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Zarowny L, Clavel D, Johannson R, Duarte K, Depernet H, Dupuy J, Baker H, Brown A, Royant A, Campbell RE. Cyan fluorescent proteins derived from mNeonGreen. Protein Eng Des Sel 2022; 35:gzac004. [PMID: 35417013 PMCID: PMC9083105 DOI: 10.1093/protein/gzac004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 03/17/2022] [Accepted: 04/05/2022] [Indexed: 11/13/2022] Open
Abstract
mNeonGreen, an engineered green fluorescent protein (GFP) derived from lancelet, is one of the most brightly fluorescent homologs of Aequorea victoria jellyfish GFP (avGFP) yet reported. In this work, we investigated whether this bright fluorescence might be retained in homologs of mNeonGreen with modified chromophore structures and altered fluorescent hues. We found mNeonGreen to be generally less tolerant than avGFP to chromophore modification by substitution of the key chromophore-forming tyrosine residue with other aromatic amino acids. However, we were ultimately successful in creating a variant, designated as NeonCyan1, with a tryptophan-derived cyan fluorescent protein (CFP)-type chromophore, and two additional mutants with distinct spectral hues. Structural, computational, and photophysical characterization of NeonCyan1 and its variants provided insight into the factors that control the fluorescence emission color. Though not recommended as replacements for contemporary CFP variants, we demonstrate that NeonCyan1 variants are potentially suitable for live cell imaging applications.
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Affiliation(s)
- Landon Zarowny
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
| | - Damien Clavel
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Ryan Johannson
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
| | - Kévin Duarte
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Hadrien Depernet
- Structural Biology Group, European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Jérôme Dupuy
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
| | - Heather Baker
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
| | - Alex Brown
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
| | - Antoine Royant
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS), 38000 Grenoble, France
- Structural Biology Group, European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - Robert E Campbell
- Department of Chemistry, University of Alberta, Edmonton T6G 2G2, Canada
- Department of Chemistry, University of Tokyo, Tokyo 113-0033, Japan
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Gotthard G, von Stetten D, Clavel D, Noirclerc-Savoye M, Royant A. Chromophore Isomer Stabilization Is Critical to the Efficient Fluorescence of Cyan Fluorescent Proteins. Biochemistry 2017; 56:6418-6422. [PMID: 29148725 DOI: 10.1021/acs.biochem.7b01088] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
ECFP, the first usable cyan fluorescent protein (CFP), was obtained by adapting the tyrosine-based chromophore environment in green fluorescent protein to that of a tryptophan-based one. This first-generation CFP was superseded by the popular Cerulean, CyPet, and SCFP3A that were engineered by rational and random mutagenesis, yet the latter CFPs still exhibit suboptimal properties of pH sensitivity and reversible photobleaching behavior. These flaws were serendipitously corrected in the third-generation CFP mTurquoise and its successors without an obvious rationale. We show here that the evolution process had unexpectedly remodeled the chromophore environment in second-generation CFPs so they would accommodate a different isomer, whose formation is favored by acidic pH or light irradiation and which emits fluorescence much less efficiently. Our results illustrate how fluorescent protein engineering based solely on fluorescence efficiency optimization may affect other photophysical or physicochemical parameters and provide novel insights into the rational evolution of fluorescent proteins with a tryptophan-based chromophore.
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Affiliation(s)
| | | | - Damien Clavel
- Univ. Grenoble Alpes, CNRS, CEA, IBS (Institut de Biologie Structurale), F-38000 Grenoble, France
| | | | - Antoine Royant
- European Synchrotron Radiation Facility , F-38043 Grenoble, France.,Univ. Grenoble Alpes, CNRS, CEA, IBS (Institut de Biologie Structurale), F-38000 Grenoble, France
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