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Dias AMGC, Moreira IP, Lychko I, Lopes Soares C, Nurrito A, Moura Barbosa AJ, Lutz-Bueno V, Mezzenga R, Carvalho AL, Pina AS, Roque ACA. Hierarchical self-assembly of a reflectin-derived peptide. Front Chem 2023; 11:1267563. [PMID: 37810582 PMCID: PMC10552760 DOI: 10.3389/fchem.2023.1267563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 09/05/2023] [Indexed: 10/10/2023] Open
Abstract
Reflectins are a family of intrinsically disordered proteins involved in cephalopod camouflage, making them an interesting source for bioinspired optical materials. Understanding reflectin assembly into higher-order structures by standard biophysical methods enables the rational design of new materials, but it is difficult due to their low solubility. To address this challenge, we aim to understand the molecular self-assembly mechanism of reflectin's basic unit-the protopeptide sequence YMDMSGYQ-as a means to understand reflectin's assembly phenomena. Protopeptide self-assembly was triggered by different environmental cues, yielding supramolecular hydrogels, and characterized by experimental and theoretical methods. Protopeptide films were also prepared to assess optical properties. Our results support the hypothesis for the protopeptide aggregation model at an atomistic level, led by hydrophilic and hydrophobic interactions mediated by tyrosine residues. Protopeptide-derived films were optically active, presenting diffuse reflectance in the visible region of the light spectrum. Hence, these results contribute to a better understanding of the protopeptide structural assembly, crucial for the design of peptide- and reflectin-based functional materials.
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Affiliation(s)
- Ana Margarida Gonçalves Carvalho Dias
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Inês Pimentel Moreira
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Iana Lychko
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Cátia Lopes Soares
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Arianna Nurrito
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Arménio Jorge Moura Barbosa
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Viviane Lutz-Bueno
- Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
- Paul Scherrer Institute, Villigen, Switzerland
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Ana Luísa Carvalho
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Ana Sofia Pina
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Ana Cecília Afonso Roque
- Associate Laboratory i4HB—Institute for Health and Bioeconomy, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
- UCIBIO—Applied Molecular Biosciences Unit, Department of Chemistry, School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal
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Chatterjee A, Pratakshya P, Kwansa AL, Kaimal N, Cannon AH, Sartori B, Marmiroli B, Orins H, Feng Z, Drake S, Couvrette J, Le L, Bernstorff S, Yingling YG, Gorodetsky AA. Squid Skin Cell-Inspired Refractive Index Mapping of Cells, Vesicles, and Nanostructures. ACS Biomater Sci Eng 2023; 9:978-990. [PMID: 36692450 DOI: 10.1021/acsbiomaterials.2c00088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The fascination with the optical properties of naturally occurring systems has been driven in part by nature's ability to produce a diverse palette of vibrant colors from a relatively small number of common structural motifs. Within this context, some cephalopod species have evolved skin cells called iridophores and leucophores whose constituent ultrastructures reflect light in different ways but are composed of the same high refractive index material─a protein called reflectin. Although such natural optical systems have attracted much research interest, measuring the refractive indices of biomaterial-based structures across multiple different environments and establishing theoretical frameworks for accurately describing the obtained refractive index values has proven challenging. Herein, we employ a synergistic combination of experimental and computational methodologies to systematically map the three-dimensional refractive index distributions of model self-assembled reflectin-based structures both in vivo and in vitro. When considered together, our findings may improve understanding of squid skin cell functionality, augment existing methods for characterizing protein-based optical materials, and expand the utility of emerging holotomographic microscopy techniques.
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Affiliation(s)
- Atrouli Chatterjee
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Preeta Pratakshya
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Albert L Kwansa
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Nikhil Kaimal
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Andrew H Cannon
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Barbara Sartori
- Institute of Inorganic Chemistry, Graz University of Technology, Graz 8010, Austria
| | - Benedetta Marmiroli
- Institute of Inorganic Chemistry, Graz University of Technology, Graz 8010, Austria
| | - Helen Orins
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Zhijing Feng
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Samantha Drake
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Justin Couvrette
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - LeAnn Le
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | | | - Yaroslava G Yingling
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Alon A Gorodetsky
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States.,Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States.,Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697, United States
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Levenson R, Bracken C, Sharma C, Santos J, Arata C, Malady B, Morse DE. Calibration between trigger and color: Neutralization of a genetically encoded coulombic switch and dynamic arrest precisely tune reflectin assembly. J Biol Chem 2019; 294:16804-16815. [PMID: 31558609 DOI: 10.1074/jbc.ra119.010339] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 09/14/2019] [Indexed: 12/28/2022] Open
Abstract
Reflectin proteins are widely distributed in reflective structures in cephalopods. However, only in loliginid squids are they and the subwavelength photonic structures they control dynamically tunable, driving changes in skin color for camouflage and communication. The reflectins are block copolymers with repeated canonical domains interspersed with cationic linkers. Neurotransmitter-activated signal transduction culminates in catalytic phosphorylation of the tunable reflectins' cationic linkers; the resulting charge neutralization overcomes coulombic repulsion to progressively allow condensation, folding, and assembly into multimeric spheres of tunable well-defined size and low polydispersity. Here, we used dynamic light scattering, transmission EM, CD, atomic force microscopy, and fluorimetry to analyze the structural transitions of reflectins A1 and A2. We also analyzed the assembly behavior of phosphomimetic, deletion, and other mutants in conjunction with pH titration as an in vitro surrogate of phosphorylation. Our experiments uncovered a previously unsuspected, precisely predictive relationship between the extent of neutralization of a reflectin's net charge density and the size of resulting multimeric protein assemblies of narrow polydispersity. Comparisons of mutants revealed that this sensitivity to neutralization resides in the linkers and is spatially distributed along the protein. Imaging of large particles and analysis of sequence composition suggested that assembly may proceed through a dynamically arrested liquid-liquid phase-separated intermediate. Intriguingly, it is this dynamic arrest that enables the observed fine-tuning by charge and the resulting calibration between neuronal trigger and color in the squid. These results offer insights into the basis of reflectin-based biophotonics, opening paths for the design of new materials with tunable properties.
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Affiliation(s)
- Robert Levenson
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
| | - Colton Bracken
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
| | - Cristian Sharma
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
| | - Jerome Santos
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
| | - Claire Arata
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
| | - Brandon Malady
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
| | - Daniel E Morse
- Department of Molecular, Cellular and Developmental Biology and the Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California 93106-5100
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Levenson R, Bracken C, Bush N, Morse DE. Cyclable Condensation and Hierarchical Assembly of Metastable Reflectin Proteins, the Drivers of Tunable Biophotonics. J Biol Chem 2015; 291:4058-68. [PMID: 26719342 DOI: 10.1074/jbc.m115.686014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Indexed: 01/05/2023] Open
Abstract
Reversible changes in the phosphorylation of reflectin proteins have been shown to drive the tunability of color and brightness of light reflected from specialized cells in the skin of squids and related cephalopods. We show here, using dynamic light scattering, electron microscopy, and fluorescence analyses, that reversible titration of the excess positive charges of the reflectins, comparable with that produced by phosphorylation, is sufficient to drive the reversible condensation and hierarchical assembly of these proteins. The results suggest a two-stage process in which charge neutralization first triggers condensation, resulting in the emergence of previously cryptic structures that subsequently mediate reversible, hierarchical assembly. The extent to which cyclability is seen in the in vitro formation and disassembly of complexes estimated to contain several thousand reflectin molecules suggests that intrinsic sequence- and structure-determined specificity governs the reversible condensation and assembly of the reflectins and that these processes are therefore sufficient to produce the reversible changes in refractive index, thickness, and spacing of the reflectin-containing subcellular Bragg lamellae to change the brightness and color of reflected light. This molecular mechanism points to the metastability of reflectins as the centrally important design principle governing biophotonic tunability in this system.
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Affiliation(s)
- Robert Levenson
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106-5100
| | - Colton Bracken
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106-5100
| | - Nicole Bush
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106-5100
| | - Daniel E Morse
- From the Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106-5100
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