Identification and characterization of ι-carrageenase from macroalgae-associated bacterium Microbulbifer sp. YNDZ01

BACKGROUND: In the present study, the iota-carrageenase gene, Car1293, was obtained from the genome of Microbulbifer sp. YNDZ01, which was isolated from the surface of macroalgae. To date, there are few studies on iota-carrageenase and the anti-inflammatory activity of iota-carrageenan oligosaccharides (CGOS). To enhance our perspective on iota-carrageenase and iota-carrageen oligosaccharides, the sequence, protein structure, enzymatic properties, enzymatic digestion products and anti-inflammatory activity of the gene were investigated. RESULTS: The gene length of Car1293 is 2,589 bp, encoding an enzyme with 862 amino acids, which shares 34% similarity with any previously reported iota-carrageenase. The spatial structure of Car1293 consists of many alpha-helices with a beta-fold binding module located at its terminus, and eight binding sites were found in the binding module as a result of docking with CGOS-DP4 ligand. The optimum temperature and pH for the activity of recombinant Car1293 toward. iota-carrageenan were 50 degrees C and 6.0, respectively. The hydrolysates of Car1293 are mainly degree of polymerization (DP)8, with minor products showing DP2, DP4, and DP6. The enzymatic hydrolysates CGOS-DP8 showed prominent anti-inflammatory activity, which was greater than that of the positive control L-monomethylarginine in lipopolysaccharide-induced RAW264.7 macrophages. It inhibited nitric oxide production, as well as significantly inhibited tumor necrosis factor-alpha and interleukin-6 secretion. CONCLUSION: The iota-carrageenase sequence encoded by Car1293 is novel and can hydrolyze carrageenan into CGOS-DP8 that has a significant anti-inflammatory effect. The present study fills a gap in the research on the biological activity of oligosaccharides in iota-carrageenan and provides promising data for the development of natural anti-inflammatory agent. (c) 2023 Society of Chemical Industry.

Automated summary

In this study, the iota-carrageenase gene Car1293 was obtained from Microbulbifer sp. YNDZ01, and its sequence, protein structure, enzymatic properties, enzymatic digestion products, and anti-inflammatory activity were investigated. The results showed that Car1293 encodes a novel enzyme that can hydrolyze carrageenan into CGOS-DP8 with significant anti-inflammatory activity. This study fills a gap in the research on the biological activity of oligosaccharides in iota-carrageenan and provides promising data for the development of natural anti-inflammatory agents.