Inferred Subcellular Localization of Peroxisomal Matrix Proteins of Guillardia theta Suggests an Important Role of Peroxisomes in Cryptophytes

Abstract

Peroxisomes participate in several important metabolic processes in eukaryotic cells, such as the detoxification of reactive oxygen species (ROS) or the degradation of fatty acids by β-oxidation. Recently, the presence of peroxisomes in the cryptophyte Guillardia theta and other “chromalveolates” was revealed by identifying proteins for peroxisomal biogenesis. Here, we investigated the subcellular localization of candidate proteins of G. theta in the diatom Phaeodactylum tricornutum, either possessing a putative peroxisomal targeting signal type 1 (PTS1) sequence or factors lacking a peroxisomal targeting signal but known to be involved in β-oxidation. Our results indicate important contributions of the peroxisomes of G. theta to the carbohydrate, ether phospholipid, nucleotide, vitamin K, ROS, amino acid, and amine metabolisms. Moreover, our results suggest that in contrast to many other organisms, the peroxisomes of G. theta are not involved in the β-oxidation of fatty acids, which exclusively seems to occur in the cryptophyte's mitochondria.

Analysis of ginseng rusty root symptoms transcriptome and its pathogenesis directed by reactive oxygen species theory

“…Only 295 specific DEGs exist in the AG versus CG comparison, but most are upstream genes involved in stress response pathways. For instance, ACOX is the upstream gene of the peroxisome pathway, which is closely associated with oxidative stress in plants (Vasilev et al, 2022). For the rusty ginseng, DEGs in CG were also the marker genes of GRS, but it was only the result of GRS, not the cause.…”

Sharing the wealth: The versatility of proteins targeted to peroxisomes and other organelles

“…Mitochondrial enzymes probably became retargeted to peroxisomes over time, and some of these still remained dually localized ( Gabaldón, 2018 ). Indeed, recent work shows that the early diverged cryptophyte Guillardia theta contains peroxisomes, but enzymes for fatty acid oxidation seem to be only mitochondrial ( Vasilev et al, 2022 ). Independent of the actual evolutionary scenario, both the ER and mitochondria likely contributed to the proteome of modern peroxisomes and still sustain their biogenesis.…”

Molecular Mechanisms and Physiological Significance of Organelle Interactions and Cooperation - Volume II

“…Mitochondrial enzymes probably became retargeted to peroxisomes over time, and some of these still remained dually localized (Gabaldón, 2018). Indeed, recent work shows that the early diverged cryptophyte Guillardia theta contains peroxisomes, but enzymes for fatty acid oxidation seem to be only mitochondrial (Vasilev et al, 2022). Independent of the actual evolutionary scenario, both the ER and mitochondria likely contributed to the proteome of modern peroxisomes and still sustain their biogenesis.…”