra N Purusottam
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai Mumbai 400076, India
| | - Pramod S Mali
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai Mumbai 400076, India
| | - Sambeda Sarkar
- System and Control Engineering, Indian Institute of Technology, Bombay, Powai Mumbai 400076, India
| | - Navin Khaneja
- System and Control Engineering, Indian Institute of Technology, Bombay, Powai Mumbai 400076, India
| | - Navratna Vajpai
- Biocon Biologics Limited, Biocon SEZ, Plot No. 2 & 3, Phase IV-B.I.A, Bommasandra-Jigani Link Road, Bangalore 560099, India
| | - Ashutosh Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai Mumbai 400076, India
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3
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Abstract
Insulin is a peptide hormone essential for maintaining normal blood glucose levels. Individuals unable to secrete sufficient insulin or not able to respond properly to insulin develop diabetes. Since the discovery of insulin its structure and function has been intensively studied with the aim to develop effective diabetes treatments. The three-dimensional crystal structure of this 51 amino acid peptide paved the way for discoveries, outlined in this review, of determinants important for receptor binding and hormone stability that have been instrumental in development of insulin analogs used in the clinic today. Important for the future development of effective diabetes treatments will be a detailed understanding of the insulin receptor structure and function. Determination of the three-dimensional structure of the insulin receptor, a receptor tyrosine kinase, proved challenging but with the recent advent of high-resolution cryo-electron microscopy significant progress has been made. There are now >40 structures of the insulin:insulin receptor complex deposited in the Protein Data Bank. From these structures we have a detailed picture of how insulin binds and activates the receptor. Still lacking are details of the initial binding events and the exact sequence of structural changes within the receptor and insulin. In this review, the focus will be on the most recent structural studies of insulin:insulin receptor complexes and how they have contributed to the current understanding of insulin receptor activation and signaling outcome. Molecular mechanisms underlying insulin receptor signaling bias emerging from the latest structures are described.
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Affiliation(s)
- Briony E Forbes
- Flinders Health and Medical Research Institute, Flinders University, Bedford Park, SA, Australia.
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4
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Turvey SJ, McPhillie MJ, Kearney MT, Muench SP, Simmons KJ, Fishwick CWG. Recent developments in the structural characterisation of the IR and IGF1R: implications for the design of IR-IGF1R hybrid receptor modulators. RSC Med Chem 2022; 13:360-374. [PMID: 35647546 PMCID: PMC9020618 DOI: 10.1039/d1md00300c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 01/12/2022] [Indexed: 12/16/2022] Open
Abstract
The insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF1R) are dimeric disulfide-linked receptor tyrosine kinases, whose actions regulate metabolic and mitogenic signalling pathways inside the cell. It is well documented that in tissues co-expressing the IR and IGF1R, their respective monomers can heterodimerise to form IR-IGF1R hybrid receptors. Increased populations of the IR-IGF1R hybrid receptors are associated with several disease states, including type 2 diabetes and cancer. Recently, progress in the structural biology of IR and IGF1R has given insights into their structure-function relationships and mechanism of action. However, challenges in isolating IR-IGF1R hybrid receptors mean that their structural properties remain relatively unexplored. This review discusses the advances in the structural understanding of the IR and IGF1R, and how these discoveries can inform the design of small-molecule modulators of the IR-IGF1R hybrid receptors to understand their role in cell biology.
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Affiliation(s)
- Samuel J Turvey
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds UK
| | | | - Mark T Kearney
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre, University of Leeds UK
| | - Katie J Simmons
- Leeds Institute for Cardiovascular and Metabolic Medicine, University of Leeds UK
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Jarosinski MA, Chen YS, Varas N, Dhayalan B, Chatterjee D, Weiss MA. New Horizons: Next-Generation Insulin Analogues: Structural Principles and Clinical Goals. J Clin Endocrinol Metab 2022; 107:909-928. [PMID: 34850005 PMCID: PMC8947325 DOI: 10.1210/clinem/dgab849] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Indexed: 11/19/2022]
Abstract
Design of "first-generation" insulin analogues over the past 3 decades has provided pharmaceutical formulations with tailored pharmacokinetic (PK) and pharmacodynamic (PD) properties. Application of a molecular tool kit-integrating protein sequence, chemical modification, and formulation-has thus led to improved prandial and basal formulations for the treatment of diabetes mellitus. Although PK/PD changes were modest in relation to prior formulations of human and animal insulins, significant clinical advantages in efficacy (mean glycemia) and safety (rates of hypoglycemia) were obtained. Continuing innovation is providing further improvements to achieve ultrarapid and ultrabasal analogue formulations in an effort to reduce glycemic variability and optimize time in range. Beyond such PK/PD metrics, next-generation insulin analogues seek to exploit therapeutic mechanisms: glucose-responsive ("smart") analogues, pathway-specific ("biased") analogues, and organ-targeted analogues. Smart insulin analogues and delivery systems promise to mitigate hypoglycemic risk, a critical barrier to glycemic control, whereas biased and organ-targeted insulin analogues may better recapitulate physiologic hormonal regulation. In each therapeutic class considerations of cost and stability will affect use and global distribution. This review highlights structural principles underlying next-generation design efforts, their respective biological rationale, and potential clinical applications.
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Affiliation(s)
- Mark A Jarosinski
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Nicolás Varas
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Deepak Chatterjee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
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6
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Jarosinski MA, Dhayalan B, Chen YS, Chatterjee D, Varas N, Weiss MA. Structural principles of insulin formulation and analog design: A century of innovation. Mol Metab 2021; 52:101325. [PMID: 34428558 PMCID: PMC8513154 DOI: 10.1016/j.molmet.2021.101325] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/12/2021] [Accepted: 08/17/2021] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The discovery of insulin in 1921 and its near-immediate clinical use initiated a century of innovation. Advances extended across a broad front, from the stabilization of animal insulin formulations to the frontiers of synthetic peptide chemistry, and in turn, from the advent of recombinant DNA manufacturing to structure-based protein analog design. In each case, a creative interplay was observed between pharmaceutical applications and then-emerging principles of protein science; indeed, translational objectives contributed to a growing molecular understanding of protein structure, aggregation and misfolding. SCOPE OF REVIEW Pioneering crystallographic analyses-beginning with Hodgkin's solving of the 2-Zn insulin hexamer-elucidated general features of protein self-assembly, including zinc coordination and the allosteric transmission of conformational change. Crystallization of insulin was exploited both as a step in manufacturing and as a means of obtaining protracted action. Forty years ago, the confluence of recombinant human insulin with techniques for site-directed mutagenesis initiated the present era of insulin analogs. Variant or modified insulins were developed that exhibit improved prandial or basal pharmacokinetic (PK) properties. Encouraged by clinical trials demonstrating the long-term importance of glycemic control, regimens based on such analogs sought to resemble daily patterns of endogenous β-cell secretion more closely, ideally with reduced risk of hypoglycemia. MAJOR CONCLUSIONS Next-generation insulin analog design seeks to explore new frontiers, including glucose-responsive insulins, organ-selective analogs and biased agonists tailored to address yet-unmet clinical needs. In the coming decade, we envision ever more powerful scientific synergies at the interface of structural biology, molecular physiology and therapeutics.
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Affiliation(s)
- Mark A Jarosinski
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, 46202, IN, USA
| | - Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, 46202, IN, USA
| | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, 46202, IN, USA
| | - Deepak Chatterjee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, 46202, IN, USA
| | - Nicolás Varas
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, 46202, IN, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, 46202, IN, USA; Department of Chemistry, Indiana University, Bloomington, 47405, IN, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, 47907, IN, USA.
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Dhayalan B, Chatterjee D, Chen YS, Weiss MA. Structural Lessons From the Mutant Proinsulin Syndrome. Front Endocrinol (Lausanne) 2021; 12:754693. [PMID: 34659132 PMCID: PMC8514764 DOI: 10.3389/fendo.2021.754693] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/13/2021] [Indexed: 12/30/2022] Open
Abstract
Insight into folding mechanisms of proinsulin has been provided by analysis of dominant diabetes-associated mutations in the human insulin gene (INS). Such mutations cause pancreatic β-cell dysfunction due to toxic misfolding of a mutant proinsulin and impairment in trans of wild-type insulin secretion. Anticipated by the "Akita" mouse (a classical model of monogenic diabetes mellitus; DM), this syndrome illustrates the paradigm endoreticulum (ER) stress leading to intracellular proteotoxicity. Diverse clinical mutations directly or indirectly perturb native disulfide pairing leading to protein misfolding and aberrant aggregation. Although most introduce or remove a cysteine (Cys; leading in either case to an unpaired thiol group), non-Cys-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the hormone's evolution has been constrained not only by structure-function relationships, but also by the susceptibility of its single-chain precursor to impaired foldability. An intriguing hypothesis posits that INS overexpression in response to peripheral insulin resistance likewise leads to chronic ER stress and β-cell dysfunction in the natural history of non-syndromic Type 2 DM. Cryptic contributions of conserved residues to folding efficiency, as uncovered by rare genetic variants, define molecular links between biophysical principles and the emerging paradigm of Darwinian medicine: Biosynthesis of proinsulin at the edge of non-foldability provides a key determinant of "diabesity" as a pandemic disease of civilization.
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Affiliation(s)
| | | | | | - Michael A. Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, United States
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8
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Feng CJ, Sinitskiy A, Pande V, Tokmakoff A. Computational IR Spectroscopy of Insulin Dimer Structure and Conformational Heterogeneity. J Phys Chem B 2021; 125:4620-4633. [PMID: 33929849 DOI: 10.1021/acs.jpcb.1c00399] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We have investigated the structure and conformational dynamics of insulin dimer using a Markov state model (MSM) built from extensive unbiased atomistic molecular dynamics simulations and performed infrared spectral simulations of the insulin MSM to describe how structural variation within the dimer can be experimentally resolved. Our model reveals two significant conformations to the dimer: a dominant native state consistent with other experimental structures of the dimer and a twisted state with a structure that appears to reflect a ∼55° clockwise rotation of the native dimer interface. The twisted state primarily influences the contacts involving the C-terminus of insulin's B chain, shifting the registry of its intermolecular hydrogen bonds and reorganizing its side-chain packing. The MSM kinetics predict that these configurations exchange on a 14 μs time scale, largely passing through two Markov states with a solvated dimer interface. Computational amide I spectroscopy of site-specifically 13C18O labeled amides indicates that the native and twisted conformation can be distinguished through a series of single and dual labels involving the B24F, B25F, and B26Y residues. Additional structural heterogeneity and disorder is observed within the native and twisted states, and amide I spectroscopy can also be used to gain insight into this variation. This study will provide important interpretive tools for IR spectroscopic investigations of insulin structure and transient IR kinetics experiments studying the conformational dynamics of insulin dimer.
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Affiliation(s)
- Chi-Jui Feng
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
| | - Anton Sinitskiy
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
| | - Vijay Pande
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637, United States
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9
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Dhayalan B, Chatterjee D, Chen YS, Weiss MA. Diabetes mellitus due to toxic misfolding of proinsulin variants. Mol Metab 2021:101229. [PMID: 33823319 DOI: 10.1016/j.molmet.2021.101229] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/10/2021] [Accepted: 03/29/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Dominant mutations in the human insulin gene (INS) lead to pancreatic β-cell dysfunction and diabetes mellitus (DM) due to toxic misfolding of a mutant proinsulin. Analogous to a classical mouse model of monogenic DM ("Akita"), this syndrome highlights the susceptibility of β-cells to endoreticulum (ER) stress due to protein misfolding and aberrant aggregation. SCOPE OF REVIEW Diverse clinical mutations directly or indirectly perturb native disulfide pairing. Whereas most introduce or remove a cysteine (Cys; leading in either case to an unpaired thiol group), non-Cys-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the hormone's evolution has been constrained not only by structure-function relationships but also by the susceptibility of its single-chain precursor to impaired foldability. An intriguing hypothesis posits that INS overexpression in response to peripheral insulin resistance likewise leads to chronic ER stress and β-cell dysfunction in the natural history of nonsyndromic Type 2 DM. MAJOR CONCLUSIONS Cryptic contributions of conserved residues to folding efficiency, as uncovered by rare genetic variants, define molecular links between biophysical principles and the emerging paradigm of Darwinian medicine: Biosynthesis of proinsulin at the edge of nonfoldability provides a key determinant of "diabesity" as a pandemic disease of civilization.
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Affiliation(s)
- Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Deepak Chatterjee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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10
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Rege NK, Liu M, Dhayalan B, Chen YS, Smith NA, Rahimi L, Sun J, Guo H, Yang Y, Haataja L, Phillips NFB, Whittaker J, Smith BJ, Arvan P, Ismail-Beigi F, Weiss MA. "Register-shift" insulin analogs uncover constraints of proteotoxicity in protein evolution. J Biol Chem 2020; 295:3080-3098. [PMID: 32005662 DOI: 10.1074/jbc.ra119.011389] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/27/2020] [Indexed: 12/16/2022] Open
Abstract
Globular protein sequences encode not only functional structures (the native state) but also protein foldability, i.e. a conformational search that is both efficient and robustly minimizes misfolding. Studies of mutations associated with toxic misfolding have yielded insights into molecular determinants of protein foldability. Of particular interest are residues that are conserved yet dispensable in the native state. Here, we exploited the mutant proinsulin syndrome (a major cause of permanent neonatal-onset diabetes mellitus) to investigate whether toxic misfolding poses an evolutionary constraint. Our experiments focused on an invariant aromatic motif (PheB24-PheB25-TyrB26) with complementary roles in native self-assembly and receptor binding. A novel class of mutations provided evidence that insulin can bind to the insulin receptor (IR) in two different modes, distinguished by a "register shift" in this motif, as visualized by molecular dynamics (MD) simulations. Register-shift variants are active but defective in cellular foldability and exquisitely susceptible to fibrillation in vitro Indeed, expression of the corresponding proinsulin variant induced endoplasmic reticulum stress, a general feature of the mutant proinsulin syndrome. Although not present among vertebrate insulin and insulin-like sequences, a prototypical variant ([GlyB24]insulin) was as potent as WT insulin in a rat model of diabetes. Although in MD simulations the shifted register of receptor engagement is compatible with the structure and allosteric reorganization of the IR-signaling complex, our results suggest that this binding mode is associated with toxic misfolding and so is disallowed in evolution. The implicit threat of proteotoxicity limits sequence variation among vertebrate insulins and insulin-like growth factors.
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Affiliation(s)
- Nischay K Rege
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Ming Liu
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48105, Australia; Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, Heping District, 300052 China
| | - Balamurugan Dhayalan
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Yen-Shan Chen
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Nicholas A Smith
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Leili Rahimi
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Jinhong Sun
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48105, Australia
| | - Huan Guo
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48105, Australia
| | - Yanwu Yang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Leena Haataja
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48105, Australia
| | - Nelson F B Phillips
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Jonathan Whittaker
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Brian J Smith
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Peter Arvan
- Division of Metabolism, Endocrinology and Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48105, Australia
| | - Faramarz Ismail-Beigi
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Michael A Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202.
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11
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Liu M, Weiss MA, Arunagiri A, Yong J, Rege N, Sun J, Haataja L, Kaufman RJ, Arvan P. Biosynthesis, structure, and folding of the insulin precursor protein. Diabetes Obes Metab 2018; 20 Suppl 2:28-50. [PMID: 30230185 PMCID: PMC6463291 DOI: 10.1111/dom.13378] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/04/2018] [Accepted: 05/23/2018] [Indexed: 02/06/2023]
Abstract
Insulin synthesis in pancreatic β-cells is initiated as preproinsulin. Prevailing glucose concentrations, which oscillate pre- and postprandially, exert major dynamic variation in preproinsulin biosynthesis. Accompanying upregulated translation of the insulin precursor includes elements of the endoplasmic reticulum (ER) translocation apparatus linked to successful orientation of the signal peptide, translocation and signal peptide cleavage of preproinsulin-all of which are necessary to initiate the pathway of proper proinsulin folding. Evolutionary pressures on the primary structure of proinsulin itself have preserved the efficiency of folding ("foldability"), and remarkably, these evolutionary pressures are distinct from those protecting the ultimate biological activity of insulin. Proinsulin foldability is manifest in the ER, in which the local environment is designed to assist in the overall load of proinsulin folding and to favour its disulphide bond formation (while limiting misfolding), all of which is closely tuned to ER stress response pathways that have complex (beneficial, as well as potentially damaging) effects on pancreatic β-cells. Proinsulin misfolding may occur as a consequence of exuberant proinsulin biosynthetic load in the ER, proinsulin coding sequence mutations, or genetic predispositions that lead to an altered ER folding environment. Proinsulin misfolding is a phenotype that is very much linked to deficient insulin production and diabetes, as is seen in a variety of contexts: rodent models bearing proinsulin-misfolding mutants, human patients with Mutant INS-gene-induced Diabetes of Youth (MIDY), animal models and human patients bearing mutations in critical ER resident proteins, and, quite possibly, in more common variety type 2 diabetes.
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Affiliation(s)
- Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China 300052
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor 48105 MI USA
| | - Michael A. Weiss
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis 46202 IN USA
- Department of Biochemistry, Case-Western Reserve University, Cleveland 44016 OH USA
| | - Anoop Arunagiri
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor 48105 MI USA
| | - Jing Yong
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92307 USA
| | - Nischay Rege
- Department of Biochemistry, Case-Western Reserve University, Cleveland 44016 OH USA
| | - Jinhong Sun
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China 300052
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor 48105 MI USA
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor 48105 MI USA
| | - Randal J. Kaufman
- Degenerative Diseases Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA 92307 USA
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor 48105 MI USA
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12
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Weiss MA, Lawrence MC. A thing of beauty: Structure and function of insulin's "aromatic triplet". Diabetes Obes Metab 2018; 20 Suppl 2:51-63. [PMID: 30230175 PMCID: PMC6159917 DOI: 10.1111/dom.13402] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 05/25/2018] [Accepted: 05/31/2018] [Indexed: 12/30/2022]
Abstract
The classical crystal structure of insulin was determined in 1969 by D.C. Hodgkin et al. following a 35-year program of research. This structure depicted a hexamer remarkable for its self-assembly as a zinc-coordinated trimer of dimer. Prominent at the dimer interface was an "aromatic triplet" of conserved residues at consecutive positions in the B chain: PheB24 , PheB25 and TyrB26 . The elegance of this interface inspired the Oxford team to poetry: "A thing of beauty is a joy forever" (John Keats as quoted by Blundell, T.L., et al. Advances in Protein Chemistry 26:279-286 [1972]). Here, we revisit this aromatic triplet in light of recent advances in the structural biology of insulin bound as a monomer to fragments of the insulin receptor. Such co-crystal structures have defined how these side chains pack at the primary hormone-binding surface of the receptor ectodomain. On receptor binding, the B-chain β-strand (residues B24-B28) containing the aromatic triplet detaches from the α-helical core of the hormone. Whereas TyrB26 lies at the periphery of the receptor interface and may functionally be replaced by a diverse set of substitutions, PheB24 and PheB25 engage invariant elements of receptor domains L1 and αCT. These critical contacts were anticipated by the discovery of diabetes-associated mutations at these positions by Donald Steiner et al. at the University of Chicago. Conservation of PheB24 , PheB25 and TyrB26 among vertebrate insulins reflects the striking confluence of structure-based evolutionary constraints: foldability, protective self-assembly and hormonal activity.
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Affiliation(s)
- Michael A. Weiss
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202 USA
| | - Michael C. Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, AUSTRALIA
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, AUSTRALIA
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13
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Efimov SV, Zgadzay YO, Tarasova NB, Klochkov VV. Evidence of oligomerization of bovine insulin in solution given by NMR. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 47:881-889. [PMID: 29858914 DOI: 10.1007/s00249-018-1310-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2018] [Revised: 04/14/2018] [Accepted: 05/16/2018] [Indexed: 01/21/2023]
Abstract
The protein hormone insulin exists in several forms in nature, and a large number of modified sequences are used in pharmacy. They differ by physicochemical properties and efficiency of biological action. Pancreatic bovine insulin was studied in an acidic solution by nuclear magnetic resonance spectroscopy. [Formula: see text]H and [Formula: see text]C NMR signal assignment of backbone and side chains was made by analysis of a set of 2D spectra obtained on a sample with natural isotope abundance. The presence of certain secondary structure elements was revealed on a qualitative level based on nuclear Overhauser effect spectroscopy, which are similar to those observed in the crystal structure. The C-terminus of the B-chain possessed a remarkable flexibility. The molecule was shown to exist in exchange with oligomers based on its self-diffusion coefficient and correlation time measurements performed at different concentrations. Certain signals in the NOESY and HSQC spectra are consistent with the presence of minor conformers; this is an obstacle in simulating the molecular structure under the conditions used in the experiment.
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Affiliation(s)
- S V Efimov
- Laboratory of NMR spectroscopy, Institute of Physics, Kazan Federal University, 18 Kremlevskaya St., Kazan, 420008, Russia.
| | - Yu O Zgadzay
- Laboratory of NMR spectroscopy, Institute of Physics, Kazan Federal University, 18 Kremlevskaya St., Kazan, 420008, Russia
| | - N B Tarasova
- Laboratory of Molecular Biology, Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2 Lobachevskiy St., Kazan, 420111, Russia
| | - V V Klochkov
- Laboratory of NMR spectroscopy, Institute of Physics, Kazan Federal University, 18 Kremlevskaya St., Kazan, 420008, Russia
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Glidden MD, Yang Y, Smith NA, Phillips NB, Carr K, Wickramasinghe NP, Ismail-Beigi F, Lawrence MC, Smith BJ, Weiss MA. Solution structure of an ultra-stable single-chain insulin analog connects protein dynamics to a novel mechanism of receptor binding. J Biol Chem 2018; 293:69-88. [PMID: 29114034 PMCID: PMC5766920 DOI: 10.1074/jbc.m117.808667] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/12/2017] [Indexed: 12/11/2022] Open
Abstract
Domain-minimized insulin receptors (IRs) have enabled crystallographic analysis of insulin-bound "micro-receptors." In such structures, the C-terminal segment of the insulin B chain inserts between conserved IR domains, unmasking an invariant receptor-binding surface that spans both insulin A and B chains. This "open" conformation not only rationalizes the inactivity of single-chain insulin (SCI) analogs (in which the A and B chains are directly linked), but also suggests that connecting (C) domains of sufficient length will bind the IR. Here, we report the high-resolution solution structure and dynamics of such an active SCI. The hormone's closed-to-open transition is foreshadowed by segmental flexibility in the native state as probed by heteronuclear NMR spectroscopy and multiple conformer simulations of crystallographic protomers as described in the companion article. We propose a model of the SCI's IR-bound state based on molecular-dynamics simulations of a micro-receptor complex. In this model, a loop defined by the SCI's B and C domains encircles the C-terminal segment of the IR α-subunit. This binding mode predicts a conformational transition between an ultra-stable closed state (in the free hormone) and an active open state (on receptor binding). Optimization of this switch within an ultra-stable SCI promises to circumvent insulin's complex global cold chain. The analog's biphasic activity, which serendipitously resembles current premixed formulations of soluble insulin and microcrystalline suspension, may be of particular utility in the developing world.
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Affiliation(s)
- Michael D Glidden
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106
| | - Yanwu Yang
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Nicholas A Smith
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Nelson B Phillips
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Kelley Carr
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | | | - Faramarz Ismail-Beigi
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106; Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Michael C Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Brian J Smith
- La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Michael A Weiss
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106; Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106.
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Glidden MD, Aldabbagh K, Phillips NB, Carr K, Chen YS, Whittaker J, Phillips M, Wickramasinghe NP, Rege N, Swain M, Peng Y, Yang Y, Lawrence MC, Yee VC, Ismail-Beigi F, Weiss MA. An ultra-stable single-chain insulin analog resists thermal inactivation and exhibits biological signaling duration equivalent to the native protein. J Biol Chem 2017; 293:47-68. [PMID: 29114035 DOI: 10.1074/jbc.m117.808626] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/12/2017] [Indexed: 12/12/2022] Open
Abstract
Thermal degradation of insulin complicates its delivery and use. Previous efforts to engineer ultra-stable analogs were confounded by prolonged cellular signaling in vivo, of unclear safety and complicating mealtime therapy. We therefore sought an ultra-stable analog whose potency and duration of action on intravenous bolus injection in diabetic rats are indistinguishable from wild-type (WT) insulin. Here, we describe the structure, function, and stability of such an analog, a 57-residue single-chain insulin (SCI) with multiple acidic substitutions. Cell-based studies revealed native-like signaling properties with negligible mitogenic activity. Its crystal structure, determined as a novel zinc-free hexamer at 2.8 Å, revealed a native insulin fold with incomplete or absent electron density in the C domain; complementary NMR studies are described in the accompanying article. The stability of the analog (ΔGU 5.0(±0.1) kcal/mol at 25 °C) was greater than that of WT insulin (3.3(±0.1) kcal/mol). On gentle agitation, the SCI retained full activity for >140 days at 45 °C and >48 h at 75 °C. These findings indicate that marked resistance to thermal inactivation in vitro is compatible with native duration of activity in vivo Further, whereas WT insulin forms large and heterogeneous aggregates above the standard 0.6 mm pharmaceutical strength, perturbing the pharmacokinetic properties of concentrated formulations, dynamic light scattering, and size-exclusion chromatography revealed only limited SCI self-assembly and aggregation in the concentration range 1-7 mm Such a combination of favorable biophysical and biological properties suggests that SCIs could provide a global therapeutic platform without a cold chain.
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Affiliation(s)
- Michael D Glidden
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106
| | - Khadijah Aldabbagh
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Nelson B Phillips
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Kelley Carr
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Yen-Shan Chen
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Jonathan Whittaker
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Manijeh Phillips
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | | | - Nischay Rege
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Mamuni Swain
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Yi Peng
- Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106
| | - Yanwu Yang
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Michael C Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Vivien C Yee
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Faramarz Ismail-Beigi
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106; Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | - Michael A Weiss
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106; Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106; Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106.
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El Hage K, Pandyarajan V, Phillips NB, Smith BJ, Menting JG, Whittaker J, Lawrence MC, Meuwly M, Weiss MA. Extending Halogen-based Medicinal Chemistry to Proteins: IODO-INSULIN AS A CASE STUDY. J Biol Chem 2016; 291:27023-27041. [PMID: 27875310 PMCID: PMC5207135 DOI: 10.1074/jbc.m116.761015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 10/31/2016] [Indexed: 12/13/2022] Open
Abstract
Insulin, a protein critical for metabolic homeostasis, provides a classical model for protein design with application to human health. Recent efforts to improve its pharmaceutical formulation demonstrated that iodination of a conserved tyrosine (TyrB26) enhances key properties of a rapid-acting clinical analog. Moreover, the broad utility of halogens in medicinal chemistry has motivated the use of hybrid quantum- and molecular-mechanical methods to study proteins. Here, we (i) undertook quantitative atomistic simulations of 3-[iodo-TyrB26]insulin to predict its structural features, and (ii) tested these predictions by X-ray crystallography. Using an electrostatic model of the modified aromatic ring based on quantum chemistry, the calculations suggested that the analog, as a dimer and hexamer, exhibits subtle differences in aromatic-aromatic interactions at the dimer interface. Aromatic rings (TyrB16, PheB24, PheB25, 3-I-TyrB26, and their symmetry-related mates) at this interface adjust to enable packing of the hydrophobic iodine atoms within the core of each monomer. Strikingly, these features were observed in the crystal structure of a 3-[iodo-TyrB26]insulin analog (determined as an R6 zinc hexamer). Given that residues B24-B30 detach from the core on receptor binding, the environment of 3-I-TyrB26 in a receptor complex must differ from that in the free hormone. Based on the recent structure of a "micro-receptor" complex, we predict that 3-I-TyrB26 engages the receptor via directional halogen bonding and halogen-directed hydrogen bonding as follows: favorable electrostatic interactions exploiting, respectively, the halogen's electron-deficient σ-hole and electronegative equatorial band. Inspired by quantum chemistry and molecular dynamics, such "halogen engineering" promises to extend principles of medicinal chemistry to proteins.
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Affiliation(s)
- Krystel El Hage
- From the Department of Chemistry, University of Basel, Klingelbergstrasse 80 CH-4056 Basel, Switzerland
| | | | | | - Brian J Smith
- the La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - John G Menting
- the The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia, and
| | | | - Michael C Lawrence
- the The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3052, Australia, and
- the Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Markus Meuwly
- From the Department of Chemistry, University of Basel, Klingelbergstrasse 80 CH-4056 Basel, Switzerland,
| | - Michael A Weiss
- the Departments of Biochemistry,
- Medicine, and
- Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106
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Mills BJ, Laurence Chadwick JS. Effects of localized interactions and surface properties on stability of protein-based therapeutics. ACTA ACUST UNITED AC 2016; 70:609-624. [PMID: 27861887 DOI: 10.1111/jphp.12658] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 09/04/2016] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Protein-based therapeutics garner significant attention because of exquisite specificity and limited side effects and are now being used to accomplish targeted delivery of small-molecule drugs. This review identifies and highlights individual chemical attributes and categorizes how site-specific changes affect protein stability based on published high-resolution molecular analyses. KEY FINDINGS Because it is challenging to determine the mechanisms by which the stability of large, complex molecules is altered and data are sparse, smaller, therapeutic proteins (insulin, erythropoietin, interferons) are examined alongside antibody data. Integrating this large pool of information with the limited available studies on antibodies reveals common mechanisms by which specific alterations affect protein structure and stability. SUMMARY Physical and chemical stability of therapeutic proteins and antibody drug conjugates (ADCs) is of critical importance because insufficient stability prevents molecules from making it to market. Individual moieties on/near the surface of proteins have substantial influence on structure and stability. Seemingly small, superficial modification may have far-reaching consequences on structure, conformational dynamics, and solubility of the protein, and hence physical stability of the molecule. Chemical modifications, whether spontaneous (e.g. oxidation, deamidation) or intentional, as with ADCs, may adversely impact stability by disrupting local surface properties or higher order protein structure.
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Affiliation(s)
- Brittney J Mills
- Department of Chemistry, The University of Kansas, Lawrence, KS, USA
| | - Jennifer S Laurence Chadwick
- Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS, USA.,BioAnalytix Inc., Cambridge, MA, USA
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18
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Zhang XX, Jones KC, Fitzpatrick A, Peng CS, Feng CJ, Baiz CR, Tokmakoff A. Studying Protein-Protein Binding through T-Jump Induced Dissociation: Transient 2D IR Spectroscopy of Insulin Dimer. J Phys Chem B 2016; 120:5134-45. [PMID: 27203447 DOI: 10.1021/acs.jpcb.6b03246] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Insulin homodimer associates through the coupled folding and binding of two partially disordered monomers. We aim to understand this dynamics by observing insulin dimer dissociation initiated with a nanosecond temperature jump using transient two-dimensional infrared spectroscopy (2D IR) of amide I vibrations. With the help of equilibrium FTIR and 2D IR spectra, and through a systematic study of the dependence of dissociation kinetics on temperature and insulin concentration, we are able to decompose and analyze the spectral evolution associated with different secondary structures. We find that the dissociation under all conditions is characterized by two processes whose influence on the kinetics varies with temperature: the unfolding of the β sheet at the dimer interface observed as exponential kinetics between 250 and 1000 μs and nonexponential kinetics between 5 and 150 μs that we attribute to monomer disordering. Microscopic reversibility arguments lead us to conclude that dimer association requires significant conformational changes within the monomer in concert with the folding of the interfacial β sheet. While our data indicates a more complex kinetics, we apply a two-state model to the β-sheet unfolding kinetics to extract thermodynamic parameters and kinetic rate constants. The association rate constant, ka (23 °C) = 8.8 × 10(5) M(-1) s(-1) (pH 0, 20% EtOD), is approximately 3 orders of magnitude slower than the calculated diffusion limited association rate, which is explained by the significant destabilizing effect of ethanol on the dimer state and the highly positive charge of the monomers at this pH.
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Affiliation(s)
- Xin-Xing Zhang
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Kevin C Jones
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Ann Fitzpatrick
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Chunte Sam Peng
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Chi-Jui Feng
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Carlos R Baiz
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - Andrei Tokmakoff
- Department of Chemistry, Institute for Biophysical Dynamics, and the James Franck Institute, The University of Chicago , Chicago, Illinois 60637, United States
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19
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Hjorth CF, Norrman M, Wahlund PO, Benie AJ, Petersen BO, Jessen CM, Pedersen TÅ, Vestergaard K, Steensgaard DB, Pedersen JS, Naver H, Hubálek F, Poulsen C, Otzen D. Structure, Aggregation, and Activity of a Covalent Insulin Dimer Formed During Storage of Neutral Formulation of Human Insulin. J Pharm Sci 2016; 105:1376-86. [DOI: 10.1016/j.xphs.2016.01.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/11/2015] [Accepted: 01/06/2016] [Indexed: 10/22/2022]
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20
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Theoretical investigation on insulin dimer-β-cyclodextrin interactions using docking and molecular dynamics simulation. J INCL PHENOM MACRO 2015. [DOI: 10.1007/s10847-015-0576-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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21
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Li Z, Zhang Y, Lu D, Liu Z. Uniform mPEG- b-PMETAC enables pH-responsive delivery of insulin. J Appl Polym Sci 2015. [DOI: 10.1002/app.42596] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Zongjun Li
- Key Lab for Industrial Biocatalysis; Ministry of Education; Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Yifei Zhang
- Key Lab for Industrial Biocatalysis; Ministry of Education; Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Diannan Lu
- Key Lab for Industrial Biocatalysis; Ministry of Education; Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
| | - Zheng Liu
- Key Lab for Industrial Biocatalysis; Ministry of Education; Department of Chemical Engineering; Tsinghua University; Beijing 100084 China
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22
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Rawat S, Gupta P, Kumar A, Garg P, Suri CR, Sahoo DK. Molecular Mechanism of Poly(vinyl alcohol) Mediated Prevention of Aggregation and Stabilization of Insulin in Nanoparticles. Mol Pharm 2015; 12:1018-30. [DOI: 10.1021/mp5003653] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Sanjay Rawat
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
| | - Pawan Gupta
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, Mohali 160062, India
| | - Anil Kumar
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
| | - Prabha Garg
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research, Sector 67, Mohali 160062, India
| | - C. Raman Suri
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
| | - Debendra K. Sahoo
- CSIR−Institute of Microbial Technology, Sector 39-A, Chandigarh 160036, India
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Avital-Shmilovici M, Whittaker J, Weiss MA, Kent SBH. Deciphering a molecular mechanism of neonatal diabetes mellitus by the chemical synthesis of a protein diastereomer, [D-AlaB8]human proinsulin. J Biol Chem 2014; 289:23683-92. [PMID: 25002580 DOI: 10.1074/jbc.m114.572040] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Misfolding of proinsulin variants in the pancreatic β-cell, a monogenic cause of permanent neonatal-onset diabetes mellitus, provides a model for a disease of protein toxicity. A hot spot for such clinical mutations is found at position B8, conserved as glycine within the vertebrate insulin superfamily. We set out to investigate the molecular basis of the aberrant properties of a proinsulin clinical mutant in which residue Gly(B8) is replaced by Ser(B8). Modular total chemical synthesis was used to prepare the wild-type [Gly(B8)]proinsulin molecule and three analogs: [D-Ala(B8)]proinsulin, [L-Ala(B8)]proinsulin, and the clinical mutant [L-Ser(B8)]proinsulin. The protein diastereomer [D-Ala(B8)]proinsulin produced higher folding yields at all pH values compared with the wild-type proinsulin and the other two analogs, but showed only very weak binding to the insulin receptor. The clinical mutant [L-Ser(B8)]proinsulin impaired folding at pH 7.5 even in the presence of protein-disulfide isomerase. Surprisingly, although [L-Ser(B8)]proinsulin did not fold well under the physiological conditions investigated, once folded the [L-Ser(B8)]proinsulin protein molecule bound to the insulin receptor more effectively than wild-type proinsulin. Such paradoxical gain of function (not pertinent in vivo due to impaired secretion of the mutant insulin) presumably reflects induced fit in the native mechanism of hormone-receptor engagement. This work provides insight into the molecular mechanism of a clinical mutation in the insulin gene associated with diabetes mellitus. These results dramatically illustrate the power of total protein synthesis, as enabled by modern chemical ligation methods, for the investigation of protein folding and misfolding.
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Affiliation(s)
- Michal Avital-Shmilovici
- From the Departments of Chemistry, and Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 and
| | | | - Michael A Weiss
- the Departments of Biochemistry and Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106
| | - Stephen B H Kent
- From the Departments of Chemistry, and Biochemistry and Molecular Biology, Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 and
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24
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Lei C, Noonan O, Jambhrunkar S, Qian K, Xu C, Zhang J, Nouwens A, Yu C. Sensitive detection of human insulin using a designed combined pore approach. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:2413-8. [PMID: 24599559 DOI: 10.1002/smll.201303748] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/18/2014] [Indexed: 05/26/2023]
Abstract
A unique combined pore approach to the sensitive detection of human insulin is developed. Through a systematic study to understand the impact of pore size and surface chemistry of nanoporous materials on their enrichment and purification performance, the advantages of selected porous materials are integrated to enhance detection sensitivity in a unified two-step process. In the first purification step, a rationally designed large pore material (ca. 100 nm in diameter) is chosen to repel the interferences from nontarget molecules. In the second enrichment step, a hydrophobically modified mesoporous material with a pore size of 5 nm is selected to enrich insulin molecules. A low detection limit of 0.05 ng mL(-1) in artificial urine is achieved by this advanced approach, similar to most antibody-based analysis protocols. This designer approach is efficient and low cost, and thus has great potential in the sensitive detection of biomolecules in complex biological systems.
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Affiliation(s)
- Chang Lei
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD, 4072, Australia
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25
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Teska BM, Alarcón J, Pettis RJ, Randolph TW, Carpenter JF. Effects of phenol and meta-cresol depletion on insulin analog stability at physiological temperature. J Pharm Sci 2014; 103:2255-67. [PMID: 24909933 DOI: 10.1002/jps.24039] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 05/13/2014] [Accepted: 05/16/2014] [Indexed: 11/11/2022]
Abstract
The stability of three commercial "fast-acting" insulin analogs, insulin lispro, insulin aspart, and insulin glulisine, was studied at various concentrations of phenolic preservatives (phenol and/or meta-cresol) during 9 days of incubation at 37 °C. The analysis by both size-exclusion and reversed-phase chromatography showed degradation of lispro and aspart that was inversely dependent on the concentration of phenolic preservatives. Insulin glulisine was much more stable than the other analogs and showed minimal degradation even in the absence of phenolic preservatives. With sedimentation velocity ultracentrifugation, we determined the preservatives' effect on the insulins' self-assembly. When depleted of preservatives, insulin glulisine dissociates from higher molecular weight species into a number of intermediate molecular weight species, in between monomer and hexamer, whereas insulin aspart and insulin lispro dissociate into monomers and dimers. Decreased stability of insulin lispro and insulin aspart seems to be because of the extent of dissociation when depleted of preservative. Insulin glulisine's dissociation to intermediate molecular weight species appears to help minimize its degradation during incubation at 37 °C.
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Affiliation(s)
- Brandon M Teska
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045
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26
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Kosinová L, Veverka V, Novotná P, Collinsová M, Urbanová M, Moody NR, Turkenburg JP, Jiráček J, Brzozowski AM, Žáková L. Insight into the structural and biological relevance of the T/R transition of the N-terminus of the B-chain in human insulin. Biochemistry 2014; 53:3392-402. [PMID: 24819248 PMCID: PMC4047818 DOI: 10.1021/bi500073z] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
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The N-terminus of the B-chain of
insulin may adopt two alternative
conformations designated as the T- and R-states. Despite the recent
structural insight into insulin–insulin receptor (IR) complexes,
the physiological relevance of the T/R transition is still unclear.
Hence, this study focused on the rational design, synthesis, and characterization
of human insulin analogues structurally locked in expected R- or T-states.
Sites B3, B5, and B8, capable of affecting the conformation of the
N-terminus of the B-chain, were subjects of rational substitutions
with amino acids with specific allowed and disallowed dihedral φ
and ψ main-chain angles. α-Aminoisobutyric acid was systematically
incorporated into positions B3, B5, and B8 for stabilization of the
R-state, and N-methylalanine and d-proline
amino acids were introduced at position B8 for stabilization of the
T-state. IR affinities of the analogues were compared and correlated
with their T/R transition ability and analyzed against their crystal
and nuclear magnetic resonance structures. Our data revealed that
(i) the T-like state is indeed important for the folding efficiency
of (pro)insulin, (ii) the R-state is most probably incompatible with
an active form of insulin, (iii) the R-state cannot be induced or
stabilized by a single substitution at a specific site, and (iv) the
B1–B8 segment is capable of folding into a variety of low-affinity
T-like states. Therefore, we conclude that the active conformation
of the N-terminus of the B-chain must be different from the “classical”
T-state and that a substantial flexibility of the B1–B8 segment,
where GlyB8 plays a key role, is a crucial prerequisite for an efficient
insulin–IR interaction.
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Affiliation(s)
- Lucie Kosinová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
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27
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Oneda H, Inouye K. Detection of Antigen-antibody Reaction Using a Fluorescent Probe and Its Application to Homogeneous Competitive-type Immunoassay for Insulin. Biosci Biotechnol Biochem 2014; 68:2190-2. [PMID: 15502368 DOI: 10.1271/bbb.68.2190] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The interaction of bovine insulin with anti-human insulin antibody (mAb) was examined using a fluorescent probe. The fluorescence intensity of fluoresceinthiocarbamyl (FTC)-insulin was increased by adding mAb, and the increase was saturated at 53% at a molar ratio of FTC-insulin to mAb of 2.0. Based on the change in fluorescence intensity, a standard curve of the homogeneous competitive-type immunoassay was constructed, and the detection range of insulin was found to be 50-400 nM.
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Affiliation(s)
- Hiroshi Oneda
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Sankyo-ku, Kyoto 606-8502, Japan
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28
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Chinisaz M, Larijani B, Ebrahim-Habibi A. A molecular modeling study on full-length insulin: insight into initial events of amyloid formation. Struct Chem 2014. [DOI: 10.1007/s11224-014-0395-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Structural meta-analysis of regular human insulin in pharmaceutical formulations. Eur J Pharm Biopharm 2013; 85:1112-21. [PMID: 23692694 DOI: 10.1016/j.ejpb.2013.05.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/11/2013] [Accepted: 05/06/2013] [Indexed: 01/11/2023]
Abstract
We have studied regular acting, wild-type human insulin at potency of 100 U/mL from four different pharmaceutical products directly from their final finished formulation by the combined use of mass spectrometry (MS), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR), and single-crystal protein crystallography (PX). All products showed similar oligomeric assembly in solution as judged by DLS and SAXS measurements. The NMR spectra were compatible with well folded proteins, showing close conformational identity for the human insulin in the four products. Crystallographic assays conducted with the final formulated products resulted in all insulin crystals belonging to the R3 space group with two a dimer in the asymmetric unit, both with the B-chain in the T configuration. Meta-analysis of the 24 crystal structures solved from the four distinct insulin products revealed close similarity between them regardless of variables such as biological origin, product batch, country origin of the product, and analytical approach, revealing a low conformational variability for the converging insulin structural ensemble. We propose the use of MS, SAXS, NMR fingerprint, and PX as a precise chemical and structural proof of folding identity of regular insulin in the final, formulated product.
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30
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Diabetes mellitus due to the toxic misfolding of proinsulin variants. FEBS Lett 2013; 587:1942-50. [PMID: 23669362 DOI: 10.1016/j.febslet.2013.04.044] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 04/29/2013] [Accepted: 04/30/2013] [Indexed: 02/06/2023]
Abstract
Dominant mutations in the human insulin gene can lead to pancreatic β-cell dysfunction and diabetes mellitus due to toxic folding of a mutant proinsulin. Analogous to a classical mouse model (the Akita mouse), this monogenic syndrome highlights the susceptibility of human β-cells to endoreticular stress due to protein misfolding and aberrant aggregation. The clinical mutations directly or indirectly perturb native disulfide pairing. Whereas the majority of mutations introduce or remove a cysteine (leading in either case to an unpaired residue), non-cysteine-related mutations identify key determinants of folding efficiency. Studies of such mutations suggest that the evolution of insulin has been constrained not only by its structure and function, but also by the susceptibility of its single-chain precursor to impaired foldability.
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31
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Palmieri LC, Fávero-Retto MP, Lourenço D, Lima LMT. A T3R3 hexamer of the human insulin variant B28Asp. Biophys Chem 2013; 173-174:1-7. [DOI: 10.1016/j.bpc.2013.01.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2012] [Revised: 01/01/2013] [Accepted: 01/04/2013] [Indexed: 10/27/2022]
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32
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Bellia F, Pietropaolo A, Grasso G. Formation of insulin fragments by insulin-degrading enzyme: the role of zinc(II) and cystine bridges. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:135-140. [PMID: 23378084 DOI: 10.1002/jms.3060] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 06/15/2012] [Accepted: 07/02/2012] [Indexed: 06/01/2023]
Abstract
Insulin is the hormone mainly involved in widespread diseases such as diabetes mellitus. It is widely recognized that metal ions such as zinc(II) as well as insulin degradation and insulin fragments are inexplicably linked to the hormone action. Insulin-degrading enzyme (IDE) has been identified as the main factor of insulin degradation, but it is still unknown the exact way and location at which IDE action toward insulin occurs and how metal ions can modulate this interaction. Interestingly, some insulin fragments have different biological activity from the intact hormone, and it is not clear how they can be generated from insulin. In this work, the role of zinc(II) and cystine bridges in the degradation of insulin by IDE are investigated by high-performance liquid chromatography-mass spectrometry (HPLC-MS), and the experimental conditions at which peculiar insulin fragments having biological activity are formed by the action of IDE are found and discussed. Docking simulations of IDE/insulin A and B chains are in good accordance with the insulin fragments detected by HPLC-MS.
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Affiliation(s)
- Francesco Bellia
- Istituto Biostrutture e Bioimmagini, CNR, Viale A. Doria 6, Catania, Italy
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33
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Steensgaard DB, Schluckebier G, Strauss HM, Norrman M, Thomsen JK, Friderichsen AV, Havelund S, Jonassen I. Ligand-controlled assembly of hexamers, dihexamers, and linear multihexamer structures by the engineered acylated insulin degludec. Biochemistry 2013; 52:295-309. [PMID: 23256685 DOI: 10.1021/bi3008609] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Insulin degludec, an engineered acylated insulin, was recently reported to form a soluble depot after subcutaneous injection with a subsequent slow release of insulin and an ultralong glucose-lowering effect in excess of 40 h in humans. We describe the structure, ligand binding properties, and self-assemblies of insulin degludec using orthogonal structural methods. The protein fold adopted by insulin degludec is very similar to that of human insulin. Hexamers in the R(6) state similar to those of human insulin are observed for insulin degludec in the presence of zinc and resorcinol. However, under conditions comparable to the pharmaceutical formulation comprising zinc and phenol, insulin degludec forms finite dihexamers that are composed of hexamers in the T(3)R(3) state that interact to form an R(3)T(3)-T(3)R(3) structure. When the phenolic ligand is depleted and the solvent condition thereby mimics that of the injection site, the quaternary structure changes from dihexamers to a supramolecular structure composed of linear arrays of hundreds of hexamers in the T(6) state and an average molar mass, M(0), of 59.7 × 10(3) kg/mol. This novel concept of self-assemblies of insulin controlled by zinc and phenol provides the basis for the slow action profile of insulin degludec. To the best of our knowledge, this report for the first time describes a tight linkage between quaternary insulin structures of hexamers, dihexamers, and multihexamers and their allosteric state and its origin in the inherent propensity of the insulin hexamer for allosteric half-site reactivity.
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Affiliation(s)
- Dorte B Steensgaard
- Diabetes Protein Engineering, Novo Nordisk A/S , Novo Nordisk Park, 2760 Maaloev, Denmark.
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34
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Phillips NB, Whittaker J, Ismail-Beigi F, Weiss MA. Insulin fibrillation and protein design: topological resistance of single-chain analogs to thermal degradation with application to a pump reservoir. J Diabetes Sci Technol 2012; 6:277-88. [PMID: 22538136 PMCID: PMC3380768 DOI: 10.1177/193229681200600210] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Insulin is susceptible to thermal fibrillation, a misfolding process that leads to nonnative cross-β assembly analogous to pathological amyloid deposition. Pharmaceutical formulations are ordinarily protected from such degradation by sequestration of the susceptible monomer within native protein assemblies. With respect to the safety and efficacy of insulin pumps, however, this strategy imposes an intrinsic trade-off between pharmacokinetic goals (rapid absorption and clearance) and the requisite physical properties of a formulation (prolonged shelf life and stability within the reservoir). Available rapid-acting formulations are suboptimal in both respects; susceptibility to fibrillation is exacerbated even as absorption is delayed relative to the ideal specifications of a closed-loop system. To circumvent this molecular trade-off, we exploited structural models of insulin fibrils and amyloidogenic intermediates to define an alternative protective mechanism. Single-chain insulin (SCI) analogs were shown to be refractory to thermal fibrillation with maintenance of biological activity for more than 3 months under conditions that promote the rapid fibrillation and inactivation of insulin. The essential idea exploits an intrinsic incompatibility between SCI topology and the geometry of cross-β assembly. A peptide tether was thus interposed between the A- and B-chains whose length was (a) sufficiently long to provide the "play" needed for induced fit of the hormone on receptor binding and yet (b) sufficiently short to impose a topological barrier to fibrillation. Our findings suggest that ultrastable monomeric SCI analogs may be formulated without protective self-assembly and so permit simultaneous optimization of pharmacokinetics and reservoir life.
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Affiliation(s)
- Nelson B. Phillips
- Department of Biochemistry, Case Western Reserve University School of MedicineCleveland, Ohio
| | - Jonathan Whittaker
- Department of Biochemistry, Case Western Reserve University School of MedicineCleveland, Ohio
| | - Faramarz Ismail-Beigi
- Department of Medicine, Case Western Reserve University School of MedicineCleveland, Ohio
| | - Michael A. Weiss
- Department of Biochemistry, Case Western Reserve University School of MedicineCleveland, Ohio
- Department of Medicine, Case Western Reserve University School of MedicineCleveland, Ohio
- Biomedical Engineering, Case Western Reserve University School of MedicineCleveland, Ohio
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35
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Vinther TN, Norrman M, Strauss HM, Huus K, Schlein M, Pedersen TÅ, Kjeldsen T, Jensen KJ, Hubálek F. Novel covalently linked insulin dimer engineered to investigate the function of insulin dimerization. PLoS One 2012; 7:e30882. [PMID: 22363506 PMCID: PMC3281904 DOI: 10.1371/journal.pone.0030882] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 12/23/2011] [Indexed: 11/18/2022] Open
Abstract
An ingenious system evolved to facilitate insulin binding to the insulin receptor as a monomer and at the same time ensure sufficient stability of insulin during storage. Insulin dimer is the cornerstone of this system. Insulin dimer is relatively weak, which ensures dissociation into monomers in the circulation, and it is stabilized by hexamer formation in the presence of zinc ions during storage in the pancreatic β-cell. Due to the transient nature of insulin dimer, direct investigation of this important form is inherently difficult. To address the relationship between insulin oligomerization and insulin stability and function, we engineered a covalently linked insulin dimer in which two monomers were linked by a disulfide bond. The structure of this covalent dimer was identical to the self-association dimer of human insulin. Importantly, this covalent dimer was capable of further oligomerization to form the structural equivalent of the classical hexamer. The covalently linked dimer neither bound to the insulin receptor, nor induced a metabolic response in vitro. However, it was extremely thermodynamically stable and did not form amyloid fibrils when subjected to mechanical stress, underlining the importance of oligomerization for insulin stability.
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Affiliation(s)
- Tine N. Vinther
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
- Faculty of Life Sciences, IGM, University of Copenhagen, Frederiksberg, Denmark
| | - Mathias Norrman
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Holger M. Strauss
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Kasper Huus
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Morten Schlein
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Thomas Å. Pedersen
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Thomas Kjeldsen
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
| | - Knud J. Jensen
- Faculty of Life Sciences, IGM, University of Copenhagen, Frederiksberg, Denmark
| | - František Hubálek
- Diabetes Research Unit, Novo Nordisk A/S, Novo Nordisk Park, Måløv, Denmark
- * E-mail:
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36
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Berenson DF, Weiss AR, Wan ZL, Weiss MA. Insulin analogs for the treatment of diabetes mellitus: therapeutic applications of protein engineering. Ann N Y Acad Sci 2011; 1243:E40-E54. [PMID: 22641195 PMCID: PMC3360579 DOI: 10.1111/j.1749-6632.2012.06468.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The engineering of insulin analogs represents a triumph of structure-based protein design. A framework has been provided by structures of insulin hexamers. Containing a zinc-coordinated trimer of dimers, such structures represent a storage form of the active insulin monomer. Initial studies focused on destabilization of subunit interfaces. Because disassembly facilitates capillary absorption, such targeted destabilization enabled development of rapid-acting insulin analogs. Converse efforts were undertaken to stabilize the insulin hexamer and promote higher-order self-assembly within the subcutaneous depot toward the goal of enhanced basal glycemic control with reduced risk of hypoglycemia. Current products either operate through isoelectric precipitation (insulin glargine, the active component of Lantus(®); Sanofi-Aventis) or employ an albumin-binding acyl tether (insulin detemir, the active component of Levemir(®); Novo-Nordisk). To further improve pharmacokinetic properties, modified approaches are presently under investigation. Novel strategies have recently been proposed based on subcutaneous supramolecular assembly coupled to (a) large-scale allosteric reorganization of the insulin hexamer (the TR transition), (b) pH-dependent binding of zinc ions to engineered His-X(3)-His sites at hexamer surfaces, or (c) the long-range vision of glucose-responsive polymers for regulated hormone release. Such designs share with wild-type insulin and current insulin products a susceptibility to degradation above room temperature, and so their delivery, storage, and use require the infrastructure of an affluent society. Given the global dimensions of the therapeutic supply chain, we envisage that concurrent engineering of ultra-stable protein analog formulations would benefit underprivileged patients in the developing world.
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Affiliation(s)
- Daniel F. Berenson
- Department of Molecular Biophysics and Biochemistry Yale University. New Haven, CT
| | - Allison R. Weiss
- National Institute of Diabetes, Digestive and Kidney Diseases National Institutes of Health, Bethesda, MD
| | - Zhu-li Wan
- Departments of Biochemistry, Biomedical Engineering and Medicine, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Michael A. Weiss
- Departments of Biochemistry, Biomedical Engineering and Medicine, Case Western Reserve University School of Medicine, Cleveland, OH
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37
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Lim SI, Jang MH, Kim DJ, Bae SM, Kwon SC. Cobalt(III)-induced hexamerization of PEGylated insulin. Int J Biol Macromol 2011; 49:832-7. [DOI: 10.1016/j.ijbiomac.2011.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 07/26/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
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38
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Borowicz P, Bocian W, Sitkowski J, Bednarek E, Mikiewicz-Syguła D, Błażej-Sosnowska S, Bogiel M, Rusek D, Kurzynoga D, Kozerski L. Novel recombinant insulin analogue with flexible C-terminus in B chain. NMR structure of biosynthetic engineered A22G-B31K-B32R human insulin monomer in water/acetonitrile solution. Int J Biol Macromol 2011; 49:548-54. [PMID: 21704065 DOI: 10.1016/j.ijbiomac.2011.06.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 06/08/2011] [Accepted: 06/08/2011] [Indexed: 11/16/2022]
Abstract
A tertiary structure of recombinant A22(G)-B31(K)-B32(R)-human insulin monomer (insulin GKR) has been characterized by (1)H, (13)C NMR at natural isotopic abundance using NOESY, TOCSY, (1)H/(13)C-GHSQC, and (1)H/(13)C-GHSQC-TOCSY spectra. Translational diffusion studies indicate the monomer structure in water/acetonitrile (65/35vol.%). CSI analysis confirms existence of secondary structure motifs present in human insulin standard (HIS). Both techniques allow to establish that in this solvent recombinant insulin GKR exists as a monomer. Starting from structures calculated by the program CYANA, two different refinement protocols used molecular dynamics simulated annealing with the program AMBER; in vacuum (AMBER_VC), and including a generalized Born solvent model (AMBER_GB). From these calculations an ensemble of 20 structures of lowest energy was chosen which represents the tertiary structure of studied insulin. Here we present novel insulin with added A22(G) amino acid which interacts with β-turn environment resulting in high flexibility of B chain C-terminus.
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Affiliation(s)
- Piotr Borowicz
- Institute of Biotechnology and Antibiotics, Warsaw, Poland
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39
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Antolíková E, Žáková L, Turkenburg JP, Watson CJ, Hančlová I, Šanda M, Cooper A, Kraus T, Brzozowski AM, Jiráček J. Non-equivalent role of inter- and intramolecular hydrogen bonds in the insulin dimer interface. J Biol Chem 2011; 286:36968-77. [PMID: 21880708 PMCID: PMC3196076 DOI: 10.1074/jbc.m111.265249] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/03/2011] [Indexed: 11/06/2022] Open
Abstract
Apart from its role in insulin receptor (IR) activation, the C terminus of the B-chain of insulin is also responsible for the formation of insulin dimers. The dimerization of insulin plays an important role in the endogenous delivery of the hormone and in the administration of insulin to patients. Here, we investigated insulin analogues with selective N-methylations of peptide bond amides at positions B24, B25, or B26 to delineate their structural and functional contribution to the dimer interface. All N-methylated analogues showed impaired binding affinities to IR, which suggests a direct IR-interacting role for the respective amide hydrogens. The dimerization capabilities of analogues were investigated by isothermal microcalorimetry. Selective N-methylations of B24, B25, or B26 amides resulted in reduced dimerization abilities compared with native insulin (K(d) = 8.8 μM). Interestingly, although the N-methylation in [NMeTyrB26]-insulin or [NMePheB24]-insulin resulted in K(d) values of 142 and 587 μM, respectively, the [NMePheB25]-insulin did not form dimers even at high concentrations. This effect may be attributed to the loss of intramolecular hydrogen bonding between NHB25 and COA19, which connects the B-chain β-strand to the core of the molecule. The release of the B-chain β-strand from this hydrogen bond lock may result in its higher mobility, thereby shifting solution equilibrium toward the monomeric state of the hormone. The study was complemented by analyses of two novel analogue crystal structures. All examined analogues crystallized only in the most stable R(6) form of insulin oligomers (even if the dimer interface was totally disrupted), confirming the role of R(6)-specific intra/intermolecular interactions for hexamer stability.
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Affiliation(s)
- Emília Antolíková
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Johan P. Turkenburg
- the York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5YW, United Kingdom, and
| | - Christopher J. Watson
- the York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5YW, United Kingdom, and
| | - Ivona Hančlová
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Miloslav Šanda
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - Alan Cooper
- the School of Chemistry, Glasgow University, College of Science and Engineering, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Tomáš Kraus
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | - A. Marek Brzozowski
- the York Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, York YO10 5YW, United Kingdom, and
| | - Jiří Jiráček
- From the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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40
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Liu M, Hua QX, Hu SQ, Jia W, Yang Y, Saith SE, Whittaker J, Arvan P, Weiss MA. Deciphering the hidden informational content of protein sequences: foldability of proinsulin hinges on a flexible arm that is dispensable in the mature hormone. J Biol Chem 2010; 285:30989-1001. [PMID: 20663888 PMCID: PMC2945590 DOI: 10.1074/jbc.m110.152645] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 07/21/2010] [Indexed: 01/28/2023] Open
Abstract
Protein sequences encode both structure and foldability. Whereas the interrelationship of sequence and structure has been extensively investigated, the origins of folding efficiency are enigmatic. We demonstrate that the folding of proinsulin requires a flexible N-terminal hydrophobic residue that is dispensable for the structure, activity, and stability of the mature hormone. This residue (Phe(B1) in placental mammals) is variably positioned within crystal structures and exhibits (1)H NMR motional narrowing in solution. Despite such flexibility, its deletion impaired insulin chain combination and led in cell culture to formation of non-native disulfide isomers with impaired secretion of the variant proinsulin. Cellular folding and secretion were maintained by hydrophobic substitutions at B1 but markedly perturbed by polar or charged side chains. We propose that, during folding, a hydrophobic side chain at B1 anchors transient long-range interactions by a flexible N-terminal arm (residues B1-B8) to mediate kinetic or thermodynamic partitioning among disulfide intermediates. Evidence for the overall contribution of the arm to folding was obtained by alanine scanning mutagenesis. Together, our findings demonstrate that efficient folding of proinsulin requires N-terminal sequences that are dispensable in the native state. Such arm-dependent folding can be abrogated by mutations associated with β-cell dysfunction and neonatal diabetes mellitus.
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Affiliation(s)
- Ming Liu
- From the Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48109 and
| | - Qing-xin Hua
- the Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Shi-Quan Hu
- the Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Wenhua Jia
- the Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Yanwu Yang
- the Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Sunil Evan Saith
- From the Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48109 and
| | - Jonathan Whittaker
- the Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
| | - Peter Arvan
- From the Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical Center, Ann Arbor, Michigan 48109 and
| | - Michael A. Weiss
- the Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106
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41
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Yang Y, Petkova A, Huang K, Xu B, Hua QX, Ye IJ, Chu YC, Hu SQ, Phillips NB, Whittaker J, Ismail-Beigi F, Mackin RB, Katsoyannis PG, Tycko R, Weiss MA. An Achilles' heel in an amyloidogenic protein and its repair: insulin fibrillation and therapeutic design. J Biol Chem 2010; 285:10806-21. [PMID: 20106984 PMCID: PMC2856287 DOI: 10.1074/jbc.m109.067850] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 01/19/2010] [Indexed: 11/06/2022] Open
Abstract
Insulin fibrillation provides a model for a broad class of amyloidogenic diseases. Conformational distortion of the native monomer leads to aggregation-coupled misfolding. Whereas beta-cells are protected from proteotoxicity by hexamer assembly, fibrillation limits the storage and use of insulin at elevated temperatures. Here, we have investigated conformational distortions of an engineered insulin monomer in relation to the structure of an insulin fibril. Anomalous (13)C NMR chemical shifts and rapid (15)N-detected (1)H-(2)H amide-proton exchange were observed in one of the three classical alpha-helices (residues A1-A8) of the hormone, suggesting a conformational equilibrium between locally folded and unfolded A-chain segments. Whereas hexamer assembly resolves these anomalies in accordance with its protective role, solid-state (13)C NMR studies suggest that the A-chain segment participates in a fibril-specific beta-sheet. Accordingly, we investigated whether helicogenic substitutions in the A1-A8 segment might delay fibrillation. Simultaneous substitution of three beta-branched residues (Ile(A2) --> Leu, Val(A3) --> Leu, and Thr(A8) --> His) yielded an analog with reduced thermodynamic stability but marked resistance to fibrillation. Whereas amide-proton exchange in the A1-A8 segment remained rapid, (13)Calpha chemical shifts exhibited a more helical pattern. This analog is essentially without activity, however, as Ile(A2) and Val(A3) define conserved receptor contacts. To obtain active analogs, substitutions were restricted to A8. These analogs exhibit high receptor-binding affinity; representative potency in a rodent model of diabetes mellitus was similar to wild-type insulin. Although (13)Calpha chemical shifts remain anomalous, significant protection from fibrillation is retained. Together, our studies define an "Achilles' heel" in a globular protein whose repair may enhance the stability of pharmaceutical formulations and broaden their therapeutic deployment in the developing world.
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Affiliation(s)
- Yanwu Yang
- From the Departments of Biochemistry and
| | - Aneta Petkova
- the Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-0520
| | - Kun Huang
- From the Departments of Biochemistry and
| | - Bin Xu
- From the Departments of Biochemistry and
| | | | - I-Ju Ye
- From the Departments of Biochemistry and
| | - Ying-Chi Chu
- the Department of Pharmacology and Biological Chemistry, Mt. Sinai School of Medicine, New York University, New York, New York 10029, and
| | | | | | | | | | - Robert B. Mackin
- the Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Panayotis G. Katsoyannis
- the Department of Pharmacology and Biological Chemistry, Mt. Sinai School of Medicine, New York University, New York, New York 10029, and
| | - Robert Tycko
- the Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892-0520
| | - Michael A. Weiss
- From the Departments of Biochemistry and
- Medicine, Case Western Reserve University, Cleveland, Ohio 44106
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42
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Nakamura T, Takahashi H, Takahashi M, Shimba N, Suzuki EI, Shimada I. Direct Determination of the Insulin−Insulin Receptor Interface Using Transferred Cross-Saturation Experiments. J Med Chem 2010; 53:1917-22. [DOI: 10.1021/jm901099v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takefumi Nakamura
- The Institute of Life Sciences, Ajinomoto Co. Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, Japan
- Japan Biological Informatics Consortium, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
- Biomedicinal Information Research Center, National institute of Advanced Industrial Science and Technology, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
| | - Hideo Takahashi
- Biomedicinal Information Research Center, National institute of Advanced Industrial Science and Technology, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
| | - Mitsuo Takahashi
- The Institute of Life Sciences, Ajinomoto Co. Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, Japan
| | - Nobuhisa Shimba
- The Institute of Life Sciences, Ajinomoto Co. Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, Japan
- Japan Biological Informatics Consortium, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
- Biomedicinal Information Research Center, National institute of Advanced Industrial Science and Technology, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
| | - Ei-ichiro Suzuki
- The Institute of Life Sciences, Ajinomoto Co. Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, Kanagawa, Japan
- Japan Biological Informatics Consortium, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
| | - Ichio Shimada
- Biomedicinal Information Research Center, National institute of Advanced Industrial Science and Technology, 2-41-6 Aomi, Koto-ku, Tokyo, Japan
- The Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan
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43
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Sohma Y, Hua QX, Liu M, Phillips NB, Hu SQ, Whittaker J, Whittaker LJ, Ng A, Roberts CT, Arvan P, Kent SBH, Weiss MA. Contribution of residue B5 to the folding and function of insulin and IGF-I: constraints and fine-tuning in the evolution of a protein family. J Biol Chem 2009; 285:5040-55. [PMID: 19959476 DOI: 10.1074/jbc.m109.062992] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proinsulin exhibits a single structure, whereas insulin-like growth factors refold as two disulfide isomers in equilibrium. Native insulin-related growth factor (IGF)-I has canonical cystines (A6-A11, A7-B7, and A20-B19) maintained by IGF-binding proteins; IGF-swap has alternative pairing (A7-A11, A6-B7, and A20-B19) and impaired activity. Studies of mini-domain models suggest that residue B5 (His in insulin and Thr in IGFs) governs the ambiguity or uniqueness of disulfide pairing. Residue B5, a site of mutation in proinsulin causing neonatal diabetes, is thus of broad biophysical interest. Here, we characterize reciprocal B5 substitutions in the two proteins. In insulin, His(B5) --> Thr markedly destabilizes the hormone (DeltaDeltaG(u) 2.0 +/- 0.2 kcal/mol), impairs chain combination, and blocks cellular secretion of proinsulin. The reciprocal IGF-I substitution Thr(B5) --> His (residue 4) specifies a unique structure with native (1)H NMR signature. Chemical shifts and nuclear Overhauser effects are similar to those of native IGF-I. Whereas wild-type IGF-I undergoes thiol-catalyzed disulfide exchange to yield IGF-swap, His(B5)-IGF-I retains canonical pairing. Chemical denaturation studies indicate that His(B5) does not significantly enhance thermodynamic stability (DeltaDeltaG(u) 0.2 +/- 0.2 kcal/mol), implying that the substitution favors canonical pairing by destabilizing competing folds. Whereas the activity of Thr(B5)-insulin is decreased 5-fold, His(B5)-IGF-I exhibits 2-fold increased affinity for the IGF receptor and augmented post-receptor signaling. We propose that conservation of Thr(B5) in IGF-I, rescued from structural ambiguity by IGF-binding proteins, reflects fine-tuning of signal transduction. In contrast, the conservation of His(B5) in insulin highlights its critical role in insulin biosynthesis.
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Affiliation(s)
- Youhei Sohma
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois 60637, USA
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44
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Xu B, Huang K, Chu YC, Hu SQ, Nakagawa S, Wang S, Wang RY, Whittaker J, Katsoyannis PG, Weiss MA. Decoding the cryptic active conformation of a protein by synthetic photoscanning: insulin inserts a detachable arm between receptor domains. J Biol Chem 2009; 284:14597-608. [PMID: 19321435 PMCID: PMC2682907 DOI: 10.1074/jbc.m900087200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 03/20/2009] [Indexed: 12/15/2022] Open
Abstract
Proteins evolve in a fitness landscape encompassing a complex network of biological constraints. Because of the interrelation of folding, function, and regulation, the ground-state structure of a protein may be inactive. A model is provided by insulin, a vertebrate hormone central to the control of metabolism. Whereas native assembly mediates storage within pancreatic beta-cells, the active conformation of insulin and its mode of receptor binding remain elusive. Here, functional surfaces of insulin were probed by photocross-linking of an extensive set of azido derivatives constructed by chemical synthesis. Contacts are circumferential, suggesting that insulin is encaged within its receptor. Mapping of photoproducts to the hormone-binding domains of the insulin receptor demonstrated alternating contacts by the B-chain beta-strand (residues B24-B28). Whereas even-numbered probes (at positions B24 and B26) contact the N-terminal L1 domain of the alpha-subunit, odd-numbered probes (at positions B25 and B27) contact its C-terminal insert domain. This alternation corresponds to the canonical structure of abeta-strand (wherein successive residues project in opposite directions) and so suggests that the B-chain inserts between receptor domains. Detachment of a receptor-binding arm enables photo engagement of surfaces otherwise hidden in the free hormone. The arm and associated surfaces contain sites also required for nascent folding and self-assembly of storage hexamers. The marked compression of structural information within a short polypeptide sequence rationalizes the diversity of diabetes-associated mutations in the insulin gene. Our studies demonstrate that photoscanning mutagenesis can decode the active conformation of a protein and so illuminate cryptic constraints underlying its evolution.
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Affiliation(s)
- Bin Xu
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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45
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Todorova N, Marinelli F, Piana S, Yarovsky I. Exploring the folding free energy landscape of insulin using bias exchange metadynamics. J Phys Chem B 2009; 113:3556-64. [PMID: 19243106 DOI: 10.1021/jp809776v] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The bias exchange metadynamics (BE-META) technique was applied to investigate the folding mechanism of insulin, one of the most studied and biologically important proteins. The BE-META simulations were performed starting from an extended conformation of chain B of insulin, using only eight replicas and seven reaction coordinates. The folded state, together with the intermediate states along the folding pathway were identified and their free energy was determined. Three main basins were found separated from one another by a large free energy barrier. The characteristic native fold of chain B was observed in one basin, while the other two most populated basins contained "molten-globule" conformations stabilized by electrostatic and hydrophobic interactions, respectively. Transitions between the three basins occur on the microsecond time scale. The implications and relevance of this finding to the folding mechanisms of insulin were investigated.
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Affiliation(s)
- Nevena Todorova
- Applied Physics, School of Applied Sciences, RMIT University, Melbourne, Victoria, Australia
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46
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Hua QX, Xu B, Huang K, Hu SQ, Nakagawa S, Jia W, Wang S, Whittaker J, Katsoyannis PG, Weiss MA. Enhancing the activity of a protein by stereospecific unfolding: conformational life cycle of insulin and its evolutionary origins. J Biol Chem 2009; 284:14586-96. [PMID: 19321436 DOI: 10.1074/jbc.m900085200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A central tenet of molecular biology holds that the function of a protein is mediated by its structure. An inactive ground-state conformation may nonetheless be enjoined by the interplay of competing biological constraints. A model is provided by insulin, well characterized at atomic resolution by x-ray crystallography. Here, we demonstrate that the activity of the hormone is enhanced by stereospecific unfolding of a conserved structural element. A bifunctional beta-strand mediates both self-assembly (within beta-cell storage vesicles) and receptor binding (in the bloodstream). This strand is anchored by an invariant side chain (Phe(B24)); its substitution by Ala leads to an unstable but native-like analog of low activity. Substitution by d-Ala is equally destabilizing, and yet the protein diastereomer exhibits enhanced activity with segmental unfolding of the beta-strand. Corresponding photoactivable derivatives (containing l- or d-para-azido-Phe) cross-link to the insulin receptor with higher d-specific efficiency. Aberrant exposure of hydrophobic surfaces in the analogs is associated with accelerated fibrillation, a form of aggregation-coupled misfolding associated with cellular toxicity. Conservation of Phe(B24), enforced by its dual role in native self-assembly and induced fit, thus highlights the implicit role of misfolding as an evolutionary constraint. Whereas classical crystal structures of insulin depict its storage form, signaling requires engagement of a detachable arm at an extended receptor interface. Because this active conformation resembles an amyloidogenic intermediate, we envisage that induced fit and self-assembly represent complementary molecular adaptations to potential proteotoxicity. The cryptic threat of misfolding poses a universal constraint in the evolution of polypeptide sequences.
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Affiliation(s)
- Qing-xin Hua
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio 44106, USA
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47
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Manolopoulou M, Guo Q, Malito E, Schilling AB, Tang WJ. Molecular basis of catalytic chamber-assisted unfolding and cleavage of human insulin by human insulin-degrading enzyme. J Biol Chem 2009; 284:14177-88. [PMID: 19321446 DOI: 10.1074/jbc.m900068200] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin is a hormone vital for glucose homeostasis, and insulin-degrading enzyme (IDE) plays a key role in its clearance. IDE exhibits a remarkable specificity to degrade insulin without breaking the disulfide bonds that hold the insulin A and B chains together. Using Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to obtain high mass accuracy, and electron capture dissociation (ECD) to selectively break the disulfide bonds in gas phase fragmentation, we determined the cleavage sites and composition of human insulin fragments generated by human IDE. Our time-dependent analysis of IDE-digested insulin fragments reveals that IDE is highly processive in its initial cleavage at the middle of both the insulin A and B chains. This ensures that IDE effectively splits insulin into inactive N- and C-terminal halves without breaking the disulfide bonds. To understand the molecular basis of the recognition and unfolding of insulin by IDE, we determined a 2.6-A resolution insulin-bound IDE structure. Our structure reveals that IDE forms an enclosed catalytic chamber that completely engulfs and intimately interacts with a partially unfolded insulin molecule. This structure also highlights how the unique size, shape, charge distribution, and exosite of the IDE catalytic chamber contribute to its high affinity ( approximately 100 nm) for insulin. In addition, this structure shows how IDE utilizes the interaction of its exosite with the N terminus of the insulin A chain as well as other properties of the catalytic chamber to guide the unfolding of insulin and allowing for the processive cleavages.
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Affiliation(s)
- Marika Manolopoulou
- Ben-May Department for Cancer Research, University of Chicago, Chicago, Illinois 60637, USA
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48
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Abstract
Crystal structures of insulin are remarkable for a long-range reorganization among three families of hexamers (designated T(6), T(3)R(3)(f), and R(6)). Although these structures are well characterized at atomic resolution, the biological implications of the TR transition remain the subject of speculation. Recent studies indicate that such allostery reflects a structural switch between distinct folding-competent and active conformations. Stereospecific modulation of this switch by corresponding d- and l-amino-acid substitutions yields reciprocal effects on protein stability and receptor-binding activity. Naturally occurring human mutations at the site of conformational change impair the folding of proinsulin and cause permanent neonatal-onset diabetes mellitus. The repertoire of classical structures thus foreshadows the conformational lifecycle of insulin in vivo. By highlighting the richness of information provided by protein crystallography-even in a biological realm far removed from conditions of crystallization-these findings validate the prescient insights of the late D. C. Hodgkin. Future studies of the receptor-bound structure of insulin may enable design of novel agonists for the treatment of diabetes mellitus.
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49
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Bocian W, Borowicz P, Mikołajczyk J, Sitkowski J, Tarnowska A, Bednarek E, Głąbski T, Tejchman-Małecka B, Bogiel M, Kozerski L. NMR structure of biosynthetic engineered human insulin monomer B31Lys-B32Argin water/acetonitrile solution. Comparison with the solution structure of native human insulin monomer. Biopolymers 2008; 89:820-30. [DOI: 10.1002/bip.21018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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50
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Wan ZL, Huang K, Hu SQ, Whittaker J, Weiss MA. The structure of a mutant insulin uncouples receptor binding from protein allostery. An electrostatic block to the TR transition. J Biol Chem 2008; 283:21198-210. [PMID: 18492668 PMCID: PMC2475698 DOI: 10.1074/jbc.m800235200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 05/01/2008] [Indexed: 11/06/2022] Open
Abstract
The zinc insulin hexamer undergoes allosteric reorganization among three conformational states, designated T(6), T(3)R(3)(f), and R(6). Although the free monomer in solution (the active species) resembles the classical T-state, an R-like conformational change is proposed to occur upon receptor binding. Here, we distinguish between the conformational requirements of receptor binding and the crystallographic TR transition by design of an active variant refractory to such reorganization. Our strategy exploits the contrasting environments of His(B5) in wild-type structures: on the T(6) surface but within an intersubunit crevice in R-containing hexamers. The TR transition is associated with a marked reduction in His(B5) pK(a), in turn predicting that a positive charge at this site would destabilize the R-specific crevice. Remarkably, substitution of His(B5) (conserved among eutherian mammals) by Arg (occasionally observed among other vertebrates) blocks the TR transition, as probed in solution by optical spectroscopy. Similarly, crystallization of Arg(B5)-insulin in the presence of phenol (ordinarily a potent inducer of the TR transition) yields T(6) hexamers rather than R(6) as obtained in control studies of wild-type insulin. The variant structure, determined at a resolution of 1.3A, closely resembles the wild-type T(6) hexamer. Whereas Arg(B5) is exposed on the protein surface, its side chain participates in a solvent-stabilized network of contacts similar to those involving His(B5) in wild-type T-states. The substantial receptor-binding activity of Arg(B5)-insulin (40% relative to wild type) demonstrates that the function of an insulin monomer can be uncoupled from its allosteric reorganization within zinc-stabilized hexamers.
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Affiliation(s)
- Zhu-li Wan
- Departments of Biochemistry
and Nutrition, Case Western Reserve
University School of Medicine, Cleveland, Ohio 44106
| | - Kun Huang
- Departments of Biochemistry
and Nutrition, Case Western Reserve
University School of Medicine, Cleveland, Ohio 44106
| | - Shi-Quan Hu
- Departments of Biochemistry
and Nutrition, Case Western Reserve
University School of Medicine, Cleveland, Ohio 44106
| | - Jonathan Whittaker
- Departments of Biochemistry
and Nutrition, Case Western Reserve
University School of Medicine, Cleveland, Ohio 44106
| | - Michael A. Weiss
- Departments of Biochemistry
and Nutrition, Case Western Reserve
University School of Medicine, Cleveland, Ohio 44106
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