Effect of the Untranslated Regions on Characterization of Endochitinase CHIT37 in Saccharomyces Cerevisiae

In China, substantial amounts of shrimp and crab shells are generated as waste every year. Improper disposal of these shells will damage marine and coastal ecosystems. Due to the low added value of using shrimp and crab shells to produce chitin and chitosan products, a novel approach involves the further degradation of chitin and chitosan. Enhancing the efficiency of enzymatic hydrolysis proves pivotal in advancing the industrialization of enzyme solutions. Trichoderma harzianum stands out because of its enzyme production property. Our lab constructed an induced cDNA library of Trichoderma harzianum and obtained a novel chitinase gene, Chit37. To explore the impact of the 5ˊ- and 3ˊ-untranslated regions (UTRs) on the characterization of the endochitinase Chit37, we conducted heterologous expression experiments of the full-length gene (Chit37-I) and the coding region of the gene (Chit37-II) in Saccharomyces cerevisiae by integrating into plasmid shuttle vector pYES2. Both expressed products were secreted into the medium and exhibited measurable activity. Comparatively, Chit37-II demonstrated higher activity levels than Chit37-I throughout. The optimal reaction temperature, pH, and substrate concentration of Chit37-I and Chit37-II were 40 ℃, 5.0, and 5%, respectively. However, the optimal culture time differed, with 108 h for Chit37-I and 96 h for Chit37-II. Our findings suggest that the UTRs affect the Chit37 transcript level, while its regulation mechanism remains to be elucidated. The results can provide a valuable reference for the efficient utilization of shrimp and crab shells.