Proteomic analysis of scallop hepatopancreatic extract provides insights into marine polysaccharide digestion.

Qianqian Lyu,Weizhi Liu,Wenqian Jiao,Keke Zhang,Zhenmin Bao,Shi Wang

doi:10.1038/srep34866

Abstract

Marine polysaccharides are used in a variety of applications, and the enzymes that degrade these polysaccharides are of increasing interest. The main food source of herbivorous marine mollusks is seaweed, and several polysaccharide-degrading enzymes have been extracted from mollusk digestive glands (hepatopancreases). Here, we used a comprehensive proteomic approach to examine the hepatopancreatic proteins of the Zhikong scallop (Chlamys farreri). We identified 435 proteins, the majority of which were lysosomal enzymes and carbohydrate and protein metabolism enzymes. However, several new enzymes related to polysaccharide metabolism were also identified. Phylogenetic and structural analyses of these enzymes suggest that these polysaccharide-degrading enzymes may have a variety of potential substrate specificities. Taken together, our study characterizes several novel polysaccharide-degrading enzymes in the scallop hepatopancreas and provides an enhanced view of these enzymes and a greater understanding of marine polysaccharide digestion.

Highlights

New information relevant to the enzymatic adaptation of marine algal diets and a description of novel marine polysaccharide-degrading enzymes
Gene ontology (GO) term annotation and enrichment analysis of the scallop hepatopancreatic proteins demonstrated that the most enriched GO categories were metabolic and biological processes, including 109 proteins with hydrolytic activity (GO: 0016787) (P value: 5.72E-22) and 164 proteins associated with organic substance metabolic processes (GO: 0071704) (P value: 9.15E-15) (Table 1)
Both of these GO categories were dominated by glycoside hydrolases, sulfatases, proteinases and components of the proteasome, previously reported as lysosomal enzymes[17] (Table 1)

Summary

Introduction

New information relevant to the enzymatic adaptation of marine algal diets and a description of novel marine polysaccharide-degrading enzymes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated these hepatopancreatic proteins were significantly enriched in pathways involved in glycan degradation and the biosynthesis of amino acids as well as www.nature.com/scientificreports/ Eight α-L-fucosidase genes were identified in the scallop genome, and we detected seven of these in our mass spectroscopy analysis of hepatopancreatic proteins (Table 3).

Results

Conclusion