Sialic acid binding lectins (SABL) from molluscs, a review and insilico study of SABL from Solen grandis and Limax flavus
Members of Phyllum Mollusca with aquatic existence are exposed to pathogens. Their innate immune system comprises of both cellular and humoral immune responses. Many members are known to synthesise lectins that confer innate immunity. Sialic acid binding lectins (SABLs) show high specificity towards N-acetylneuraminic acid (NeuNAc), N-Glycolylneuraminic acid (Neu5Gc) and Nacetyl-9-0-acetylneuraminic acid (Neu5, 9Ac2). No study on their crystal structure on SABLs from Mollusca exists and therefore we have analysed the only complete sequences from the genebank and performed insilico analysis to understand the 3D structures. We discuss in this article structural peculiarities in SABL from Solen grandis and Limax flavus through insilico approaches. While all the SABLs with complete sequences had a conserved C1q complement domain, which may play role in bacterial recognition, Solen grandis SABL has an additional domain with similarity to Prefoldin with a probable molecular chaperon like activity and Limaxflavus has domains bearing homology to fibrinogen-related domains (Fred) superfamily with probable role in blood clotting and are unique amongst molluscan SABLs. Their characterisation remains the future scope of the study.