Center for Integrative Genetics, Department of Animal and Aquacultural Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway.
Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway.
FEBS Open Bio. 2024 Jan;14(1):23-36. doi: 10.1002/2211-5463.13694. Epub 2023 Dec 4.
Atlantic salmon (Salmo salar) possesses a genome containing 10 genes encoding chitinases, yet their functional roles remain poorly understood. In other fish species, chitinases have been primarily linked to digestion, but also to other functions, as chitinase-encoding genes are transcribed in a variety of non-digestive organs. In this study, we investigated the properties of two chitinases belonging to the family 18 glycoside hydrolase group, namely Chia.3 and Chia.4, both isolated from the stomach mucosa. Chia.3 and Chia.4, exhibiting 95% sequence identity, proved inseparable using conventional chromatographic methods, necessitating their purification as a chitinase pair. Biochemical analysis revealed sustained chitinolytic activity against β-chitin for up to 24 h, spanning a pH range of 2 to 6. Moreover, subsequent in vitro investigations established that this chitinase pair efficiently degrades diverse chitin-containing substrates into chitobiose, highlighting the potential of Atlantic salmon to utilize novel chitin-containing feed sources. Analysis of the gastric matrix proteome demonstrates that the chitinases are secreted and rank among the most abundant proteins in the gastric matrix. This finding correlates well with the previously observed high transcription of the corresponding chitinase genes in Atlantic salmon stomach tissue. By shedding light on the secreted chitinases in the Atlantic salmon's stomach mucosa and elucidating their functional characteristics, this study enhances our understanding of chitinase biology in this species. Moreover, the observed capacity to effectively degrade chitin-containing materials implies the potential utilization of alternative feed sources rich in chitin, offering promising prospects for sustainable aquaculture practices.
大西洋鲑（Salmo salar）拥有一个包含 10 个编码几丁质酶基因的基因组，但其功能作用仍知之甚少。在其他鱼类中，几丁质酶主要与消化有关，但也与其他功能有关，因为编码几丁质酶的基因在各种非消化器官中转录。在这项研究中，我们研究了属于 18 糖苷水解酶家族的两种几丁质酶 Chia.3 和 Chia.4 的特性，这两种几丁质酶均从胃黏膜中分离出来。Chia.3 和 Chia.4 具有 95%的序列同一性，用常规的色谱方法无法分离，因此需要作为一对几丁质酶进行纯化。生化分析表明，它们对β-几丁质的几丁质酶活性可持续长达 24 小时，pH 范围为 2 到 6。此外，随后的体外研究表明，这种几丁质酶对各种含几丁质的底物具有高效的降解能力，将其降解为几丁二糖，这突出了大西洋鲑利用新型含几丁质饲料来源的潜力。对胃基质蛋白质组的分析表明，几丁质酶是分泌的，并且在胃基质中属于最丰富的蛋白质之一。这一发现与之前在大西洋鲑胃组织中观察到的相应几丁质酶基因的高转录水平很好地相关。通过阐明大西洋鲑胃黏膜中分泌的几丁质酶及其功能特性，本研究增进了我们对该物种几丁质酶生物学的理解。此外，观察到有效降解含几丁质物质的能力意味着可能利用富含几丁质的替代饲料来源，为可持续水产养殖实践提供了有前景的机会。
