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Roger T. Hanlon - One of the best experts on this subject based on the ideXlab platform.
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visual phototransduction components in cephalopod Chromatophores suggest dermal photoreception
The Journal of Experimental Biology, 2015Co-Authors: Alexandra C N Kingston, Alan M. Kuzirian, Roger T. Hanlon, Thomas W CroninAbstract:ABSTRACT Cephalopod mollusks are renowned for their colorful and dynamic body patterns, produced by an assemblage of skin components that interact with light. These may include iridophores, leucophores, Chromatophores and (in some species) photophores. Here, we present molecular evidence suggesting that cephalopod Chromatophores – small dermal pigmentary organs that reflect various colors of light – are photosensitive. RT-PCR revealed the presence of transcripts encoding rhodopsin and retinochrome within the retinas and skin of the squid Doryteuthis pealeii , and the cuttlefish Sepia officinalis and Sepia latimanus . In D. pealeii , G qα and squid TRP channel transcripts were present in the retina and in all dermal samples. Rhodopsin, retinochrome and G qα transcripts were also found in RNA extracts from dissociated Chromatophores isolated from D. pealeii dermal tissues. Immunohistochemical staining labeled rhodopsin, retinochrome and G qα proteins in several chromatophore components, including pigment cell membranes, radial muscle fibers, and sheath cells. This is the first evidence that cephalopod dermal tissues, and specifically Chromatophores, may possess the requisite combination of molecules required to respond to light.
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progress towards elucidating the structure function relationships of a natural nanoscale photonic device in cuttlefish Chromatophores
Proceedings of SPIE, 2015Co-Authors: Leila F Deravi, Andrew P Magyar, Sean P Sheehy, George R R Bell, Alan M. Kuzirian, Lydia M. Mäthger, Roger T. Hanlon, Kevin Kit ParkerAbstract:The adaptive coloration observed in cuttlefish Sepia officinalis skin is facilitated in part by properties of pigmented Chromatophores that have not been previously reported. We found that chromatophore coloration is enabled by a tethering system that distributes layered pigment granules, comprised of fluorescent nanostructures, to optimize color intensity as the Chromatophores are actuated. The design features gleaned from these studies provide intriguing insights into the development of artificial photonic systems useful for products ranging from conformable, high-definition color displays to optical fabrics capable of adapting their coloration within an ambient environment.
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the structure function relationships of a natural nanoscale photonic device in cuttlefish Chromatophores
Journal of the Royal Society Interface, 2014Co-Authors: Leila F Deravi, Andrew P Magyar, Sean P Sheehy, George R R Bell, Stephen L. Senft, Alan M. Kuzirian, Lydia M. Mäthger, Trevor J. Wardill, William S Lane, Roger T. HanlonAbstract:Cuttlefish, Sepia officinalis, possess neurally controlled, pigmented chromatophore organs that allow rapid changes in skin patterning and coloration in response to visual cues. This process of adaptive coloration is enabled by the 500% change in chromatophore surface area during actuation. We report two adaptations that help to explain how colour intensity is maintained in a fully expanded chromatophore when the pigment granules are distributed maximally: (i) pigment layers as thin as three granules that maintain optical effectiveness and (ii) the presence of high-refractive-index proteins—reflectin and crystallin—in granules. The latter discovery, combined with our finding that isolated chromatophore pigment granules fluoresce between 650 and 720 nm, refutes the prevailing hypothesis that cephalopod Chromatophores are exclusively pigmentary organs composed solely of ommochromes. Perturbations to granular architecture alter optical properties, illustrating a role for nanostructure in the agile, optical responses of Chromatophores. Our results suggest that cephalopod chromatophore pigment granules are more complex than homogeneous clusters of chromogenic pigments. They are luminescent protein nanostructures that facilitate the rapid and sophisticated changes exhibited in dermal pigmentation.
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malleable skin coloration in cephalopods selective reflectance transmission and absorbance of light by Chromatophores and iridophores
Cell and Tissue Research, 2007Co-Authors: Lydia M. Mäthger, Roger T. HanlonAbstract:Nature’s best-known example of colorful, changeable, and diverse skin patterning is found in cephalopods. Color and pattern changes in squid skin are mediated by the action of thousands of pigmented chromatophore organs in combination with subjacent light-reflecting iridophore cells. Chromatophores (brown, red, yellow pigment) are innervated directly by the brain and can quickly expand and retract over underlying iridophore cells (red, orange, yellow, green, blue iridescence). Here, we present the first spectral account of the colors that are produced by the interaction between Chromatophores and iridophores in squid (Loligo pealeii). Using a spectrometer, we have acquired highly focused reflectance measurements of Chromatophores, iridophores, and the quality and quantity of light reflected when both interact. Results indicate that the light reflected from iridophores can be filtered by the Chromatophores, enhancing their appearance. We have also measured polarization aspects of iridophores and Chromatophores and show that, whereas structurally reflecting iridophores polarize light at certain angles, pigmentary Chromatophores do not. We have further measured the reflectance change that iridophores undergo during physiological activity, from “off” to various degrees of “on”, revealing specifically the way that colors shift from the longer end (infra-red and red) to the shorter (blue) end of the spectrum. By demonstrating that three color classes of pigments, combined with a single type of reflective cell, produce colors that envelop the whole of the visible spectrum, this study provides an insight into the optical mechanisms employed by the elaborate skin of cephalopods to give the extreme diversity that enables their dynamic camouflage and signaling.
Eva C M Nowack - One of the best experts on this subject based on the ideXlab platform.
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Massive Protein Import into the Early-Evolutionary-Stage Photosynthetic Organelle of the Amoeba Paulinella chromatophora
Current biology : CB, 2017Co-Authors: Anna Singer, Stefan A Rensing, Gereon Poschmann, Cornelia Mühlich, Cecilio Valadez-cano, Sebastian Hänsch, Vanessa Hüren, Kai Stühler, Eva C M NowackAbstract:The endosymbiotic acquisition of mitochondria and plastids more than 1 Ga ago profoundly impacted eukaryote evolution. At the heart of understanding organelle evolution is the re-arrangement of the endosymbiont proteome into a host-controlled organellar proteome. However, early stages in this process as well as the timing of events that underlie organelle integration remain poorly understood. The amoeba Paulinella chromatophora contains cyanobacterium-derived photosynthetic organelles, termed "Chromatophores," that were acquired more recently (around 100 Ma ago). To explore the re-arrangement of an organellar proteome during its integration into a eukaryotic host cell, here we characterized the chromatophore proteome by protein mass spectrometry. Apparently, genetic control over the chromatophore has shifted substantially to the nucleus. Two classes of nuclear-encoded proteins-which differ in protein length-are imported into the chromatophore, most likely through independent pathways. Long imported proteins carry a putative, conserved N-terminal targeting signal, and many specifically fill gaps in chromatophore-encoded metabolic pathways or processes. Surprisingly, upon heterologous expression in a plant cell, the putative chromatophore targeting signal conferred chloroplast localization. This finding suggests common features in the protein import pathways of Chromatophores and plastids, two organelles that evolved independently and more than 1 Ga apart from each other. By combining experimental data with in silico predictions, we provide a comprehensive catalog of almost 450 nuclear-encoded, chromatophore-targeted proteins. Interestingly, most imported proteins seem to derive from ancestral host genes, suggesting that the re-targeting of nuclear-encoded proteins that resulted from endosymbiotic gene transfers plays only a minor role at the onset of chromatophore integration.
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impact of light intensity and quality on chromatophore and nuclear gene expression in paulinella chromatophora an amoeba with nascent photosynthetic organelles
Plant Journal, 2017Co-Authors: Ru Zhang, Debashish Bhattacharya, Eva C M Nowack, Dana C Price, Arthur R GrossmanAbstract:Summary Plastid evolution has been attributed to a single primary endosymbiotic event that occurred about 1.6 billion years ago (BYA) in which a cyanobacterium was engulfed and retained by a eukaryotic cell, although early steps in plastid integration are poorly understood. The photosynthetic amoeba Paulinella chromatophora represents a unique model for the study of plastid evolution because it contains cyanobacterium-derived photosynthetic organelles termed ‘Chromatophores’ that originated relatively recently (0.09–0.14 BYA). The chromatophore genome is about a third the size of the genome of closely related cyanobacteria, but 10-fold larger than most plastid genomes. Several genes have been transferred from the chromatophore genome to the host nuclear genome through endosymbiotic gene transfer (EGT). Some EGT-derived proteins could be imported into Chromatophores for function. Two photosynthesis-related genes (psaI and csos4A) are encoded by both the nuclear and chromatophore genomes, suggesting that EGT in Paulinella chromatophora is ongoing. Many EGT-derived genes encode proteins that function in photosynthesis and photoprotection, including an expanded family of high-light-inducible (ncHLI) proteins. Cyanobacterial hli genes are high-light induced and required for cell viability under excess light. We examined the impact of light on Paulinella chromatophora and found that this organism is light sensitive and lacks light-induced transcriptional regulation of chromatophore genes and most EGT-derived nuclear genes. However, several ncHLI genes have reestablished light-dependent regulation, which appears analogous to what is observed in cyanobacteria. We postulate that expansion of the ncHLI gene family and its regulation may reflect the light/oxidative stress experienced by Paulinella chromatophora as a consequence of the as yet incomplete integration of host and chromatophore metabolisms.
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gene transfers from diverse bacteria compensate for reductive genome evolution in the chromatophore of paulinella chromatophora
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Eva C M Nowack, Debashish Bhattacharya, Dana C Price, Michael Melkonian, Anna Singer, Arthur R GrossmanAbstract:Abstract Plastids, the photosynthetic organelles, originated >1 billion y ago via the endosymbiosis of a cyanobacterium. The resulting proliferation of primary producers fundamentally changed global ecology. Endosymbiotic gene transfer (EGT) from the intracellular cyanobacterium to the nucleus is widely recognized as a critical factor in the evolution of photosynthetic eukaryotes. The contribution of horizontal gene transfers (HGTs) from other bacteria to plastid establishment remains more controversial. A novel perspective on this issue is provided by the amoeba Paulinella chromatophora, which contains photosynthetic organelles (Chromatophores) that are only 60–200 million years old. Chromatophore genome reduction entailed the loss of many biosynthetic pathways including those for numerous amino acids and cofactors. How the host cell compensates for these losses remains unknown, because the presence of bacteria in all available P. chromatophora cultures excluded elucidation of the full metabolic capacity and occurrence of HGT in this species. Here we generated a high-quality transcriptome and draft genome assembly from the first bacteria-free P. chromatophora culture to deduce rules that govern organelle integration into cellular metabolism. Our analyses revealed that nuclear and chromatophore gene inventories provide highly complementary functions. At least 229 nuclear genes were acquired via HGT from various bacteria, of which only 25% putatively arose through EGT from the chromatophore genome. Many HGT-derived bacterial genes encode proteins that fill gaps in critical chromatophore pathways/processes. Our results demonstrate a dominant role for HGT in compensating for organelle genome reduction and suggest that phagotrophy may be a major driver of HGT.
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Chromatophore Genome Sequence of Paulinella Sheds Light on Acquisition of Photosynthesis by Eukaryotes
Current biology : CB, 2008Co-Authors: Eva C M Nowack, Michael Melkonian, Gernot GlöcknerAbstract:Summary Background It is commonly accepted that a single primary endosymbiosis gave rise to the photosynthetic organelles of plants, the plastids. Recently, we presented evidence that photosynthetic inclusions, termed "Chromatophores," present in the filose thecamoeba Paulinella chromatophora originated from an independent, more recent primary endosymbiotic event. To clarify metabolic capabilities of the chromatophore and its state of integration into the host, we present here the complete genome sequence of the chromatophore. Results Our data reveal a fundamental reduction of the chromatophore genome. The single, circular chromosome of 1.02 Mb encodes 867 protein-coding genes and is, therewith, the smallest cyanobacterial genome reported to date. Compared to Synechococcus WH5701, a free-living relative of the chromatophore, only 26% of the genes were retained. Eleven putative pseudogenes were identified, indicating that reductive genome evolution is ongoing. Although the chromatophore genome contains a complete set of photosynthesis genes, it lacks not only genes thought to be dispensable for an intracellular lifestyle but also genes of essential pathways for amino acid and cofactor synthesis. Conclusions Our data characterize the chromatophore as a photosynthetic entity that is absolutely dependent on its host for growth and survival. Thus, the Chromatophores of P. chromatophora are the only known cyanobacterial descendants besides plastids with a significantly reduced genome that confer photosynthesis to their eukaryotic host. Their comparison with plastids and bacterial endosymbionts of invertebrates sheds light on early steps of the integration of a photosynthetic prokaryote into a eukaryotic cell.
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the ancestor of the paulinella chromatophore obtained a carboxysomal operon by horizontal gene transfer from a nitrococcus like γ proteobacterium
BMC Evolutionary Biology, 2007Co-Authors: Birger Marin, Eva C M Nowack, Gernot Glöckner, Michael MelkonianAbstract:Paulinella chromatophora is a freshwater filose amoeba with photosynthetic endosymbionts (Chromatophores) of cyanobacterial origin that are closely related to free-living Prochlorococcus and Synechococcus species (PS-clade). Members of the PS-clade of cyanobacteria contain a proteobacterial form 1A RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) that was acquired by horizontal gene transfer (HGT) of a carboxysomal operon. In rDNA-phylogenies, the Paulinella chromatophore diverged basal to the PS-clade, raising the question whether the HGT occurred before or after the split of the chromatophore ancestor. Phylogenetic analyses of the almost complete rDNA operon with an improved taxon sampling containing most known cyanobacterial lineages recovered the Paulinella chromatophore as sister to the complete PS-clade. The sequence of the complete carboxysomal operon of Paulinella was determined. Analysis of RubisCO large subunit (rbcL) sequences revealed that Paulinella shares the proteobacterial form 1A RubisCO with the PS-clade. The γ-proteobacterium Nitrococcus mobilis was identified as sister of the Paulinella chromatophore and the PS-clade in the RubisCO phylogeny. Gene content and order in the carboxysomal operon correlates well with the RubisCO phylogeny demonstrating that the complete carboxysomal operon was acquired by the common ancestor of the Paulinella chromatophore and the PS-clade through HGT. The carboxysomal operon shows a significantly elevated AT content in Paulinella, which in the rbcL gene is confined to third codon positions. Combined phylogenies using rbcL and the rDNA-operon resulted in a nearly fully resolved tree of the PS-clade. The HGT of the carboxysomal operon predated the divergence of the chromatophore ancestor from the PS-clade. Following HGT and divergence of the chromatophore ancestor, diversification of the PS-clade into at least three subclades occurred. The γ-proteobacterium Nitrococcus mobilis represents the closest known relative to the donor of the carboxysomal operon. The isolated position of the Paulinella chromatophore in molecular phylogenies as well as its elevated AT content suggests that the Paulinella chromatophore has already undergone typical steps in the reductive evolution of an endosymbiont.
Masakazu Iwasaka - One of the best experts on this subject based on the ideXlab platform.
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effects of static magnetic fields on light scattering in red chromatophore of goldfish scale
Journal of Applied Physics, 2010Co-Authors: Masakazu IwasakaAbstract:Light scattering in a guanine crystal plate of goldfish scales was observed with and without static magnetic field exposure. Under a microscopic image with dark-field-illumination, the structural color of the scale by guanine plates was observed, and isolated Chromatophores showed a twinkling which was the intermittent light scattering of the light from the side. The light scattering was quenched by static magnetic fields of more than 0.26 tesla (T). The quenching was reversibly occurred when the applied external magnetic fields were changed between ambient fields and 5 T. The quenched light scattering did not improve when the magnetic field was decreased from 5 to 0.3 T. It recovered to the original twinkling state about one minute after reaching an ambient geomagnetic field level. The mechanism of the quenched light scattering was speculated to be concerned with the possible magnetic orientation of guanine crystal plates, which were sustained by protein fibers in the red chromatophore. The diamagnetic c...
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effects of static magnetic fields on light scattering in red chromatophore of goldfish scale
Journal of Applied Physics, 2010Co-Authors: Masakazu IwasakaAbstract:Light scattering in a guanine crystal plate of goldfish scales was observed with and without static magnetic field exposure. Under a microscopic image with dark-field-illumination, the structural color of the scale by guanine plates was observed, and isolated Chromatophores showed a twinkling which was the intermittent light scattering of the light from the side. The light scattering was quenched by static magnetic fields of more than 0.26 tesla (T). The quenching was reversibly occurred when the applied external magnetic fields were changed between ambient fields and 5 T. The quenched light scattering did not improve when the magnetic field was decreased from 5 to 0.3 T. It recovered to the original twinkling state about one minute after reaching an ambient geomagnetic field level. The mechanism of the quenched light scattering was speculated to be concerned with the possible magnetic orientation of guanine crystal plates, which were sustained by protein fibers in the red chromatophore. The diamagnetic complex of guanine crystal plates and protein fibers are the candidates for the nanosized light scattering controller based on the magnetic orientation mechanism.
Leila F Deravi - One of the best experts on this subject based on the ideXlab platform.
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optical extinction of size controlled aerosols generated from squid chromatophore pigments
APL Materials, 2017Co-Authors: Sean R Dinneen, Margaret E Greenslade, Leila F DeraviAbstract:Nanophotonic granules populate the interior of cephalopod Chromatophores, contributing to their visible color by selectively absorbing and scattering light. Inspired by the performance of these granules, we fabricated nanostructured aerosols by nebulizing a pigment solution extracted from native squid Chromatophores. We determined their optical extinction using cavity ring-down spectroscopy and show how extinction cross section is dependent on both particle concentration and size. This work not only advances the fundamental knowledge of the optical properties of chromatophore pigments but also serves as a proof-of-concept method that can be adapted to develop coatings derived from these pigmentary aerosols.
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progress towards elucidating the structure function relationships of a natural nanoscale photonic device in cuttlefish Chromatophores
Proceedings of SPIE, 2015Co-Authors: Leila F Deravi, Andrew P Magyar, Sean P Sheehy, George R R Bell, Alan M. Kuzirian, Lydia M. Mäthger, Roger T. Hanlon, Kevin Kit ParkerAbstract:The adaptive coloration observed in cuttlefish Sepia officinalis skin is facilitated in part by properties of pigmented Chromatophores that have not been previously reported. We found that chromatophore coloration is enabled by a tethering system that distributes layered pigment granules, comprised of fluorescent nanostructures, to optimize color intensity as the Chromatophores are actuated. The design features gleaned from these studies provide intriguing insights into the development of artificial photonic systems useful for products ranging from conformable, high-definition color displays to optical fabrics capable of adapting their coloration within an ambient environment.
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the structure function relationships of a natural nanoscale photonic device in cuttlefish Chromatophores
Journal of the Royal Society Interface, 2014Co-Authors: Leila F Deravi, Andrew P Magyar, Sean P Sheehy, George R R Bell, Stephen L. Senft, Alan M. Kuzirian, Lydia M. Mäthger, Trevor J. Wardill, William S Lane, Roger T. HanlonAbstract:Cuttlefish, Sepia officinalis, possess neurally controlled, pigmented chromatophore organs that allow rapid changes in skin patterning and coloration in response to visual cues. This process of adaptive coloration is enabled by the 500% change in chromatophore surface area during actuation. We report two adaptations that help to explain how colour intensity is maintained in a fully expanded chromatophore when the pigment granules are distributed maximally: (i) pigment layers as thin as three granules that maintain optical effectiveness and (ii) the presence of high-refractive-index proteins—reflectin and crystallin—in granules. The latter discovery, combined with our finding that isolated chromatophore pigment granules fluoresce between 650 and 720 nm, refutes the prevailing hypothesis that cephalopod Chromatophores are exclusively pigmentary organs composed solely of ommochromes. Perturbations to granular architecture alter optical properties, illustrating a role for nanostructure in the agile, optical responses of Chromatophores. Our results suggest that cephalopod chromatophore pigment granules are more complex than homogeneous clusters of chromogenic pigments. They are luminescent protein nanostructures that facilitate the rapid and sophisticated changes exhibited in dermal pigmentation.
Klaus Schulten - One of the best experts on this subject based on the ideXlab platform.
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overall energy conversion efficiency of a photosynthetic vesicle
eLife, 2016Co-Authors: Melih Sener, Neil C Hunter, Abhishek Singharoy, Johan Strumpfer, Klaus SchultenAbstract:Photosynthesis, or the conversion of light energy into chemical energy, is a process that powers almost all life on Earth. Plants and certain bacteria share similar processes to perform photosynthesis, though the purple bacterium Rhodobacter sphaeroides uses a photosynthetic system that is much less complex than that in plants. Light harvesting inside the bacterium takes place in up to hundreds of compartments called Chromatophores. Each chromatophore in turn contains hundreds of cooperating proteins that together absorb the energy of sunlight and convert and store it in molecules of ATP, the universal energy currency of all cells. The chromatophore of primitive purple bacteria provides a model for more complex photosynthetic systems in plants. Though researchers had characterized its individual components over the years, less was known about the overall architecture of the chromatophore and how its many components work together to harvest light energy efficiently and robustly. This knowledge would provide insight into the evolutionary pressures that shaped the chromatophore and its ability to work efficiently at different light intensities. Sener et al. now present a highly detailed structural model of the chromatophore of purple bacteria based on the findings of earlier studies. The model features the position of every atom of the constituent proteins and is used to examine how energy is transferred and converted. Sener et al. describe the sequence of energy conversion steps and calculate the overall energy conversion efficiency, namely how much of the light energy arriving at the microorganism is stored as ATP. These calculations show that the chromatophore is optimized to produce chemical energy at low light levels typical of purple bacterial habitats, and dissipate excess energy to avoid being damaged under brighter light. The chromatophore’s architecture also displays robustness against perturbations of its components. In the future, the approach used by Sener et al. to describe light harvesting in this bacterial compartment can be applied to more complex systems, such as those in plants.
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integration of energy and electron transfer processes in the photosynthetic membrane of rhodobacter sphaeroides
Biochimica et Biophysica Acta, 2014Co-Authors: Michael L Cartron, John D Olsen, Melih Sener, Klaus Schulten, Pu Qian, Philip J Jackson, Amanda A Brindley, Mark J Dickman, Graham J Leggett, Neil C HunterAbstract:Photosynthesis converts absorbed solar energy to a protonmotive force, which drives ATP synthesis. The membrane network of chlorophyll–protein complexes responsible for light absorption, photochemistry and quinol (QH2) production has been mapped in the purple phototrophic bacterium Rhodobacter (Rba.) sphaeroides using atomic force microscopy (AFM), but the membrane location of the cytochrome bc1 (cytbc1) complexes that oxidise QH2 to quinone (Q) to generate a protonmotive force is unknown. We labelled cytbc1 complexes with gold nanobeads, each attached by a Histidine10 (His10)-tag to the C-terminus of cytc1. Electron microscopy (EM) of negatively stained chromatophore vesicles showed that the majority of the cytbc1 complexes occur as dimers in the membrane. The cytbc1 complexes appeared to be adjacent to reaction centre light-harvesting 1-PufX (RC–LH1–PufX) complexes, consistent with AFM topographs of a gold-labelled membrane. His-tagged cytbc1 complexes were retrieved from Chromatophores partially solubilised by detergent; RC–LH1–PufX complexes tended to co-purify with cytbc1 whereas LH2 complexes became detached, consistent with clusters of cytbc1 complexes close to RC–LH1–PufX arrays, but not with a fixed, stoichiometric cytbc1–RC–LH1–PufX supercomplex. This information was combined with a quantitative mass spectrometry (MS) analysis of the RC, cytbc1, ATP synthase, cytaa3 and cytcbb3 membrane protein complexes, to construct an atomic-level model of a chromatophore vesicle comprising 67 LH2 complexes, 11 LH1–RC–PufX dimers & 2 RC–LH1–PufX monomers, 4 cytbc1 dimers and 2 ATP synthases. Simulation of the interconnected energy, electron and proton transfer processes showed a half-maximal ATP turnover rate for a light intensity equivalent to only 1% of bright sunlight. Thus, the photosystem architecture of the chromatophore is optimised for growth at low light intensities.
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Intrinsic Curvature Properties of Photosynthetic Proteins in Chromatophores
Biophysical journal, 2008Co-Authors: Danielle E. Chandler, Jen Hsin, Christopher B. Harrison, James C. Gumbart, Klaus SchultenAbstract:In purple bacteria, photosynthesis is carried out on large indentations of the bacterial plasma membrane termed Chromatophores. Acting as primitive organelles, Chromatophores are densely packed with the membrane proteins necessary for photosynthesis, including light harvesting complexes LH1 and LH2, reaction center (RC), and cytochrome bc1. The shape of Chromatophores is primarily dependent on species, and is typically spherical or flat. How these shapes arise from the protein-protein and protein-membrane interactions is still unknown. Now, using molecular dynamics simulations, we have observed the dynamic curvature of membranes caused by proteins in the chromatophore. A membrane-embedded array of LH2s was found to relax to a curved state, both for LH2 from Rps. acidophila and a homology-modeled LH2 from Rb. sphaeroides. A modeled LH1-RC-PufX dimer was found to develop a bend at the dimerizing interface resulting in a curved shape as well. In contrast, the bc1 complex, which has not been imaged yet in native Chromatophores, did not induce a preferred membrane curvature in simulation. Based on these results, a model for how the different photosynthetic proteins influence chromatophore shape is presented.