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Cell Oct 2021Being able to precisely turn on or off particular neurons in the brain at will was a major challenge for the neuroscience field, and few could have anticipated that the...
Being able to precisely turn on or off particular neurons in the brain at will was a major challenge for the neuroscience field, and few could have anticipated that the solution would come from algae. The 2021 Albert Lasker Basic Medical Research Award recognizes the contributions of Peter Hegemann, Dieter Oesterhelt, and Karl Deisseroth for their discovery of light-sensitive microbial proteins that can activate or silence brain cells. Cell editor Nicole Neuman had a conversation with Peter Hegemann about his role in bridging the two fields of microbial phototaxis and neuroscience and his perspective on the nature and future of interdisciplinary science. Excerpts from this conversation are presented below, and the full conversation is available with the article online.
Topics: Awards and Prizes; Bacterial Proteins; Bacteriorhodopsins; Channelrhodopsins; Humans; Light; Optogenetics
PubMed: 34562361
DOI: 10.1016/j.cell.2021.08.009 -
Animal Cognition Nov 2023Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there... (Review)
Review
Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there are many extraocular strategies for light sensing. Here, we review how these simpler forms of detecting light can mediate rapid behavioural responses in animals. Examples of these behaviours include photophobic (light avoidance) or scotophobic (shadow) responses, photokinesis, phototaxis and wavelength discrimination. We review the cells and response mechanisms in these forms of elementary light detection, focusing on aquatic invertebrates with some protist and terrestrial examples to illustrate the general principles. Light cues can be used very efficiently by these simple photosensitive systems to effectively guide animal behaviours without investment in complex and energetically expensive visual structures.
Topics: Animals; Photoreceptor Cells; Eye; Light
PubMed: 37650997
DOI: 10.1007/s10071-023-01818-6 -
Archives of Biochemistry and Biophysics Jan 2021The lipid composition impacts directly on the structure and function of the cytoplasmic as well as organelle membranes. Depending on the type of membrane, specific... (Review)
Review
The lipid composition impacts directly on the structure and function of the cytoplasmic as well as organelle membranes. Depending on the type of membrane, specific lipids are required to accommodate, intercalate, or pack membrane proteins to the proper functioning of the cells/organelles. Rather than being only a physical barrier that separates the inner from the outer spaces, membranes are responsible for many biochemical events such as cell-to-cell communication, protein-lipid interaction, intracellular signaling, and energy storage. Photochemical reactions occur naturally in many biological membranes and are responsible for diverse processes such as photosynthesis and vision/phototaxis. However, excessive exposure to light in the presence of absorbing molecules produces excited states and other oxidant species that may cause cell aging/death, mutations and innumerable diseases including cancer. At the same time, targeting key compartments of diseased cells with light can be a promising strategy to treat many diseases in a clinical procedure called Photodynamic Therapy. Here we analyze the relationships between membrane alterations induced by photo-oxidation and the biochemical responses in mammalian cells. We specifically address the impact of photosensitization reactions in membranes of different organelles such as mitochondria, lysosome, endoplasmic reticulum, and plasma membrane, and the subsequent responses of eukaryotic cells.
Topics: Animals; Cell Membrane; Humans; Light; Oxidation-Reduction
PubMed: 33159891
DOI: 10.1016/j.abb.2020.108665 -
Microorganisms Mar 2022In this review, the general background is provided on cyanobacteria, including morphology, cell membrane structure, and their photosynthesis pathway. The presence of... (Review)
Review
In this review, the general background is provided on cyanobacteria, including morphology, cell membrane structure, and their photosynthesis pathway. The presence of cyanobacteria in nature, and their industrial applications are discussed, and their production of secondary metabolites are explained. Biofilm formation, as a common feature of microorganisms, is detailed and the role of cell diffusion in bacterial colonization is described. Then, the discussion is narrowed down to cyanobacterium , as a lab model microorganism. In this relation, the morphology of is discussed and its different elements are detailed. Type IV pili, the complex multi-protein apparatus for motility and cell-cell adhesion in is described and the underlying function of its different elements is detailed. The phototaxis behavior of the cells, in response to homogenous or directional illumination, is reported and its relation to the run and tumble statistics of the cells is emphasized. In suspensions, there may exist a reciprocal interaction between the cell and the carrying fluid. The effects of shear flow on the growth, doubling per day, biomass production, pigments, and lipid production of are reported. Reciprocally, the effects of presence and its motility on the rheological properties of cell suspensions are addressed. This review only takes up the general grounds of cyanobacteria and does not get into the detailed biological aspects per se. Thus, it is substantially more comprehensive in that sense than other reviews that have been published in the last two decades. It is also written not only for the researchers in the field, but for those in physics and engineering, who may find it interesting, useful, and related to their own research.
PubMed: 35456747
DOI: 10.3390/microorganisms10040696 -
Journal of Visualized Experiments : JoVE May 2022For the survival of the motile phototrophic microorganisms, being under proper light conditions is crucial. Consequently, they show photo-induced behaviors (or...
For the survival of the motile phototrophic microorganisms, being under proper light conditions is crucial. Consequently, they show photo-induced behaviors (or photobehavior) and alter their direction of movement in response to light. Typical photobehaviors include photoshock (or photophobic) response and phototaxis. Photoshock is a response to a sudden change in light intensity (e.g., flash illumination), wherein organisms transiently stop moving or move backward. During phototaxis, organisms move toward the light source or in the opposite direction (called positive or negative phototaxis, respectively). The unicellular green alga Chlamydomonas reinhardtii is an excellent organism to study photobehavior because it rapidly changes its swimming pattern by modulating the beating of cilia (a.k.a., flagella) after photoreception. Here, various simple methods are shown to observe photobehaviors in C. reinhardtii. Research on C. reinhardtii's photobehaviors has led to the discovery of common regulatory mechanisms between eukaryotic cilia and channelrhodopsins, which may contribute to a better understanding of ciliopathies and the development of new optogenetics methods.
Topics: Channelrhodopsins; Chlamydomonas reinhardtii; Flagella; Light; Phototaxis
PubMed: 35604154
DOI: 10.3791/63961 -
RSC Advances Feb 2023Rhodopsins, a family of photoreceptive membrane proteins, contain retinal as a chromophore and were firstly identified as reddish pigments from frog retina in 1876.... (Review)
Review
Rhodopsins, a family of photoreceptive membrane proteins, contain retinal as a chromophore and were firstly identified as reddish pigments from frog retina in 1876. Since then, rhodopsin-like proteins have been identified mainly from animal eyes. In 1971, a rhodopsin-like pigment was discovered from the archaeon and named bacteriorhodopsin. While it was believed that rhodopsin- and bacteriorhodopsin-like proteins were expressed only in animal eyes and archaea, respectively, before the 1990s, a variety of rhodopsin-like proteins (called animal rhodopsins or opsins) and bacteriorhodopsin-like proteins (called microbial rhodopsins) have been progressively identified from various tissues of animals and microorganisms, respectively. Here, we comprehensively introduce the research conducted on animal and microbial rhodopsins. Recent analysis has revealed that the two rhodopsin families have common molecular properties, such as the protein structure (, 7-transmembrane structure), retinal structure (, binding ability to - and -retinal), color sensitivity (, UV- and visible-light sensitivities), and photoreaction (, triggering structural changes by light and heat), more than what was expected at the early stages of rhodopsin research. Contrastingly, their molecular functions are distinctively different (, G protein-coupled receptors and photoisomerases for animal rhodopsins and ion transporters and phototaxis sensors for microbial rhodopsins). Therefore, based on their similarities and dissimilarities, we propose that animal and microbial rhodopsins have convergently evolved from their distinctive origins as multi-colored retinal-binding membrane proteins whose activities are regulated by light and heat but independently evolved for different molecular and physiological functions in the cognate organism.
PubMed: 36793294
DOI: 10.1039/d2ra07073a -
Biochemistry. Biokhimiia Oct 2023Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that,... (Review)
Review
Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that, channelrhodopsins are widely used in neuroscience and cardiology as instruments for optogenetic manipulation of the activity of excitable cells. Photocurrents generated by channelrhodopsins were first discovered in the cells of green algae in the 1970s. In this review we describe this discovery and discuss the current state of research in the field.
Topics: Channelrhodopsins; Optogenetics; Phototaxis; Light; Ion Transport
PubMed: 38105024
DOI: 10.1134/S0006297923100115 -
Annual Review of Microbiology Jun 2024Widespread phytochrome photoreceptors use photoisomerization of linear tetrapyrrole (bilin) chromophores to measure the ratio of red to far-red light. Cyanobacteria also... (Review)
Review
Widespread phytochrome photoreceptors use photoisomerization of linear tetrapyrrole (bilin) chromophores to measure the ratio of red to far-red light. Cyanobacteria also contain distantly related cyanobacteriochrome (CBCR) proteins that share the bilin-binding GAF domain of phytochromes but sense other colors of light. CBCR photocycles are extremely diverse, ranging from the near-UV to the near-IR. Photoisomerization of the bilin triggers photoconversion of the CBCR input, thereby modulating the biochemical signaling state of output domains such as histidine kinase bidomains that can interface with cellular signal transduction pathways. CBCRs thus can regulate several aspects of cyanobacterial photobiology, including phototaxis, metabolism of cyclic nucleotide second messengers, and optimization of the cyanobacterial light-harvesting apparatus. This review examines spectral tuning, photoconversion, and photobiology of CBCRs and recent developments in understanding their evolution and in applying them in synthetic biology.
PubMed: 38848579
DOI: 10.1146/annurev-micro-041522-094613 -
Current Opinion in Structural Biology Aug 2019Enzymerhodopsins are a recently discovered class of natural rhodopsin-based photoreceptors with light-regulated enzyme activity. Currently, three different types of... (Review)
Review
Enzymerhodopsins are a recently discovered class of natural rhodopsin-based photoreceptors with light-regulated enzyme activity. Currently, three different types of these fusion proteins with an N-terminal type-1 rhodopsin and a C-terminal enzyme domain have been identified, but their physiological relevance is mostly unknown. Among these, histidine kinase rhodopsins (HKR) are photo-regulated two-component-like signaling systems that trigger a phosphorylation cascade, whereas rhodopsin phosphodiesterase (RhoPDE) or rhodopsin guanylyl cyclase (RhGC) show either light-activated hydrolysis or production of cyclic nucleotides. RhGC, the best characterized enzymerhodopsin, is involved in the phototaxis of fungal zoospores and allows for optically controlled production of cyclic nucleotides in different cell-types. These photoreceptors have great optogenetic potential and possess several advantages over the hitherto existing tools to manipulate cyclic-nucleotide dynamics in living cells.
Topics: Biocatalysis; Enzymes; Optogenetics; Rhodopsin
PubMed: 30954887
DOI: 10.1016/j.sbi.2019.02.003 -
Applied and Environmental Microbiology Jun 2023Filamentous cyanobacteria exhibit some of the greatest developmental complexity observed in the prokaryotic domain. This includes the ability to differentiate... (Review)
Review
Filamentous cyanobacteria exhibit some of the greatest developmental complexity observed in the prokaryotic domain. This includes the ability to differentiate nitrogen-fixing cells known as heterocysts, spore-like akinetes, and hormogonia, which are specialized motile filaments capable of gliding on solid surfaces. Hormogonia and motility play critical roles in several aspects of the biology of filamentous cyanobacteria, including dispersal, phototaxis, the formation of supracellular structures, and the establishment of nitrogen-fixing symbioses with plants. While heterocyst development has been investigated extensively at the molecular level, much less is known about akinete or hormogonium development and motility. This is due, in part, to the loss of developmental complexity during prolonged laboratory culture in commonly employed model filamentous cyanobacteria. In this review, recent progress in understanding the molecular level regulation of hormogonium development and motility in filamentous cyanobacteria is discussed, with a focus on experiments performed using the genetically tractable model filamentous cyanobacterium Nostoc punctiforme, which retains the developmental complexity of field isolates.
Topics: Gene Expression Regulation, Bacterial; Nostoc; Fimbriae, Bacterial; Symbiosis; Nitrogen; Bacterial Proteins
PubMed: 37199640
DOI: 10.1128/aem.00392-23