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Levintov L, Gorai B, Vashisth H. Spontaneous Dimerization and Distinct Packing Modes of Transmembrane Domains in Receptor Tyrosine Kinases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.09.593448. [PMID: 38798363 PMCID: PMC11118388 DOI: 10.1101/2024.05.09.593448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The insulin receptor (IR) and the insulin-like growth factor-1 receptor (IGF1R) are homodimeric transmembrane glycoproteins that transduce signals across the membrane on binding of extracellular peptide ligands. The structures of IR/IGF1R fragments in apo and liganded states have revealed that the extracellular subunits of these receptors adopt Λ-shaped configurations to which are connected the intracellular tyrosine kinase (TK) domains. The binding of peptide ligands induces structural transitions in the extracellular subunits leading to potential dimerization of transmembrane domains (TMDs) and autophosphorylation in TKs. However, the activation mechanisms of IR/IGF1R, especially the role of TMDs in coordinating signal-inducing structural transitions, remain poorly understood, in part due to the lack of structures of full-length receptors in apo or liganded states. While atomistic simulations of IR/IGF1R TMDs showed that these domains can dimerize in single component membranes, spontaneous unbiased dimerization in a plasma membrane having physiologically representative lipid composition has not been observed. We address this limitation by employing coarse-grained (CG) molecular dynamics simulations to probe the dimerization propensity of IR/IGF1R TMDs. We observed that TMDs in both receptors spontaneously dimerized independent of their initial orientations in their dissociated states, signifying their natural propensity for dimerization. In the dimeric state, IR TMDs predominantly adopted X-shaped configurations with asymmetric helical packing and significant tilt relative to the membrane normal, while IGF1R TMDs adopted symmetric V-shaped or parallel configurations with either no tilt or a small tilt relative to the membrane normal. Our results suggest that IR/IGF1R TMDs spontaneously dimerize and adopt distinct dimerized configurations.
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Affiliation(s)
- Lev Levintov
- Department of Chemical Engineering and Bioengineering, University of New Hampshire, Durham 03824, New Hampshire, USA
| | - Biswajit Gorai
- Institute of Chemistry, Technical University of Berlin, Berlin 10623, Germany
| | - Harish Vashisth
- Department of Chemical Engineering and Bioengineering, University of New Hampshire, Durham 03824, New Hampshire, USA
- Department of Chemistry, University of New Hampshire, Durham 03824, New Hampshire, USA
- Integrated Applied Mathematics Program, University of New Hampshire, Durham 03824, New Hampshire, USA
- Molecular and Cellular Biotechnology Program, University of New Hampshire, Durham 03824, New Hampshire, USA
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Kalitnik A, Szefczyk M, Wojciechowska AW, Wojciechowski JW, Gąsior-Głogowska M, Olesiak-Bańska J, Kotulska M. Cytotoxic Staphylococcus aureus PSMα3 inhibits the aggregation of human insulin in vitro. Phys Chem Chem Phys 2024; 26:15587-15599. [PMID: 38757742 DOI: 10.1039/d4cp00669k] [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: 05/18/2024]
Abstract
Phenol-soluble modulins (PSMs) are extracellular short amphipathic peptides secreted by the bacteria Staphylococcus aureus (S. aureus). They play an essential role in the bacterial lifecycle, biofilm formation, and stabilisation. From the PSM family, PSMα3 has been of special interest recently due to its cytotoxicity and highly stable α-helical conformation, which also remains in its amyloid fibrils. In particular, PSMα3 fibrils were shown to be composed of self-associating "sheets" of α-helices oriented perpendicular to the fibril axis, mimicking the architecture of canonical cross-β fibrils. Therefore, they were called cross-α-fibrils. PSMα3 was synthesised and verified for identity with wild-type sequences (S. aureus). Then, using several experimental techniques, we evaluated its propensity for in vitro aggregation. According to our findings, synthetic PSMα3 (which lacks the N-terminal formyl groups found in bacteria) does not form amyloid fibrils and maintains α-helical conformation in a soluble monomeric form for several days of incubation. We also evaluated the influence of PSMα3 on human insulin fibrillation in vitro, using a variety of experimental approaches in combination with computational molecular studies. First, it was shown that PSMα3 drastically inhibits the fibrillation of human insulin. The anti-fibrillation effect of PSMα3 was concentration-dependent and required a concentration ratio of PSMα3: insulin equal to or above 1 : 100. Molecular modelling revealed that PSMα3 most likely inhibits the production of insulin primary nuclei by competing for residues involved in its dimerization.
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Affiliation(s)
- Aleksandra Kalitnik
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Monika Szefczyk
- Department of Bioorganic Chemistry, Faculty of Chemistry, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Alicja W Wojciechowska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Jakub W Wojciechowski
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Marlena Gąsior-Głogowska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
| | - Joanna Olesiak-Bańska
- Institute of Advanced Materials, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Małgorzata Kotulska
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland.
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Bayrami S, Chamani M, JamaliMoghadamSiahkali S, SeyedAlinaghi S, Shirmard LR, Bayrami S, Javar HA, Ghahremani MH, Amini M, Tehrani MR, Shahsavari S, Dorkoosh FA. Preparation, Characterization and In vitro Evaluation of Insulin-PHBV Nanoparticles / Alginate Hydrogel Composite System for Prolonged Delivery of Insulin. J Pharm Sci 2024:S0022-3549(24)00094-7. [PMID: 38508339 DOI: 10.1016/j.xphs.2024.03.010] [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: 11/21/2023] [Revised: 03/14/2024] [Accepted: 03/14/2024] [Indexed: 03/22/2024]
Abstract
PURPOSE In the present study, biodegradable poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles (NPs) containing insulin were loaded in sodium alginate/jeffamine (ALG/jeff) hydrogel for prolonged delivery of insulin. The main aim of this work was to fabricate an efficient insulin delivery system to improve patient adherence by decreasing the repetition of injections. METHODS Swelling and morphological properties and crosslinking efficiency of ALG/jeff hydrogel were assessed. The composite hydrogel was prepared by adding PHBV NPs to ALG/jeff hydrogel concurrently with crosslinking process. The morphology and loading capacity of composite hydrogel were analyzed. RESULTS Circular dichroism measurement demonstrated that insulin remains stable following fabrication process. The release profile exhibited 54.6 % insulin release from composite hydrogel within 31 days with minor initial burst release equated to nanoparticles and hydrogels. MTT cell viability analysis was performed by applying L-929 cell line and no cytotoxic effect was observed. CONCLUSIONS Favorable results clearly introduced fabricated composite hydrogel as an excellent candidate for drug delivery systems and also paves the route for prolonged delivery systems of other proteins.
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Affiliation(s)
- Samane Bayrami
- Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Mehdi Chamani
- Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | | | - SeyedAhmad SeyedAlinaghi
- Iranian Research Center for HIV/AIDS, Iranian Institute for Reduction of High Risk Behaviors, Tehran University of Medical Sciences, Tehran, Iran
| | - Leila Rezaie Shirmard
- Department of Pharmaceutics, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Sepide Bayrami
- Islamic Azad University, North Tehran Branch, Faculty of Bioscience, Tehran, Iran
| | - Hamid Akbari Javar
- Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Hossein Ghahremani
- Department of Toxicology-Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Amini
- Department of Medicinal Chemistry, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran; Drug Design and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Morteza Rafiee Tehrani
- Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
| | - Shadab Shahsavari
- Chemical Engineering Department, Varamin-Pishva Branch, Islamic Azad University, Varamin, Iran
| | - Farid Abedin Dorkoosh
- Department of Pharmaceutics, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran; Medical Biomaterial Research Centre (MBRC), Tehran University of Medical Sciences, Tehran 14399-56131, Iran.
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Rohilla K, Pandey MK. Computational Approach to Elucidating Insulin-Protamine Binding Interactions and Dynamics in Insulin NPH Formulations. ACS OMEGA 2024; 9:4857-4869. [PMID: 38313521 PMCID: PMC10831847 DOI: 10.1021/acsomega.3c08445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/28/2023] [Accepted: 12/28/2023] [Indexed: 02/06/2024]
Abstract
Insulin NPH is an intermediate-acting insulin. Its protracted action profile is due to the formation of microcrystalline suspensions when insulin is complexed with a basic peptide protamine, zinc ion, and phenolic ligands. Despite advancements in analytical techniques, the binding epitope and binding mode of the protamine in the insulin-protamine complex are still unknown. In this study, we used bioinformatics tools such as molecular docking and molecular dynamics (MD) simulations to compute the binding sites and energetics of the insulin-protamine complex. We have taken four naturally occurring protamine peptides that are independently docked with the insulin R6 hexamer and subjected them to 200 ns MD simulations to observe the dynamics of the complexes and estimate the binding energies. The arginine-rich protamine peptides were found to bind on the surface of the insulin hexamer through hydrogen bonding, hydrophobic, and electrostatic interactions well supported by the calculated negative binding energies. The overall structure of the insulin hexamer was retained upon binding, highlighting its dynamic stability in the complex. Furthermore, the residues at the termini of the protamine peptides in the complex were seen to be highly dynamic, which stabilize toward the end of the simulation.
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Affiliation(s)
- Ketan
Kumar Rohilla
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India
| | - Manoj Kumar Pandey
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India
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Peluso P, Chankvetadze B. Recent developments in molecular modeling tools and applications related to pharmaceutical and biomedical research. J Pharm Biomed Anal 2024; 238:115836. [PMID: 37939549 DOI: 10.1016/j.jpba.2023.115836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 09/21/2023] [Accepted: 10/30/2023] [Indexed: 11/10/2023]
Abstract
In modern pharmaceutical and biomedical research, molecular modeling represents a useful tool to explore processes and their mechanistic bases at the molecular level. Integrating experimental and virtual analysis is a fruitful approach to study ligand-receptor interaction in chemical, biochemical and biological environments. In these fields, molecular docking and molecular dynamics are considered privileged techniques for modeling (bio)macromolecules and related complexes. This review aims to present the current landscape of molecular modeling in pharmaceutical and biomedical research by examining selected representative applications published in the last years and highlighting current topics and trends of this field. Thus, a systematic compilation of all published literature has not been attempted herein. After a brief overview of the main theoretical and computational tools used to investigate mechanisms at molecular level, recent applications of molecular modeling in drug discovery, ligand binding and for studying protein conformation and function will be discussed. Furthermore, specific sections will be devoted to the application of molecular modeling for unravelling enantioselective mechanisms underlying the enantioseparation of chiral compounds of pharmaceutical and biomedical interest as well as for studying new forms of noncovalent interactivity identified in biochemical and biological environments. The general aim of this review is to provide the reader with a modern overview of the topic, highlighting advancements and outlooks as well as drawbacks and pitfalls still affecting the applicability of theoretical and computational methods in the field of pharmaceutical and biomedical research.
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Affiliation(s)
- Paola Peluso
- Istituto di Chimica Biomolecolare ICB-CNR, Sede secondaria di Sassari, Traversa La Crucca 3, Regione Baldinca, Li Punti, 07100 Sassari, Italy.
| | - Bezhan Chankvetadze
- Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, 0179 Tbilisi, Georgia
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Wang X, Sun H, Mu T. Materials and structure of polysaccharide-based delivery carriers for oral insulin: A review. Carbohydr Polym 2024; 323:121364. [PMID: 37940264 DOI: 10.1016/j.carbpol.2023.121364] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 08/24/2023] [Accepted: 09/02/2023] [Indexed: 11/10/2023]
Abstract
Diabetes mellitus is a chronic metabolic disease that affects >500 million patients worldwide. Subcutaneous injection of insulin is the most effective treatment at present. However, regular needle injections will cause pain, inflammation, and other adverse consequences. In recent years, significant progress has been made in non-injectable insulin preparations. Oral administration is the best way of administration due to its simplicity, convenience, and good patient compliance. However, oral insulin delivery is hindered by many physiological barriers in the gastrointestinal tract, resulting in the low relative bioavailability of direct oral insulin delivery. To improve the relative bioavailability, a variety of insulin delivery vectors have been developed. Polysaccharides are used to achieve safe and effective insulin loading due to their excellent biocompatibility and protein affinity. The functional characteristics of polysaccharide-based delivery carriers, such as pH responsiveness, mucosal adhesion, and further functionalization modifications, enhance the gastrointestinal absorption and bioavailability of insulin. This paper reviews the materials and structures of oral insulin polysaccharide-based carriers, providing ideas for further improving the relative bioavailability of oral insulin.
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Affiliation(s)
- Xinran Wang
- Laboratory of Food Chemistry and Nutrition Science, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, No. 2 Yuan Ming Yuan West Road, Haidian District, P.O. Box 5109, Beijing 100193, China
| | - Hongnan Sun
- Laboratory of Food Chemistry and Nutrition Science, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, No. 2 Yuan Ming Yuan West Road, Haidian District, P.O. Box 5109, Beijing 100193, China.
| | - Taihua Mu
- Laboratory of Food Chemistry and Nutrition Science, Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, No. 2 Yuan Ming Yuan West Road, Haidian District, P.O. Box 5109, Beijing 100193, China.
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Galzitskaya OV, Grishin SY, Glyakina AV, Dovidchenko NV, Konstantinova AV, Kravchenko SV, Surin AK. The Strategies of Development of New Non-Toxic Inhibitors of Amyloid Formation. Int J Mol Sci 2023; 24:ijms24043781. [PMID: 36835194 PMCID: PMC9964835 DOI: 10.3390/ijms24043781] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
In recent years, due to the aging of the population and the development of diagnostic medicine, the number of identified diseases associated with the accumulation of amyloid proteins has increased. Some of these proteins are known to cause a number of degenerative diseases in humans, such as amyloid-beta (Aβ) in Alzheimer's disease (AD), α-synuclein in Parkinson's disease (PD), and insulin and its analogues in insulin-derived amyloidosis. In this regard, it is important to develop strategies for the search and development of effective inhibitors of amyloid formation. Many studies have been carried out aimed at elucidating the mechanisms of amyloid aggregation of proteins and peptides. This review focuses on three amyloidogenic peptides and proteins-Aβ, α-synuclein, and insulin-for which we will consider amyloid fibril formation mechanisms and analyze existing and prospective strategies for the development of effective and non-toxic inhibitors of amyloid formation. The development of non-toxic inhibitors of amyloid will allow them to be used more effectively for the treatment of diseases associated with amyloid.
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Affiliation(s)
- Oxana V. Galzitskaya
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Russia
- Correspondence:
| | - Sergei Y. Grishin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia
| | - Anna V. Glyakina
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- Institute of Mathematical Problems of Biology RAS, The Branch of Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Nikita V. Dovidchenko
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
| | - Anastasiia V. Konstantinova
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- Faculty of Biotechnology, Lomonosov Moscow State University, 119991 Moscow, Russia
| | - Sergey V. Kravchenko
- Institute of Environmental and Agricultural Biology (X-BIO), Tyumen State University, 625003 Tyumen, Russia
| | - Alexey K. Surin
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- The Branch of the Institute of Bioorganic Chemistry, Russian Academy of Sciences, 142290 Pushchino, Russia
- State Research Center for Applied Microbiology and Biotechnology, 142279 Obolensk, Russia
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Cook TW, Wilstermann AM, Mitchell JT, Arnold NE, Rajasekaran S, Bupp CP, Prokop JW. Understanding Insulin in the Age of Precision Medicine and Big Data: Under-Explored Nature of Genomics. Biomolecules 2023; 13:257. [PMID: 36830626 PMCID: PMC9953665 DOI: 10.3390/biom13020257] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/20/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023] Open
Abstract
Insulin is amongst the human genome's most well-studied genes/proteins due to its connection to metabolic health. Within this article, we review literature and data to build a knowledge base of Insulin (INS) genetics that influence transcription, transcript processing, translation, hormone maturation, secretion, receptor binding, and metabolism while highlighting the future needs of insulin research. The INS gene region has 2076 unique variants from population genetics. Several variants are found near the transcriptional start site, enhancers, and following the INS transcripts that might influence the readthrough fusion transcript INS-IGF2. This INS-IGF2 transcript splice site was confirmed within hundreds of pancreatic RNAseq samples, lacks drift based on human genome sequencing, and has possible elevated expression due to viral regulation within the liver. Moreover, a rare, poorly characterized African population-enriched variant of INS-IGF2 results in a loss of the stop codon. INS transcript UTR variants rs689 and rs3842753, associated with type 1 diabetes, are found in many pancreatic RNAseq datasets with an elevation of the 3'UTR alternatively spliced INS transcript. Finally, by combining literature, evolutionary profiling, and structural biology, we map rare missense variants that influence preproinsulin translation, proinsulin processing, dimer/hexamer secretory storage, receptor activation, and C-peptide detection for quasi-insulin blood measurements.
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Affiliation(s)
- Taylor W. Cook
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | | | - Jackson T. Mitchell
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Nicholas E. Arnold
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Surender Rajasekaran
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
- Office of Research, Corewell Health, Grand Rapids, MI 49503, USA
| | - Caleb P. Bupp
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
- Division of Medical Genetics, Corewell Health, Grand Rapids, MI 49503, USA
| | - Jeremy W. Prokop
- Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 48824, USA
- Office of Research, Corewell Health, Grand Rapids, MI 49503, USA
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Gorai B, Vashisth H. Structural models of viral insulin-like peptides and their analogs. Proteins 2023; 91:62-73. [PMID: 35962629 PMCID: PMC9772067 DOI: 10.1002/prot.26410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 07/21/2022] [Accepted: 08/09/2022] [Indexed: 12/24/2022]
Abstract
The insulin receptor (IR), the insulin-like growth factor-1 receptor (IGF1R), and the insulin/IGF1 hybrid receptors (hybR) are homologous transmembrane receptors. The peptide ligands, insulin and IGF1, exhibit significant structural homology and can bind to each receptor via site-1 and site-2 residues with distinct affinities. The variants of the Iridoviridae virus family show capability in expressing single-chain insulin/IGF1 like proteins, termed viral insulin-like peptides (VILPs), which can stimulate receptors from the insulin family. The sequences of VILPs lacking the central C-domain (dcVILPs) are known, but their structures in unbound and receptor-bound states have not been resolved to date. We report all-atom structural models of three dcVILPs (dcGIV, dcSGIV, and dcLCDV1) and their complexes with the receptors (μIR, μIGF1R, and μhybR), and probed the peptide/receptor interactions in each system using all-atom molecular dynamics (MD) simulations. Based on the nonbonded interaction energies computed between each residue of peptides (insulin and dcVILPs) and the receptors, we provide details on residues establishing significant interactions. The observed site-1 insulin/μIR interactions are consistent with previous experimental studies, and a residue-level comparison of interactions of peptides (insulin and dcVILPs) with the receptors revealed that, due to sequence differences, dcVILPs also establish some interactions distinct from those between insulin and IR. We also designed insulin analogs and report enhanced interactions between some analogs and the receptors.
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Affiliation(s)
- Biswajit Gorai
- Department of Chemical Engineering, University of New Hampshire, Durham, NH 03824, USA
| | - Harish Vashisth
- Department of Chemical Engineering, University of New Hampshire, Durham, NH 03824, USA
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