The ascorbate peroxidase-related protein: insights into its functioning in Chlamydomonas and Arabidopsis.

We review the newly classified ascorbate peroxidase-related (APX-R) proteins, which do not use ascorbate as electron donor to scavenge HO. We summarize recent discoveries on the function and the characterization of the APX-R protein of the green unicellular alga and the land plant . Additionally, we conduct analyses on the conserved MxxM motif, present in most of the APX-R protein in different organisms, which is proposed to bind copper.

Iron‑sulfur cluster synthesis in plastids by the SUF system: A mechanistic and structural perspective.

About 50 proteins expressed in plastids of photosynthetic eukaryotes ligate iron‑sulfur (Fe-S) clusters and ensure vital functions in photosynthesis, sulfur and nitrogen assimilation, but also in the synthesis of pigments, vitamins and hormones. The synthesis of these Fe-S clusters, which are co- or post-translationally incorporated into these proteins, relies on several proteins belonging to the so-called sulfur mobilization (SUF) machinery. An Fe-S cluster is first de novo synthesized on a scaffold protein complex before additional late-acting maturation factors act in the specific transfer, possible conversion and insertion of this cluster into target recipient proteins.

Heterotrophy Compared to Photoautotrophy for Growth Characteristics and Pigment Compositions in Batch Cultures of Four Green Microalgae.

Four strains of green microalgae (, , , and ) were compared to determine growth and pigment composition under photoautotrophic or heterotrophic conditions. Batch growth experiments were performed in multicultivators with online monitoring of optical density. For photoautotrophic growth, light-limited (CO-sufficient) growth was analyzed under different light intensities during the exponential and deceleration growth phases.

APX2 Is an Ascorbate Peroxidase-Related Protein that Regulates the Levels of Plastocyanin in Chlamydomonas.

The function of ascorbate peroxidase-related (APX-R) proteins, present in all green photosynthetic eukaryotes, remains unclear. This study focuses on APX-R from Chlamydomonas reinhardtii, namely, ascorbate peroxidase 2 (APX2). We showed that apx2 mutants exhibited a faster oxidation of the photosystem I primary electron donor, P700, upon sudden light increase and a slower re-reduction rate compared to the wild type, pointing to a limitation of plastocyanin.

Ascorbate Peroxidase 2 (APX2) of Chlamydomonas Binds Copper and Modulates the Copper Insertion into Plastocyanin.

Recent phylogenetic studies have unveiled a novel class of ascorbate peroxidases called "ascorbate peroxidase-related" (APX-R). These enzymes, found in green photosynthetic eukaryotes, lack the amino acids necessary for ascorbate binding. This study focuses on the sole APX-R from referred to as ascorbate peroxidase 2 (APX2).

Acclimation strategies of the green alga Chlorella vulgaris to different light regimes revealed by physiological and comparative proteomic analyses.

Acclimation to different light regimes is at the basis of survival for photosynthetic organisms, regardless of their evolutionary origin. Previous research efforts largely focused on acclimation events occurring at the level of the photosynthetic apparatus and often highlighted species-specific mechanisms. Here, we investigated the consequences of acclimation to different irradiances in Chlorella vulgaris, a green alga that is one of the most promising species for industrial application, focusing on both photosynthetic and mitochondrial activities.

Biolistic Transformation of Chlamydomonas reinhardtii and Saccharomyces cerevisiae Mitochondria.

Chlamydomonas reinhardtii and Saccharomyces cerevisiae are currently the two micro-organisms in which genetic transformation of mitochondria is routinely performed. The generation of a large variety of defined alterations as well as the insertion of ectopic genes in the mitochondrial genome (mtDNA) are possible, especially in yeast. Biolistic transformation of mitochondria is achieved through the bombardment of microprojectiles coated with DNA, which can be incorporated into mtDNA thanks to the highly efficient homologous recombination machinery present in S.

Molecular Advancements Establishing Chlamydomonas as a Host for Biotechnological Exploitation.

is emerging as a production platform for biotechnological purposes thanks to recent achievements, which we briefly summarize in this review. Firstly, robust nuclear transgene expression is now possible because several impressive improvements have been made in recent years. Strains allowing efficient and stable nuclear transgene expression are available and were recently made more amenable to rational biotechnological approaches by enabling genetic crosses and identifying their causative mutation.

Endothelial extracellular vesicles promote tumour growth by tumour-associated macrophage reprogramming.

Tumour-derived extracellular vesicles (EVs) participate in tumour progression by deregulating various physiological processes including angiogenesis and inflammation. Here we report that EVs released by endothelial cells in a mammary tumour environment participate in the recruitment of macrophages within the tumour, leading to an immunomodulatory phenotype permissive for tumour growth. Using RNA-Seq approaches, we identified several microRNAs (miRNAs) found in endothelial EVs sharing common targets involved in the regulation of the immune system.

A Fast-Growing Oleaginous Strain of Capable of Astaxanthin and Canthaxanthin Accumulation in Phototrophy and Heterotrophy.

Considering the importance of microalgae as a promising feedstock for the production of both low- and high-value products, such as lipids and pigments, it is desirable to isolate strains which simultaneously accumulate these two types of products and grow in various conditions in order to widen their biotechnological applicability. A novel freshwater strain from the genus was isolated in Belgium. Compared to other species, the isolate presented rapid growth in phototrophy, dividing 3.

Reactive oxygen species and organellar signaling.

The evolution of photosynthesis and its associated metabolic pathways has been crucial to the successful establishment of plants, but has also challenged plant cells in the form of production of reactive oxygen species (ROS). Intriguingly, multiple forms of ROS are generated in virtually every plant cell compartment through diverse pathways. As a result, a sophisticated network of ROS detoxification and signaling that is simultaneously tailored to individual organelles and safeguards the entire cell is necessary.

Occurrence, Evolution and Specificities of Iron-Sulfur Proteins and Maturation Factors in Chloroplasts from Algae.

Iron-containing proteins, including iron-sulfur (Fe-S) proteins, are essential for numerous electron transfer and metabolic reactions. They are present in most subcellular compartments. In plastids, in addition to sustaining the linear and cyclic photosynthetic electron transfer chains, Fe-S proteins participate in carbon, nitrogen, and sulfur assimilation, tetrapyrrole and isoprenoid metabolism, and lipoic acid and thiamine synthesis.

Mixotrophic growth of the extremophile Galdieria sulphuraria reveals the flexibility of its carbon assimilation metabolism.

Galdieria sulphuraria is a cosmopolitan microalga found in volcanic hot springs and calderas. It grows at low pH in photoautotrophic (use of light as a source of energy) or heterotrophic (respiration as a source of energy) conditions, using an unusually broad range of organic carbon sources. Previous data suggested that G.

Correction: Co-Evolution of Mitochondrial tRNA Import and Codon Usage Determines Translational Efficiency in the Green Alga Chlamydomonas.

[This corrects the article DOI: 10.1371/journal.pgen.

Assembly of Mitochondrial Complex I Requires the Low-Complexity Protein AMC1 in .

Complex I is the first enzyme involved in the mitochondrial electron transport chain. With >40 subunits of dual genetic origin, the biogenesis of complex I is highly intricate and poorly understood. We used as a model system to reveal factors involved in complex I biogenesis.

Metabolic, Physiological, and Transcriptomics Analysis of Batch Cultures of the Green Microalga Grown on Different Acetate Concentrations.

Acetate can be efficiently metabolized by the green microalga . The regular concentration is 17 mM, although higher concentrations are reported to increase starch and fatty acid content. To understand the responses to higher acetate concentrations, cells were cultivated in batch mode in the light at 17, 31, 44, and 57 mM acetate.

Characterization of the GPR1/FUN34/YaaH protein family in the green microalga suggests their role as intracellular membrane acetate channels.

The unicellular green microalga is a powerful photosynthetic model organism which is capable of heterotrophic growth on acetate as a sole carbon source. This capacity has enabled its use for investigations of perturbations in photosynthetic machinery as mutants can be recovered heterotrophically. Fixation of acetate into cellular carbon metabolism occurs first by its conversion into acetyl-CoA by a respective synthase and the generation of succinate by the glyoxylate cycle.

RNA-seq data and surprisal analysis of mutant and control strain of the green microalga during day/night cycles.

The data presented in this article are associated to the research article "Surprisal analysis of the transcriptomic response of the green microalga to the addition of acetate during day/night cycles" (Willamme et al., 2018) [1]. Here the RNA-seq data of the mutant, a null mutant of the isocitrate lyase gene, and its control are summarized and the FPKM values are listed.

Host-pathogen biotic interactions shaped vitamin K metabolism in Archaeplastida.

Menaquinone (vitamin K) shuttles electrons between membrane-bound respiratory complexes under microaerophilic conditions. In photosynthetic eukaryotes and cyanobacteria, phylloquinone (vitamin K) participates in photosystem I function. Here we elucidate the evolutionary history of vitamin K metabolism in algae and plants.

Insights into the respiratory chain and oxidative stress.

Reactive oxygen species (ROS) are highly reactive reduced oxygen molecules that result from aerobic metabolism. The common forms are the superoxide anion (O) and hydrogen peroxide (HO) and their derived forms, hydroxyl radical (HO∙) and hydroperoxyl radical (HOO∙). Their production sites in mitochondria are reviewed.

Surprisal analysis of genome-wide transcript profiling identifies differentially expressed genes and pathways associated with four growth conditions in the microalga Chlamydomonas.

The usual cultivation mode of the green microalga Chlamydomonas is liquid medium and light. However, the microalga can also be grown on agar plates and in darkness. Our aim is to analyze and compare gene expression of cells cultivated in these different conditions.