Identification of an Unpredicted GAG-PUL in <i>Roseihalotalea indica</i> gen. nov. sp. nov. TK19036<sup>T</sup> and Characterization of Novel GAG-Lyases with Unique Substrate Specificities

Glycosaminoglycans (GAGs) and their degrading enzymes have extensive applications and biotechnology and medicine, and play a crucial role in the recycling of organic matter in oceans. In this study, a potential GAG utilization gene cluster was identified in the genome of a novel marine <i>Bacteroidetes</i>, <i>Roseihalotalea indica</i> gen. nov. sp. nov. TK19036^T, through sole carbon source cultivation and differential proteomic analysis. Multiple GAG-lyases within this locus were purified and characterized. RiPL8 comprises a functionally unknown N-terminal domain and a catalytic C-terminal domain, exhibiting specificity for degrading hyaluronic acid (HA). The activity of RiPL35 is sensitive to Ca²⁺ ion concentration with an optimum at 10 mM. RiPL38 is the first reported member of the PL38 family capable of degrading HA and chondroitin sulfate (CS). In summary, our study reveals <i>Roseihalotalea indica</i> gen. nov. sp. nov. TK19036^T harbors an unpredicted GAG degradation gene cluster, and the encoded GAG-lyases exhibit distinct substrate specificities compared to the host organism.