Structures, Organization, and Function of Reflectin Proteins in Dynamically Tunable Reflective Cells

DeMartini, Daniel G.; Izumi, Michi; Weaver, Aaron T.; Pandolfi, Erica C.; Morse, Daniel E.

doi:10.1074/jbc.m115.638254

Cited by 55 publications

(110 citation statements)

References 41 publications

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“…In these latter two species, the reflectins constitute the principal constituents of the dynamically controlled subcellular Bragg reflector lamellae responsible for the tunable color and intensity of reflected light in "iridocyte" cells (8) and the subcellular vesicles responsible for switchable bright white Mie scattering in specialized "leucophore" cells in females of the Pacific species (the only example, to our knowledge, of switchable broadband reflectance in molluscs) (6). Reflectins are also found, although in a different molar ratio, in the static (nontunable) Bragg lamellae of fixed-color iridocytes in this species (7).…”

mentioning

confidence: 91%

“…Plasmids were transformed into Rosetta 2 (DE3) cells and plated onto agarose plates con- (7,8). The GMXX motif in reflectin C is a unique region of increased overall hydrophobicity composed of a four-amino acid repeat, where X represents less conserved locations within the repeat (7). Additionally, the reflectin motif of reflectin C is marked with an asterisk to indicate that it contains substantial deviations in sequence not observed in any other reflectin motifs.…”

Section: Methodsmentioning

confidence: 99%

“…Protein expression and purification followed methods published previously (16). Plasmids were transformed into Rosetta 2 (DE3) cells and plated onto agarose plates con- (7,8). The GMXX motif in reflectin C is a unique region of increased overall hydrophobicity composed of a four-amino acid repeat, where X represents less conserved locations within the repeat (7).…”

Section: Methodsmentioning

confidence: 99%

“…Inhibition of this ACh-activated phosphorylation has been shown to block the ACh-activated changes in iridescence, establishing the requirement for phosphorylation (8). The four reflectins isolated from iridocytes in the non-reflective state have been found to be highly positively charged (computed pI values range from 8.6 -8.9), with addition of the negative charges upon phosphorylation essentially neutralizing the proteins (7,8). We hypothesized that the reflectins are therefore in a state of Coulombic repulsion in the non-reflective state, with phosphorylation overcoming this repulsion, allowing the reflectins to condense and assemble.…”

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confidence: 99%

“…In the tunable iridocytes, it has been shown that the action of ACh is mediated by a muscarinic ACh receptor (9) that, in turn, activates a G protein-phospholipase-Ca 2ϩ -calmodulin-mediated signal transduction cascade. This cascade culminates in the activation of specific protein kinases (and phosphatases) to dramatically change the pattern of phosphorylation of the four different reflectins located in the Bragg lamellae (7,8,11). Inhibition of this ACh-activated phosphorylation has been shown to block the ACh-activated changes in iridescence, establishing the requirement for phosphorylation (8).…”

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confidence: 99%

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Cyclable Condensation and Hierarchical Assembly of Metastable Reflectin Proteins, the Drivers of Tunable Biophotonics

Levenson

Bracken

Bush

et al. 2016

Journal of Biological Chemistry

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138

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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. Cephalopods (squids, octopi, and cuttlefish) are well known for their diversity of light-manipulating, pigment-based, and nano-structural systems used for camouflage and underwater communication (1, 2). Of these systems, the dynamically tunable structural color of certain squids holds great interest as models for next-generation tunable optical materials and devices (3, 4). Reflectins are a class of proteins originally identified in the reflective tissue of the Hawaiian bobtail squid, Euprymna scolopes (5), and have since been found in multiple squid species, including the pelagic Pacific and Atlantic squids Doryteuthis opalescens and Doryteuthis pealeii, respectively (6 -8). In these latter two species, the reflectins constitute the principal constituents of the dynamically controlled subcellular Bragg reflector lamellae responsible for the tunable color and intensity of reflected light in "iridocyte" cells (8) and the subcellular vesicles responsible for switchable bright white Mie scattering in specialized "leucophore" cells in females of the Pacific species (the only example, to our knowledge, of switchable broadband reflectance in molluscs) (6). Reflectins are also found, although in a different molar ratio, in the static (nontunable) Bragg lamellae of fixed-color iridocytes in this species (7).Reflectance from both the tunable iridocytes and switchable leucophores is activated by the diffusion of acetylcholine (ACh) 2 (8, 9), recently discovered to be released from fine neuronal processes innervating local areas of the squid skin (10). In the tunable iridocytes, it has been shown that the act...

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mentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Cyclable Condensation and Hierarchical Assembly of Metastable Reflectin Proteins, the Drivers of Tunable Biophotonics

Levenson

Bracken

Bush

et al. 2016

Journal of Biological Chemistry

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138

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Morphological and Physiological Colour Changes in the Animal Kingdom

Figon

Casas

2018

Encyclopedia of Life Sciences

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Colour change is the ability of an organism to modify its colouration in response to specific stimuli. Several biological functions have been proposed to explain colour changes, including ultraviolet (UV) protection, thermoregulation, crypsis, inter‐ and intraspecific communication. Changes in body colouration are mainly performed through two types of mechanisms referred to as morphological and physiological. Mechanistically, these two types of colour changes differ in their speed and the way coloured structures are altered. The proximal causes of these colour changes are identified in a handful number of species and demonstrate that common physiological, cellular and molecular actors are at play. However, the reasons why both colour‐change types are widespread in the animal kingdom and how they have evolved are still unknown. This is partly due to a lack of knowledge about the fitness implications of colour changes, particularly their energetic costs. Key Concepts Morphological and physiological colour changes are widespread in the animal kingdom. It has been suggested that both types of colour changes have the same biological functions, which are UV protection, thermoregulation, crypsis, inter‐ and intraspecific communication. Despite differences in speed and mechanisms, similar cellular and molecular actors are at play for both types of colour changes. Colour changes are triggered by environmental stimuli, mainly light, and are regulated by the neuronal and hormonal systems. The evolution of colour‐changing abilities is still poorly understood because the consequences of colour changes on individual fitness remain to be investigated.

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DNA‐Engineered Hydrogels with Light‐Adaptive Plasmonic Responses

Ryssy

Lehtonen

Loo

et al. 2022

Adv Funct Materials

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Orientational control of anisotropic plasmonic nanoparticles is an attractive proposition to generate dynamic plasmonic responses. Particularly, the use of light as a stimulus to modulate the orientation is extremely useful owing to its spatiotemporal operative ability. This work showcases a light-mediated approach to tune the orientational features of gold nanorods in DNAengineered hydrogel materials. The strategy relies on the use of visible-lightinduced photothermal effects to cause deformation of the hydrogel matrix, resulting in temperature-controlled polarization-dependent optical responses whose anisotropy features are highly adaptive to the nature of DNA crosslinks. The visible-light-mediated approach showcased here can open novel avenues to create dynamic light-responsive materials with reconfigurable plasmonic responses.

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Structures, Organization, and Function of Reflectin Proteins in Dynamically Tunable Reflective Cells

Cited by 55 publications

References 41 publications

Cyclable Condensation and Hierarchical Assembly of Metastable Reflectin Proteins, the Drivers of Tunable Biophotonics

Cyclable Condensation and Hierarchical Assembly of Metastable Reflectin Proteins, the Drivers of Tunable Biophotonics

Morphological and Physiological Colour Changes in the Animal Kingdom

DNA‐Engineered Hydrogels with Light‐Adaptive Plasmonic Responses

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