1
|
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] [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.
Collapse
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
| |
Collapse
|
2
|
Masquelier E, Taxon E, Liang SP, Al Sabeh Y, Sepunaru L, Gordon MJ, Morse DE. A new electrochemical method that mimics phosphorylation of the core tau peptide K18 enables kinetic and structural analysis of intermediates and assembly. J Biol Chem 2023; 299:103011. [PMID: 36781124 PMCID: PMC10024187 DOI: 10.1016/j.jbc.2023.103011] [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: 08/30/2022] [Revised: 02/04/2023] [Accepted: 02/08/2023] [Indexed: 02/13/2023] Open
Abstract
Tau protein's reversible assembly and binding of microtubules in brain neurons are regulated by charge-neutralizing phosphorylation, while its hyperphosphorylation drives the irreversible formation of cytotoxic filaments associated with neurodegenerative diseases. However, the structural changes that facilitate these diverse functions are unclear. Here, we analyzed K18, a core peptide of tau, using newly developed spectroelectrochemical instrumentation that enables electroreduction as a surrogate for charge neutralization by phosphorylation, with simultaneous, real-time quantitative analyses of the resulting conformational transitions and assembly. We observed a tipping point between behaviors that paralleled the transition between tau's physiologically required, reversible folding and assembly and the irreversibility of assemblies. The resulting rapidly electroassembled structures represent the first fibrillar tangles of K18 that have been formed in vitro at room temperature without using heparin or other charge-complementary anionic partners. These methods make it possible to (i) trigger and analyze in real time the early stages of conformational transitions and assembly without the need for preformed seeds, heterogenous coacervation, or crowding; (ii) kinetically resolve and potentially isolate never-before-seen early intermediates in these processes; and (iii) develop assays for additional factors and mechanisms that can direct the trajectory of assembly from physiologically benign and reversible to potentially pathological and irreversible structures. We anticipate wide applicability of these methods to other amyloidogenic systems and beyond.
Collapse
Affiliation(s)
- Eloise Masquelier
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California, USA; Materials Department, University of California, Santa Barbara, California, USA
| | - Esther Taxon
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California, USA; Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Sheng-Ping Liang
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California, USA; Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA
| | - Yahya Al Sabeh
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California, USA; Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA
| | - Michael J Gordon
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California, USA; Department of Chemical Engineering, University of California, Santa Barbara, California, USA
| | - Daniel E Morse
- Institute for Collaborative Biotechnologies, University of California, Santa Barbara, California, USA; Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA.
| |
Collapse
|
3
|
Song J, Liu C, Li B, Liu L, Zeng L, Ye Z, Wu W, Zhu L, Hu B. Synthetic peptides for the precise transportation of proteins of interests to selectable subcellular areas. Front Bioeng Biotechnol 2023; 11:1062769. [PMID: 36890909 PMCID: PMC9986269 DOI: 10.3389/fbioe.2023.1062769] [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: 10/06/2022] [Accepted: 02/09/2023] [Indexed: 02/22/2023] Open
Abstract
Proteins, as gifts from nature, provide structure, sequence, and function templates for designing biomaterials. As first reported here, one group of proteins called reflectins and derived peptides were found to present distinct intracellular distribution preferences. Taking their conserved motifs and flexible linkers as Lego bricks, a series of reflectin-derivates were designed and expressed in cells. The selective intracellular localization property leaned on an RMs (canonical conserved reflectin motifs)-replication-determined manner, suggesting that these linkers and motifs were constructional fragments and ready-to-use building blocks for synthetic design and construction. A precise spatiotemporal application demo was constructed in the work by integrating RLNto2 (as one representative of a synthetic peptide derived from RfA1) into the Tet-on system to effectively transport cargo peptides into nuclei at selective time points. Further, the intracellular localization of RfA1 derivatives was spatiotemporally controllable with a CRY2/CIB1 system. At last, the functional homogeneities of either motifs or linkers were verified, which made them standardized building blocks for synthetic biology. In summary, the work provides a modularized, orthotropic, and well-characterized synthetic-peptide warehouse for precisely regulating the nucleocytoplasmic localization of proteins.
Collapse
Affiliation(s)
- Junyi Song
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Chuanyang Liu
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Baoshan Li
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Liangcheng Liu
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Ling Zeng
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Zonghuang Ye
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Wenjian Wu
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Lingyun Zhu
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| | - Biru Hu
- Department of Biology and Chemistry, College of Science, National University of Defense Technology, Changsha, Hunan, China
| |
Collapse
|
4
|
Song J, Li B, Zeng L, Ye Z, Wu W, Hu B. A Mini-Review on Reflectins, from Biochemical Properties to Bio-Inspired Applications. Int J Mol Sci 2022; 23:ijms232415679. [PMID: 36555320 PMCID: PMC9779258 DOI: 10.3390/ijms232415679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 11/23/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022] Open
Abstract
Some cephalopods (squids, octopuses, and cuttlefishes) produce dynamic structural colors, for camouflage or communication. The key to this remarkable capability is one group of specialized cells called iridocytes, which contain aligned membrane-enclosed platelets of high-reflective reflectins and work as intracellular Bragg reflectors. These reflectins have unusual amino acid compositions and sequential properties, which endows them with functional characteristics: an extremely high reflective index among natural proteins and the ability to answer various environmental stimuli. Based on their unique material composition and responsive self-organization properties, the material community has developed an impressive array of reflectin- or iridocyte-inspired optical systems with distinct tunable reflectance according to a series of internal and external factors. More recently, scientists have made creative attempts to engineer mammalian cells to explore the function potentials of reflectin proteins as well as their working mechanism in the cellular environment. Progress in wide scientific areas (biophysics, genomics, gene editing, etc.) brings in new opportunities to better understand reflectins and new approaches to fully utilize them. The work introduced the composition features, biochemical properties, the latest developments, future considerations of reflectins, and their inspiration applications to give newcomers a comprehensive understanding and mutually exchanged knowledge from different communities (e.g., biology and material).
Collapse
Affiliation(s)
- Junyi Song
- Correspondence: (J.S.); (B.H.); Tel.: +86-18969697729 (J.S.); +86-13308492461 (B.H.)
| | | | | | | | | | - Biru Hu
- Correspondence: (J.S.); (B.H.); Tel.: +86-18969697729 (J.S.); +86-13308492461 (B.H.)
| |
Collapse
|
5
|
Song J, Liu C, Li B, Liu L, Zeng L, Ye Z, Mao T, Wu W, Hu B. Tunable Cellular Localization and Extensive Cytoskeleton-Interplay of Reflectins. Front Cell Dev Biol 2022; 10:862011. [PMID: 35813206 PMCID: PMC9259870 DOI: 10.3389/fcell.2022.862011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
Reflectin proteins are natural copolymers consisting of repeated canonical domains. They are located in a biophotonic system called Bragg lamellae and manipulate the dynamic structural coloration of iridocytes. Their biological functions are intriguing, but the underlying mechanism is not fully understood. Reflectin A1, A2, B1, and C were found to present distinguished cyto-/nucleoplasmic localization preferences in the work. Comparable intracellular localization was reproduced by truncated reflectin variants, suggesting a conceivable evolutionary order among reflectin proteins. The size-dependent access of reflectin variants into the nucleus demonstrated a potential model of how reflectins get into Bragg lamellae. Moreover, RfA1 was found to extensively interact with the cytoskeleton, including its binding to actin and enrichment at the microtubule organizing center. This implied that the cytoskeleton system plays a fundamental role during the organization and transportation of reflectin proteins. The findings presented here provide evidence to get an in-depth insight into the evolutionary processes and working mechanisms of reflectins, as well as novel molecular tools to achieve tunable intracellular transportation.
Collapse
Affiliation(s)
- Junyi Song
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
- *Correspondence: Junyi Song, ; Biru Hu,
| | - Chuanyang Liu
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
| | - Baoshan Li
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
| | - Liangcheng Liu
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
| | - Ling Zeng
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
| | - Zonghuang Ye
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
| | - Ting Mao
- Logistics Center, National University of Defense Technology, Changsha, China
| | - Wenjian Wu
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
| | - Biru Hu
- College of Liberal Arts Science, National University of Defense Technology, Changsha, China
- *Correspondence: Junyi Song, ; Biru Hu,
| |
Collapse
|
6
|
Liang SP, Masquelier E, Morse DE, Gordon MJ, Sepunaru L. Low Voltage Voltammetry Probes Proton Dissociation Equilibria of Amino Acids and Peptides. Anal Chem 2022; 94:4948-4953. [PMID: 35290024 DOI: 10.1021/acs.analchem.1c03371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Platinum-catalyzed electrochemical reduction of dissociable protons at low potentials was used to investigate proton dissociation equilibria of freely diffusing and peptide-incorporated charged amino acids. We first demonstrate with five charged essential amino acids and their analogs that the electrochemically induced deprotonation of each amino acid occurs at distinct formal reduction potential. Moreover, the observed direct reduction for all the charged species, excluding arginine, occurs at low potentials suitable for investigation under aqueous conditions (-0.4 to -0.9 V vs Ag/AgCl). The direct proton reduction was resolved via deconvolution of the observed differential pulse voltammogram (DPV) from background hydronium reduction and water electrolysis. A linear correlation was found between the formal reduction potentials and the pKa values of the dissociable protons hosted by various molecular moieties in the amino acids and their analogs and further verified with tripeptides. DPV of poly(l-lysine) decamer (Lys10) distinctively resolved the pKa values of the amino groups in the side chains and N-terminus, at a resolution not possible by conventional acid-base titration. This work demonstrates selective electrochemical titration of dissociable protons in charged amino acids in the free state and as residues in biomolecules, as well as the utility of DPV to indirectly interrogate local electrostatic environments that are essential to the stability and function of biomolecules.
Collapse
Affiliation(s)
- Sheng-Ping Liang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Eloise Masquelier
- Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Daniel E Morse
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, United States.,Institute of Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Michael J Gordon
- Institute of Collaborative Biotechnologies, University of California, Santa Barbara, Santa Barbara, California 93106, United States.,Department of Chemical Engineering, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States
| |
Collapse
|
7
|
Hossain MS, Ji J, Lynch CJ, Guzman M, Nangia S, Mozhdehi D. Adaptive Recombinant Nanoworms from Genetically Encodable Star Amphiphiles. Biomacromolecules 2021; 23:863-876. [PMID: 34942072 PMCID: PMC8924867 DOI: 10.1021/acs.biomac.1c01314] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recombinant nanoworms are promising candidates for materials and biomedical applications ranging from the templated synthesis of nanomaterials to multivalent display of bioactive peptides and targeted delivery of theranostic agents. However, molecular design principles to synthesize these assemblies (which are thermodynamically favorable only in a narrow region of the phase diagram) remain unclear. To advance the identification of design principles for the programmable assembly of proteins into well-defined nanoworms and to broaden their stability regimes, we were inspired by the ability of topologically engineered synthetic macromolecules to acess rare mesophases. To test this design principle in biomacromolecular assemblies, we used post-translational modifications (PTMs) to generate lipidated proteins with precise topological and compositional asymmetry. Using an integrated experimental and computational approach, we show that the material properties (thermoresponse and nanoscale assembly) of these hybrid amphiphiles are modulated by their amphiphilic architecture. Importantly, we demonstrate that the judicious choice of amphiphilic architecture can be used to program the assembly of proteins into adaptive nanoworms, which undergo a morphological transition (sphere-to-nanoworms) in response to temperature stimuli.
Collapse
Affiliation(s)
- Md Shahadat Hossain
- Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, 111 College Place, Syracuse, New York 13244, United States
| | - Jingjing Ji
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, New York 13244, United States
| | - Christopher J Lynch
- Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, 111 College Place, Syracuse, New York 13244, United States
| | - Miguel Guzman
- Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, 111 College Place, Syracuse, New York 13244, United States
| | - Shikha Nangia
- Department of Biomedical and Chemical Engineering, Syracuse University, 329 Link Hall, Syracuse, New York 13244, United States.,BioInspired Syracuse: Institute for Material and Living Systems, Syracuse University, Syracuse, New York 13244, United States
| | - Davoud Mozhdehi
- Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, 111 College Place, Syracuse, New York 13244, United States.,BioInspired Syracuse: Institute for Material and Living Systems, Syracuse University, Syracuse, New York 13244, United States
| |
Collapse
|
8
|
Masquelier E, Liang SP, Sepunaru L, Morse DE, Gordon MJ. Reversible electrochemical triggering and optical interrogation of polylysine α-helix formation. Bioelectrochemistry 2021; 144:108007. [PMID: 34871847 DOI: 10.1016/j.bioelechem.2021.108007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 11/30/2022]
Abstract
Reversible electrochemical triggering of the random coil to α-helix conformational transition of polylysine (Lys10, Lys20, Lys50) was accomplished at a Pt electrode at potentials < |1| V vs. Ag/AgCl. Direct electroreduction of the N-terminus vs ε-amino groups in Lys sidechains, as well as hydronium reduction and electrolysis, could be easily distinguished and deconvolved using differential pulse voltammetry. Electrochemistry was coupled with in situ UV absorbance and circular dichroism spectroscopies to dynamically follow the evolution of α-helix formation at different potentials. Isotope experiments in H2O vs. D2O unequivocally confirm that direct electroreduction of ε-NH3+/ND3+ groups in Lys sidechains, rather than electrochemically generated pH gradient-induced deprotonation, leads to subsequent α-helix formation. The site-selective electrochemistry and optical methodologies presented herein can be generalized and extended to interrogate other protonation-sensitive biomolecular systems, and potentially provide access to early intermediates and control over the dynamic structural evolution of peptides and proteins.
Collapse
Affiliation(s)
- Eloise Masquelier
- Materials Department, University of California, Santa Barbara, CA, United States
| | - Sheng-Ping Liang
- Dept. Of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States
| | - Lior Sepunaru
- Dept. Of Chemistry and Biochemistry, University of California, Santa Barbara, CA, United States
| | - Daniel E Morse
- Dept. Of Molecular, Cellular and Development Biology, University of California, Santa Barbara, CA, United States; Institue for Collaborative Biotechnologies, University of California, Santa Barbara, CA, United States
| | - Michael J Gordon
- Dept. Of Chemical Engineering, University of California, Santa Barbara, CA, United States; Institue for Collaborative Biotechnologies, University of California, Santa Barbara, CA, United States.
| |
Collapse
|
9
|
Shamilov R, Robinson VL, Aneskievich BJ. Seeing Keratinocyte Proteins through the Looking Glass of Intrinsic Disorder. Int J Mol Sci 2021; 22:ijms22157912. [PMID: 34360678 PMCID: PMC8348711 DOI: 10.3390/ijms22157912] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/28/2021] [Accepted: 07/20/2021] [Indexed: 02/06/2023] Open
Abstract
Epidermal keratinocyte proteins include many with an eccentric amino acid content (compositional bias), atypical ultrastructural fate (built-in protease sensitivity), or assembly visible at the light microscope level (cytoplasmic granules). However, when considered through the looking glass of intrinsic disorder (ID), these apparent oddities seem quite expected. Keratinocyte proteins with highly repetitive motifs are of low complexity but high adaptation, providing polymers (e.g., profilaggrin) for proteolysis into bioactive derivatives, or monomers (e.g., loricrin) repeatedly cross-linked to self and other proteins to shield underlying tissue. Keratohyalin granules developing from liquid–liquid phase separation (LLPS) show that unique biomolecular condensates (BMC) and proteinaceous membraneless organelles (PMLO) occur in these highly customized cells. We conducted bioinformatic and in silico assessments of representative keratinocyte differentiation-dependent proteins. This was conducted in the context of them having demonstrated potential ID with the prospect of that characteristic driving formation of distinctive keratinocyte structures. Intriguingly, while ID is characteristic of many of these proteins, it does not appear to guarantee LLPS, nor is it required for incorporation into certain keratinocyte protein condensates. Further examination of keratinocyte-specific proteins will provide variations in the theme of PMLO, possibly recognizing new BMC for advancements in understanding intrinsically disordered proteins as reflected by keratinocyte biology.
Collapse
Affiliation(s)
- Rambon Shamilov
- Graduate Program in Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Connecticut, 69 North Eagleville Road, Storrs, CT 06269, USA;
| | - Victoria L. Robinson
- Department of Molecular and Cellular Biology, College of Liberal Arts & Sciences, University of Connecticut, 91 North Eagleville Road, Storrs, CT 06269, USA;
| | - Brian J. Aneskievich
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut, Storrs, CT 06269, USA
- Correspondence: ; Tel.: +1-860-486-3053
| |
Collapse
|
10
|
Wolde-Michael E, Roberts AD, Heyes DJ, Dumanli AG, Blaker JJ, Takano E, Scrutton NS. Design and fabrication of recombinant reflectin-based multilayer reflectors: bio-design engineering and photoisomerism induced wavelength modulation. Sci Rep 2021; 11:14580. [PMID: 34272457 PMCID: PMC8285536 DOI: 10.1038/s41598-021-94042-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/18/2021] [Indexed: 11/08/2022] Open
Abstract
The remarkable camouflage capabilities of cephalopods have inspired many to develop dynamic optical materials which exploit certain design principles and/or material properties from cephalopod dermal cells. Here, the angle-dependent optical properties of various single-layer reflectin thin-films on Si wafers are characterized within the UV-Vis-NIR regions. Following this, initial efforts to design, fabricate, and optically characterize a bio-inspired reflectin-based multilayer reflector is described, which was found to conserve the optical properties of single layer films but exhibit reduced angle-dependent visible reflectivity. Finally, we report the integration of phytochrome visible light-induced isomerism into reflectin-based films, which was found to subtly modulate reflectin thin-film reflectivity.
Collapse
Affiliation(s)
- Emmanuel Wolde-Michael
- Department of Chemistry, EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, UK
| | - Aled D Roberts
- Department of Chemistry, EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, UK
| | - Derren J Heyes
- Department of Chemistry, EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, UK
| | - Ahu G Dumanli
- Department of Materials and Henry Royce Institute, The University of Manchester, Manchester, M13 9PL, UK
| | - Jonny J Blaker
- Department of Materials and Henry Royce Institute, The University of Manchester, Manchester, M13 9PL, UK
| | - Eriko Takano
- Department of Chemistry, EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, UK
| | - Nigel S Scrutton
- Department of Chemistry, EPSRC/BBSRC Future Biomanufacturing Research Hub, Manchester Institute of Biotechnology, The University of Manchester, Manchester, M1 7DN, UK.
| |
Collapse
|
11
|
Deravi LF. Compositional similarities that link the eyes and skin of cephalopods: Implications in optical sensing and signaling during camouflage. Integr Comp Biol 2021; 61:1511-1516. [PMID: 34160621 DOI: 10.1093/icb/icab143] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cephalopods, including squid, octopus, and cuttlefish, can rapidly camouflage in different underwater environments by employing multiple optical effects including light scattering, absorption, reflection, and refraction. They can do so with exquisite control and within a fraction of a second-two features that indicate distributed, intra-dermal sensory and signaling components. However, the fundamental biochemical, electrical, and mechanical controls that regulate color and color change, from discrete elements to interconnected modules, are still not fully understood despite decades of research in this space. This perspective highlights key advancements in the biochemical analysis of cephalopod skin and discusses compositional connections between cephalopod ocular lenses and skin with features that may also facilitate signal transduction during camouflage.
Collapse
Affiliation(s)
- Leila F Deravi
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, 102 Hurtig Hall, 360 Huntington Ave, Boston, MA 02115
| |
Collapse
|
12
|
Tan J, Zhang L, Hsieh MC, Goodwin JT, Grover MA, Lynn DG. Chemical control of peptide material phase transitions. Chem Sci 2021; 12:3025-3031. [PMID: 34164071 PMCID: PMC8179288 DOI: 10.1039/d0sc03666h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Progressive solute-rich polymer phase transitions provide pathways for achieving ordered supramolecular assemblies. Intrinsically disordered protein domains specifically regulate information in biological networks via conformational ordering. Here we consider a molecular tagging strategy to control ordering transitions in polymeric materials and provide a proof-of-principle minimal peptide phase network captured with a dynamic chemical network. Substrate initiated assembly of a dynamic chemical network.![]()
Collapse
Affiliation(s)
- Junjun Tan
- Department of Chemistry and Biology, Emory University Atlanta Georgia 30322 USA
| | - Li Zhang
- Department of Chemistry and Biology, Emory University Atlanta Georgia 30322 USA
| | - Ming-Chien Hsieh
- Department of Chemistry and Biology, Emory University Atlanta Georgia 30322 USA .,School of Chemical and Biomolecular Engineering, Georgia Institute of Technology Atlanta Georgia 30332 USA
| | - Jay T Goodwin
- Department of Chemistry and Biology, Emory University Atlanta Georgia 30322 USA
| | - Martha A Grover
- School of Chemical and Biomolecular Engineering, Georgia Institute of Technology Atlanta Georgia 30332 USA
| | - David G Lynn
- Department of Chemistry and Biology, Emory University Atlanta Georgia 30322 USA
| |
Collapse
|
13
|
Umerani MJ, Pratakshya P, Chatterjee A, Cerna Sanchez JA, Kim HS, Ilc G, Kovačič M, Magnan C, Marmiroli B, Sartori B, Kwansa AL, Orins H, Bartlett AW, Leung EM, Feng Z, Naughton KL, Norton-Baker B, Phan L, Long J, Allevato A, Leal-Cruz JE, Lin Q, Baldi P, Bernstorff S, Plavec J, Yingling YG, Gorodetsky AA. Structure, self-assembly, and properties of a truncated reflectin variant. Proc Natl Acad Sci U S A 2020; 117:32891-32901. [PMID: 33323484 PMCID: PMC7780002 DOI: 10.1073/pnas.2009044117] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Naturally occurring and recombinant protein-based materials are frequently employed for the study of fundamental biological processes and are often leveraged for applications in areas as diverse as electronics, optics, bioengineering, medicine, and even fashion. Within this context, unique structural proteins known as reflectins have recently attracted substantial attention due to their key roles in the fascinating color-changing capabilities of cephalopods and their technological potential as biophotonic and bioelectronic materials. However, progress toward understanding reflectins has been hindered by their atypical aromatic and charged residue-enriched sequences, extreme sensitivities to subtle changes in environmental conditions, and well-known propensities for aggregation. Herein, we elucidate the structure of a reflectin variant at the molecular level, demonstrate a straightforward mechanical agitation-based methodology for controlling this variant's hierarchical assembly, and establish a direct correlation between the protein's structural characteristics and intrinsic optical properties. Altogether, our findings address multiple challenges associated with the development of reflectins as materials, furnish molecular-level insight into the mechanistic underpinnings of cephalopod skin cells' color-changing functionalities, and may inform new research directions across biochemistry, cellular biology, bioengineering, and optics.
Collapse
Affiliation(s)
- Mehran J. Umerani
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697
| | | | - Atrouli Chatterjee
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA 92697
| | - Juana A. Cerna Sanchez
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697
| | - Ho Shin Kim
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695
| | - Gregor Ilc
- Slovenian NMR Centre, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Matic Kovačič
- Slovenian NMR Centre, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Christophe Magnan
- Department of Computer Science, University of California, Irvine, CA 92697
| | - Benedetta Marmiroli
- Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria
| | - Barbara Sartori
- Institute of Inorganic Chemistry, Graz University of Technology, 8010 Graz, Austria
| | - Albert L. Kwansa
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695
| | - Helen Orins
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA 92697
| | - Andrew W. Bartlett
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA 92697
| | - Erica M. Leung
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA 92697
| | - Zhijing Feng
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697
| | - Kyle L. Naughton
- Department of Physics and Astronomy, University of California, Irvine, CA 92697
| | | | - Long Phan
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697
| | - James Long
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA 92697
| | - Alex Allevato
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697
| | - Jessica E. Leal-Cruz
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697
| | - Qiyin Lin
- Irvine Materials Research Institute, University of California, Irvine, CA 92697
| | - Pierre Baldi
- Department of Computer Science, University of California, Irvine, CA 92697
| | | | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Yaroslava G. Yingling
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695
| | - Alon A. Gorodetsky
- Department of Materials Science and Engineering, University of California, Irvine, CA 92697
- Department of Chemistry, University of California, Irvine, CA 92697
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, CA 92697
| |
Collapse
|
14
|
Liang SP, Levenson R, Malady B, Gordon MJ, Morse DE, Sepunaru L. Electrochemistry as a surrogate for protein phosphorylation: voltage-controlled assembly of reflectin A1. J R Soc Interface 2020; 17:20200774. [PMID: 33259748 DOI: 10.1098/rsif.2020.0774] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Phosphorylation is among the most widely distributed mechanisms regulating the tunable structure and function of proteins in response to neuronal, hormonal and environmental signals. We demonstrate here that the low-voltage electrochemical reduction of histidine residues in reflectin A1, a protein that mediates the neuronal fine-tuning of colour reflected from skin cells for camouflage and communication in squids, acts as an in vitro surrogate for phosphorylation in vivo, driving the assembly previously shown to regulate its function. Using micro-drop voltammetry and a newly designed electrochemical cell integrated with an instrument measuring dynamic light scattering, we demonstrate selective reduction of the imidazolium side chains of histidine in monomers, oligopeptides and this complex protein in solution. The formal reduction potential of imidazolium proves readily distinguishable from those of hydronium and primary amines, allowing unequivocal confirmation of the direct and energetically selective deprotonation of histidine in the protein. The resulting 'electro-assembly' provides a new approach to probe, understand, and control the mechanisms that dynamically tune protein structure and function in normal physiology and disease. With its abilities to serve as a surrogate for phosphorylation and other mechanisms of charge neutralization, and to potentially isolate early intermediates in protein assembly, this method may be useful for analysing never-before-seen early intermediates in the phosphorylation-driven assembly of other proteins in normal physiology and disease.
Collapse
Affiliation(s)
- Sheng-Ping Liang
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Building 232, Santa Barbara, CA 93106-9510, USA
| | - Robert Levenson
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA.,Soka University of America, Aliso Viejo, CA 92656, USA
| | - Brandon Malady
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA
| | - Michael J Gordon
- Department of Chemical Engineering, University of California, Santa Barbara, CA 93106-5080, USA.,Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106-5100, USA
| | - Daniel E Morse
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106-9625, USA.,Institute for Collaborative Biotechnologies, University of California, Santa Barbara, CA 93106-5100, USA
| | - Lior Sepunaru
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Building 232, Santa Barbara, CA 93106-9510, USA
| |
Collapse
|
15
|
Gough CR, Rivera-Galletti A, Cowan DA, Salas-de la Cruz D, Hu X. Protein and Polysaccharide-Based Fiber Materials Generated from Ionic Liquids: A Review. Molecules 2020; 25:E3362. [PMID: 32722182 PMCID: PMC7435976 DOI: 10.3390/molecules25153362] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/19/2020] [Accepted: 07/24/2020] [Indexed: 02/06/2023] Open
Abstract
Natural biomacromolecules such as structural proteins and polysaccharides are composed of the basic building blocks of life: amino acids and carbohydrates. Understanding their molecular structure, self-assembly and interaction in solvents such as ionic liquids (ILs) is critical for unleashing a flora of new materials, revolutionizing the way we fabricate multi-structural and multi-functional systems with tunable physicochemical properties. Ionic liquids are superior to organic solvents because they do not produce unwanted by-products and are considered green substitutes because of their reusability. In addition, they will significantly improve the miscibility of biopolymers with other materials while maintaining the mechanical properties of the biopolymer in the final product. Understanding and controlling the physicochemical properties of biopolymers in ionic liquids matrices will be crucial for progress leading to the ability to fabricate robust multi-level structural 1D fiber materials. It will also help to predict the relationship between fiber conformation and protein secondary structures or carbohydrate crystallinity, thus creating potential applications for cell growth signaling, ionic conductivity, liquid diffusion and thermal conductivity, and several applications in biomedicine and environmental science. This will also enable the regeneration of biopolymer composite fiber materials with useful functionalities and customizable options critical for additive manufacturing. The specific capabilities of these fiber materials have been shown to vary based on their fabrication methods including electrospinning and post-treatments. This review serves to provide basic knowledge of these commonly utilized protein and polysaccharide biopolymers and their fiber fabrication methods from various ionic liquids, as well as the effect of post-treatments on these fiber materials and their applications in biomedical and pharmaceutical research, wound healing, environmental filters and sustainable and green chemistry research.
Collapse
Affiliation(s)
- Christopher R. Gough
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA; (C.R.G.); (A.R.-G.); (D.A.C.)
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA
| | - Ashley Rivera-Galletti
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA; (C.R.G.); (A.R.-G.); (D.A.C.)
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA
| | - Darrel A. Cowan
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA; (C.R.G.); (A.R.-G.); (D.A.C.)
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA
| | - David Salas-de la Cruz
- Department of Chemistry, and Center for Computational and Integrative Biology, Camden, NJ 08102, USA;
| | - Xiao Hu
- Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, USA; (C.R.G.); (A.R.-G.); (D.A.C.)
- Department of Biomedical Engineering, Rowan University, Glassboro, NJ 08028, USA
- Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, NJ 08028, USA
| |
Collapse
|
16
|
Liquid-liquid phase separation in biology: mechanisms, physiological functions and human diseases. SCIENCE CHINA. LIFE SCIENCES 2020; 63:953-985. [PMID: 32548680 DOI: 10.1007/s11427-020-1702-x] [Citation(s) in RCA: 138] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/20/2020] [Indexed: 02/06/2023]
Abstract
Cells are compartmentalized by numerous membrane-enclosed organelles and membraneless compartments to ensure that a wide variety of cellular activities occur in a spatially and temporally controlled manner. The molecular mechanisms underlying the dynamics of membrane-bound organelles, such as their fusion and fission, vesicle-mediated trafficking and membrane contactmediated inter-organelle interactions, have been extensively characterized. However, the molecular details of the assembly and functions of membraneless compartments remain elusive. Mounting evidence has emerged recently that a large number of membraneless compartments, collectively called biomacromolecular condensates, are assembled via liquid-liquid phase separation (LLPS). Phase-separated condensates participate in various biological activities, including higher-order chromatin organization, gene expression, triage of misfolded or unwanted proteins for autophagic degradation, assembly of signaling clusters and actin- and microtubule-based cytoskeletal networks, asymmetric segregations of cell fate determinants and formation of pre- and post-synaptic density signaling assemblies. Biomacromolecular condensates can transition into different material states such as gel-like structures and solid aggregates. The material properties of condensates are crucial for fulfilment of their distinct functions, such as biochemical reaction centers, signaling hubs and supporting architectures. Cells have evolved multiple mechanisms to ensure that biomacromolecular condensates are assembled and disassembled in a tightly controlled manner. Aberrant phase separation and transition are causatively associated with a variety of human diseases such as neurodegenerative diseases and cancers. This review summarizes recent major progress in elucidating the roles of LLPS in various biological pathways and diseases.
Collapse
|
17
|
Song J, Levenson R, Santos J, Velazquez L, Zhang F, Fygenson D, Wu W, Morse DE. Reflectin Proteins Bind and Reorganize Synthetic Phospholipid Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:2673-2682. [PMID: 32097553 DOI: 10.1021/acs.langmuir.9b03632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The reflectin proteins have been extensively studied for their role in reflectance in cephalopods. In the recently evolved Loliginid squids, these proteins and the structural color they regulate are dynamically tunable, enhancing their effectiveness for camouflage and communication. In these species, the reflectins are found in highest concentrations within the structurally tunable, membrane enclosed, periodically stacked lamellae of subcellular Bragg reflectors and in the intracellular vesicles of specialized skin cells known as iridocytes and leuocophores, respectively. To better understand the interactions between the reflectins and the membrane structures that encompass them, we analyzed the interactions of two purified reflectins with synthetic phospholipid membrane vesicles similar in composition to cellular membranes, using confocal fluorescence microscopy and dynamic light scattering. The purified recombinant reflectins were found to drive multivalent vesicle agglomeration in a ratio-dependent and saturable manner. Extensive proteolytic digestion terminated with PMSF of the reflectin A1-vesicle complexes triggered energetic membrane rearrangement, resulting in vesicle fusion, fission, and tubulation. This behavior contrasted markedly with that of vesicles complexed with reflectin C, from which PMSF-terminated proteolysis only released the original size vesicles. Clues to the basis for this difference, residing in significant differences between the structures of the two reflectins, led to the suggestion that specific reflectin-membrane interactions may play a role in the ontogenetic formation, long-term maintenance, and/or dynamic behavior of their biophotonically active host membrane nanostructures. Similar energetic remodeling has been associated with osmotic stress in other membrane systems, suggesting a path to reconstitution of the biophotonic system in vitro.
Collapse
Affiliation(s)
- Junyi Song
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-5100, United States
| | - Robert Levenson
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-5100, United States
| | - Jerome Santos
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-5100, United States
| | - Lourdes Velazquez
- Physics Department and California Nanosystems Institute, University of California, Santa Barbara, California 93106, United States
| | - Fan Zhang
- College of Sciences, Nanjing Agricultural University, Nanjing 210095, PR China
| | - Deborah Fygenson
- Physics Department and California Nanosystems Institute, University of California, Santa Barbara, California 93106, United States
| | - Wenjian Wu
- College of Liberal Arts and Science, National University of Defense Technology, Changsha, Hunan 410073, China
| | - Daniel E Morse
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-5100, United States
| |
Collapse
|