Like GFP, the fluorescent protein DsRed has a chromophore that forms autocatalytically within the folded protein, but the mechanism of DsRed chromophore formation has been unclear. It was proposed that an initial oxidation generates a green chromophore, and that a final oxidation yields the red chromophore. However, this model does not adequately explain why a mature DsRed sample contains a mixture of green and red chromophores. We present evidence that the maturation pathway for DsRed branches upstream of chromophore formation. After an initial oxidation step, a final oxidation to form the acylimine of the red chromophore is in kinetic competition with a dehydration to form the green chromophore. This scheme explains why green and red chromophores are alternative end points of the maturation pathway.
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http://dx.doi.org/10.1021/ja1030084 | DOI Listing |
Nat Chem
January 2025
SAMS Research Group, Université de Strasbourg, CNRS, Institut Charles Sadron UPR 22, Strasbourg, France.
Molecular spin qubits have the advantages of synthetic flexibility and amenability to be tailored to specific applications. Among them, chromophore-radical systems have emerged as appealing qubit candidates. These systems can be initiated by light to form triplet-radical pairs that can result in the formation of quartet states by spin mixing.
View Article and Find Full Text PDFCurr Top Dev Biol
January 2025
Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH, United States. Electronic address:
Animals perceiving light through visual pigments have evolved pathways for absorbing, transporting, and metabolizing the precursors essential for synthesis of their retinylidene chromophores. Over the past decades, our understanding of this metabolism has grown significantly. Through genetic manipulation, researchers gained insights into the metabolic complexity of the pathways mediating the flow of chromophore precursors throughout the body, and their enrichment within the eyes.
View Article and Find Full Text PDFCurr Top Dev Biol
January 2025
Center for Translational Vision Research, Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, CA, United States; Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, United States; Department of Chemistry, University of California Irvine, Irvine, CA, United States; Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA, United States. Electronic address:
Vitamin A (all-trans-retinol; at-Rol) and its derivatives, known as retinoids, have been adopted by vertebrates to serve as visual chromophores and signaling molecules, particularly in the eye/retina. Few tissues rely on retinoids as heavily as the retina, and the study of genetically modified mouse models with deficiencies in specific retinoid-metabolizing proteins has allowed us to gain insight into the unique or redundant roles of these proteins in at-Rol uptake and storage, or their downstream roles in retinal development and function. These processes occur during embryogenesis and continue throughout life.
View Article and Find Full Text PDFOpen Biol
January 2025
Institute of Physical Chemistry, Polish Academy of Sciences , Warsaw, Poland.
The vertebrate visual cycle hinges on enzymatically converting all--retinol (at-ROL) into 11--retinal (11c-RAL), the chromophore that binds to opsins in photoreceptors, forming light-responsive pigments. When struck by a photon, these pigments activate the phototransduction pathway and initiate the process of vision. The enzymatic isomerization of at-ROL, crucial for restoring the visual pigments and preparing them to receive new light stimuli, relies on various enzymes found in both the photoreceptors and retinal pigment epithelium cells.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Max Planck Institute for Medical Research, Jahnstr. 29, Heidelberg 69120, Germany.
Orange carotenoid protein (OCP) is a photoactive protein that mediates photoprotection in cyanobacteria. OCP binds different ketocarotenoid chromophores such as echinenone (ECN), 3'- hydroxyechinenone (hECN), and canthaxanthin (CAN). In the dark, OCP is in an inactive orange form known as OCP; upon illumination, a red active state is formed, referred to as OCP, that can interact with the phycobilisome.
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