Search Results (3)

Seasonal influenza epidemics caused by influenza A viruses (IAV) and influenza B viruses (IBV) pose a substantial public health burden. Despite the significant impact of IBV, its restricted host range and the absence of documented pandemics have resulted in limited research attention relative to IAV. Understanding the viral infection mechanisms of both IAV and IBV is crucial for controlling seasonal epidemics. Previously, we demonstrated that 3′-O-sulfated galactosylceramide sulfatide binds to IAV and enhances viral replication, a finding with potential therapeutic implications. However, the role sulfatide plays in other influenza virus infections, including those caused by IBV, remains unknown. Accordingly, in this paper, we investigate the function of sulfatide during IBV infection. We demonstrate that sulfatide binds to IBV hemagglutinin (HA), and that sulfatide overexpression significantly enhances IBV replication, whereas treatment with sulfatase or an anti-sulfatide antibody markedly suppressed IBV replication. Moreover, further tests involving the inhibition of sulfatide biosynthesis resulted in the suppression of viral replication with impaired nuclear export of viral ribonucleoproteins (vRNPs). These findings establish that sulfatide is a critical regulator of IBV replication, which parallels its role in IAV infection, and suggest that targeting sulfatide-virus interactions can lead to broad-spectrum therapeutic strategies against influenza virus. Full article

Sulfation is gaining increased interest due to the role of sulfate in the bioactivity of many polysaccharides of marine origin. Hence, sulfatases, enzymes that control the degree of sulfation, are being more extensively researched. In this work, a novel sulfatase (SulA1) encoded by the gene sulA1 was characterized. The sulA1-gene is located upstream of a chondroitin lyase encoding gene in the genome of the marine Arthrobacter strain (MAT3885). The sulfatase was produced in Escherichia coli. Based on the primary sequence, the enzyme is classified under sulfatase family 1 and the two catalytic residues typical of the sulfatase 1 family—Cys57 (post-translationally modified to formyl glycine for function) and His190—were conserved. The enzyme showed increased activity, but not improved stability, in the presence of Ca²⁺, and conserved residues for Ca²⁺ binding were identified (Asp17, Asp18, Asp277, and Asn278) in a structural model of the enzyme. The temperature and pH activity profiles (screened using p-nitrocatechol sulfate) were narrow, with an activity optimum at 40–50 °C and a pH optimum at pH 5.5. The T_m was significantly higher (67 °C) than the activity optimum. Desulfation activity was not detected on polymeric substrates, but was found on GalNAc4S, which is a sulfated monomer in the repeated disaccharide unit (GlcA–GalNAc4S) of, e.g., chondroitin sulfate A. The position of the sulA1 gene upstream of a chondroitin lyase gene and combined with the activity on GalNAc4S suggests that there is an involvement of the enzyme in the chondroitin-degrading cascade reaction, which specifically removes sulfate from monomeric GalNAc4S from chondroitin sulfate degradation products. Full article

Fucoidans belong to a structurally heterogeneous class of sulfated polysaccharides isolated from brown algae. They have a wide spectrum of biological activities. The complex structures of these polysaccharides hinder structure-activity relationships determination. Fucoidan sulfatases can make useful tools for the determination of the fine chemical structure of fucoidans. In this study, identification and preparation of two recombinant sulfatases able to catalyze the cleavage of sulfate groups from fragments of fucoidan molecules is described for the first time. Two genes of sulfatases swf1 and swf4 of the marine bacterium Wenyingzhuangia fucanilytica CZ1127^T were cloned and the proteins were produced in Escherichia coli cells. Sulfatases SWF1 and SWF4 are assigned to S1_17 and S1_25 subfamilies of formylglycine-dependent enzymes of S1 family (SulfAtlas). Some molecular and biochemical characteristics of recombinant fucoidan sulfatases have been studied. Detailed specificity and catalytic features of sulfatases were determined using various sulfated fucooligosaccharides. Structures of products produced by SWF1 and SWF4 were established by nuclear magnetic resonance (NMR) spectroscopy. Based on the obtained data, the enzymes are classified as fucoidan exo-2O-sulfatase (SWF1) and fucoidan exo-3O-sulfatase (SWF4). In addition, we demonstrated the sequential action of sulfatases on 2,3-di-O-sulfated fucooligosacchrides, which indicates an exolitic degradation pathway of fucoidan by a marine bacterium W. fucanilytica CZ1127^T. Full article