Comprehensive genomic and transcriptomic analysis of inositol phosphate-metabolizing enzymes in Euglena gracilis.

Main conclusion: Euglena gracilis possesses a dynamic inositol metabolic network, with enzyme expression varying under different growth conditions and stressors, enabling future synthetic engineering. Inositol and its phosphate derivatives play pivotal roles in energy metabolism and cellular signaling. Although inositol was detected in Euglena gracilis (E. gracilis) decades ago, the enzymatic machinery governing its metabolic conversion remains poorly characterized. In this study, we conducted a comprehensive bioinformatic analysis of inositol phosphate-metabolizing enzymes and identified 25 enzyme entries (encompassing 35 genes) in this protist. KEGG pathway mapping revealed an active inositol metabolic network in E. gracilis. Genomic structure analysis demonstrated that most of these genes are present in multiple copies across the genome. By constructing a miniaturized genomic representation of these enzymes, we investigated their transcriptional profiles under various conditions, including photo-, hetero-, and mixotrophic growth, aerobic and anaerobic environments, light and dark exposure, and treatment with ethanol, glucose, or other chemical stressors. Our findings indicate that inositol phosphate-metabolizing enzymes exhibit differential expression and dynamic regulation depending on physiological growth conditions and external stimuli. This study establishes a foundation for future catalytic characterization and synthetic engineering of inositol-related enzymes in E. gracilis.