Did you mean: chlamydomonas
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Cell Dec 2022The TOC and TIC complexes are essential translocons that facilitate the import of the nuclear genome-encoded preproteins across the two envelope membranes of...
The TOC and TIC complexes are essential translocons that facilitate the import of the nuclear genome-encoded preproteins across the two envelope membranes of chloroplast, but their exact molecular identities and assembly remain unclear. Here, we report a cryoelectron microscopy structure of TOC-TIC supercomplex from Chlamydomonas, containing a total of 14 identified components. The preprotein-conducting pore of TOC is a hybrid β-barrel co-assembled by Toc120 and Toc75, while the potential translocation path of TIC is formed by transmembrane helices from Tic20 and YlmG, rather than a classic model of Tic110. A rigid intermembrane space (IMS) scaffold bridges two chloroplast membranes, and a large hydrophilic cleft on the IMS scaffold connects TOC and TIC, forming a pathway for preprotein translocation. Our study provides structural insights into the TOC-TIC supercomplex composition, assembly, and preprotein translocation mechanism, and lays a foundation to interpret the evolutionary conservation and diversity of this fundamental translocon machinery.
Topics: Chloroplasts; Cryoelectron Microscopy; Intracellular Membranes; Protein Transport; Chlamydomonas; Multiprotein Complexes; Algal Proteins
PubMed: 36413996
DOI: 10.1016/j.cell.2022.10.030 -
Protoplasma Jul 2018
Topics: Cell Division; Cells; Chlamydomonas; Microscopy; Mutation
PubMed: 29862425
DOI: 10.1007/s00709-018-1273-6 -
The Plant Journal : For Cell and... May 2015Heat waves occurring at increased frequency as a consequence of global warming jeopardize crop yield safety. One way to encounter this problem is to genetically engineer... (Review)
Review
Heat waves occurring at increased frequency as a consequence of global warming jeopardize crop yield safety. One way to encounter this problem is to genetically engineer crop plants toward increased thermotolerance. To identify entry points for genetic engineering, a thorough understanding of how plant cells perceive heat stress and respond to it is required. Using the unicellular green alga Chlamydomonas reinhardtii as a model system to study the fundamental mechanisms of the plant heat stress response has several advantages. Most prominent among them is the suitability of Chlamydomonas for studying stress responses system-wide and in a time-resolved manner under controlled conditions. Here we review current knowledge on how heat is sensed and signaled to trigger temporally and functionally grouped sub-responses termed response elements to prevent damage and to maintain cellular homeostasis in plant cells.
Topics: Calcium; Cell Cycle Checkpoints; Cell Membrane; Chlamydomonas; Chlamydomonas reinhardtii; Heat-Shock Response; Plant Cells; Plant Proteins; Protein Kinases; Signal Transduction
PubMed: 25754362
DOI: 10.1111/tpj.12816 -
The Plant Journal : For Cell and... May 2015The position of Chlamydomonas within the eukaryotic phylogeny makes it a unique model in at least two important ways: as a representative of the critically important,... (Review)
Review
The position of Chlamydomonas within the eukaryotic phylogeny makes it a unique model in at least two important ways: as a representative of the critically important, early-diverging lineage leading to plants; and as a microbe retaining important features of the last eukaryotic common ancestor (LECA) that has been lost in the highly studied yeast lineages. Its cell biology has been studied for many decades and it has well-developed experimental genetic tools, both classical (Mendelian) and molecular. Unlike land plants, it is a haploid with very few gene duplicates, making it ideal for loss-of-function genetic studies. The Chlamydomonas cell cycle has a striking temporal and functional separation between cell growth and rapid cell division, probably connected to the interplay between diurnal cycles that drive photosynthetic cell growth and the cell division cycle; it also exhibits a highly choreographed interaction between the cell cycle and its centriole-basal body-flagellar cycle. Here, we review the current status of studies of the Chlamydomonas cell cycle. We begin with an overview of cell-cycle control in the well-studied yeast and animal systems, which has yielded a canonical, well-supported model. We discuss briefly what is known about similarities and differences in plant cell-cycle control, compared with this model. We next review the cytology and cell biology of the multiple-fission cell cycle of Chlamydomonas. Lastly, we review recent genetic approaches and insights into Chlamydomonas cell-cycle regulation that have been enabled by a new generation of genomics-based tools.
Topics: Animals; Cell Cycle; Chlamydomonas; Cytokinesis; Gene Expression Regulation; Mutation; Phylogeny; Plants; Viridiplantae
PubMed: 25690512
DOI: 10.1111/tpj.12795 -
Cell Reports Methods Aug 2023CRISPR-Cas genome engineering in the unicellular green algal model has until now been primarily applied to targeted gene disruption, whereas scarless knockin...
CRISPR-Cas genome engineering in the unicellular green algal model has until now been primarily applied to targeted gene disruption, whereas scarless knockin transgenesis has generally been considered difficult in practice. We have developed an efficient homology-directed method for knockin mutagenesis in Chlamydomonas by delivering CRISPR-Cas ribonucleoproteins and a linear double-stranded DNA (dsDNA) donor into cells by electroporation. Our method allows scarless integration of fusion tags and sequence modifications of proteins without the need for a preceding mutant line. We also present methods for high-throughput crossing of transformants and a custom quantitative PCR (qPCR)-based high-throughput screening of mutants as well as meiotic progeny. We demonstrate how to use this pipeline to facilitate the generation of mutant lines without residual selectable markers by co-targeted insertion. Finally, we describe how insertional cassettes can be erroneously mutated during insertion and suggest strategies to select for lines that are modified as designed.
Topics: Chlamydomonas reinhardtii; CRISPR-Cas Systems; Chlamydomonas; Culture; Electroporation
PubMed: 37671018
DOI: 10.1016/j.crmeth.2023.100562 -
The Plant Journal : For Cell and... Aug 2023Precise gene-editing using CRISPR/Cas9 technology remains a long-standing challenge, especially for genes with low expression and no selectable phenotypes in...
Precise gene-editing using CRISPR/Cas9 technology remains a long-standing challenge, especially for genes with low expression and no selectable phenotypes in Chlamydomonas reinhardtii, a classic model for photosynthesis and cilia research. Here, we developed a multi-type and precise genetic manipulation method in which a DNA break was generated by Cas9 nuclease and the repair was mediated using a homologous DNA template. The efficacy of this method was demonstrated for several types of gene editing, including inactivation of two low-expression genes (CrTET1 and CrKU80), the introduction of a FLAG-HA epitope tag into VIPP1, IFT46, CrTET1 and CrKU80 genes, and placing a YFP tag into VIPP1 and IFT46 for live-cell imaging. We also successfully performed a single amino acid substitution for the FLA3, FLA10 and FTSY genes, and documented the attainment of the anticipated phenotypes. Lastly, we demonstrated that precise fragment deletion from the 3'-UTR of MAA7 and VIPP1 resulted in a stable knock-down effect. Overall, our study has established efficient methods for multiple types of precise gene editing in Chlamydomonas, enabling substitution, insertion and deletion at the base resolution, thus improving the potential of this alga in both basic research and industrial applications.
Topics: CRISPR-Cas Systems; Chlamydomonas; Gene Editing; Chlamydomonas reinhardtii
PubMed: 37310200
DOI: 10.1111/tpj.16265 -
Eukaryotic Cell Apr 2008
Review
Topics: Algal Proteins; Animals; Chlamydomonas; Nitrates; Protozoan Proteins
PubMed: 18310352
DOI: 10.1128/EC.00431-07 -
Current Opinion in Plant Biology Jun 2017Ultraviolet-B radiation (UV-B) is an intrinsic part of the solar radiation that reaches the Earth's surface and affects the biosphere. Plants have evolved a specific... (Review)
Review
Ultraviolet-B radiation (UV-B) is an intrinsic part of the solar radiation that reaches the Earth's surface and affects the biosphere. Plants have evolved a specific UV-B signaling pathway mediated by the UVR8 photoreceptor that regulates growth, development, and acclimation. Major recent advances have contributed to our understanding of the UVR8 photocycle, UV-B-responsive protein-protein interactions, regulation of UVR8 subcellular localization, and UVR8-regulated physiological responses. Here, we review the latest progress in our understanding of UVR8 signaling and UV-B responses, which includes studies in the unicellular alga Chlamydomonas reinhardtii and the flowering plant Arabidopsis.
Topics: Arabidopsis; Chlamydomonas; Gene Expression Regulation, Plant; Photoreceptors, Plant; Signal Transduction; Ultraviolet Rays
PubMed: 28411583
DOI: 10.1016/j.pbi.2017.03.013 -
Nucleic Acids Research Nov 2023Riboregulators such as riboswitches and RNA thermometers provide simple, protein-independent tools to control gene expression at the post-transcriptional level. In...
Riboregulators such as riboswitches and RNA thermometers provide simple, protein-independent tools to control gene expression at the post-transcriptional level. In bacteria, RNA thermometers regulate protein synthesis in response to temperature shifts. Thermometers outside of the bacterial world are rare, and in organellar genomes, no RNA thermometers have been identified to date. Here we report the discovery of an RNA thermometer in a chloroplast gene of the unicellular green alga Chlamydomonas reinhardtii. The thermometer, residing in the 5' untranslated region of the psaA messenger RNA forms a hairpin-type secondary structure that masks the Shine-Dalgarno sequence at 25°C. At 40°C, melting of the secondary structure increases accessibility of the Shine-Dalgarno sequence to initiating ribosomes, thus enhancing protein synthesis. By targeted nucleotide substitutions and transfer of the thermometer into Escherichia coli, we show that the secondary structure is necessary and sufficient to confer the thermometer properties. We also demonstrate that the thermometer provides a valuable tool for inducible transgene expression from the Chlamydomonas plastid genome, in that a simple temperature shift of the algal culture can greatly increase recombinant protein yields.
Topics: RNA; Temperature; Thermometers; Chlamydomonas; Genome, Chloroplast; Protein Biosynthesis; Chlamydomonas reinhardtii; Riboswitch
PubMed: 37855670
DOI: 10.1093/nar/gkad816 -
Journal of Basic Microbiology Oct 2022Light plays a crucial role in photosynthesis, photoperiodism, and photomorphogenesis. Algae have a specialized visual system to perceive the light signal known as... (Review)
Review
Light plays a crucial role in photosynthesis, photoperiodism, and photomorphogenesis. Algae have a specialized visual system to perceive the light signal known as eyespot. A typical eyespot is an orange-colored, membranous structure packed with pigmented granules. In algae, the eyespot membrane bears a specialized type of photoreceptors, which shows similarity with animal rhodopsin photoreceptors. This light-sensing receptor is responsible for the photo-mobility response known as phototaxis. In this, light acts as a signal for onset and cascade of downstream signal transduction pathway leading to a conformational change in photoreceptor. This induces the continuous influx of calcium ions through the opening of calcium ion channels leading to membrane depolarization, and beating of flagella which is responsible for phototaxis. Mutational studies have assisted the discovery of eyespot genes, which are involved in eyespot development, assembly, size control, and functioning in Chlamydomonas. These genes belong to photoreceptors (cop1-12, acry, pcry, cry-dash1, cry-dash2, phot, uvr8), eyeless mutants (eye2, eye3), miniature-eyespot mutants (min1, min2), multiple eyespot mutants (mlt1, mlt2). This review discusses the structural biology of eyespots with special reference to Chlamydomonas, molecular insights, related genes, and proteins responsible for its proper functioning.
Topics: Animals; Calcium; Calcium Channels; Chlamydomonas; Chlamydomonas reinhardtii; Light; Rhodopsin
PubMed: 35778815
DOI: 10.1002/jobm.202200249