Construction of metabolic protein-protein interaction network of Eriocheir sinensis and molecular function, subcellular location and pathway analysis

Various diseases caused by metabolic abnormalities have caused great losses to the breeding industry of Eriocheir sinensis. Therefore, the study of the metabolic system of E. sinensis is very important for its healthy growth and development. However, there is still a lack of systematic analysis and research on the metabolic process of E. sinensis. , and this study aims to construct a systematic tool for the study on metabolic process of E. sinensis. Firstly, the proteins with unknown molecular functions were annotated based on the protein-protein interaction network (PIN) by annotating adjacent nodes. Secondly, based on the global network, the metabolic PIN of E. sinensis was constructed by extracting metabolism related proteins and their interaction relationships from the global network according to the GO annotation. The GO terms were organized in a hierarchical structure, among which, the highest level of metabolic system is annotated as GO: 0008152 (metabolic process). All the proteins that can be back traced to GO: 0008152 through the hierarchical structure were considered as metabolism related proteins. Then, the metabolism related proteins and their interaction relationships were extracted from the global network, which formed the metabolic PIN. Subsequently, the proteins in the network were annotated according to their molecular function and cellular component. Furthermore, the pathway distribution of the proteins in the metabolic PIN was analyzed according to the KEGG annotation of unigenes. The molecular functions of 932 proteins were determined, accounting for 97% of all unknown functional proteins in the network. The extracted metabolic PIN contains 2 045 proteins and 15 927 interactions. According to the molecular function and cellular component annotations, the functions and subcellular locations of the proteins in the network were further analyzed. 94.2% (1 926/2 045) of the proteins in the network had subcellular location information, and most of them were distributed in membranous organelles. 96.1% of the proteins (1 966/2 045) have molecular function information, and most of them have catalytic and binding activities. Analysis on the distribution of proteins in 40 subsystems showed that more proteins were involved in translation and amino acid metabolism, and some of them were involved in immune and transport processes. In this study, the metabolic PIN of E. sinensis was constructed for the first time, and the molecular function, subcellular location and pathway of the proteins were analyzed, which provided data basis for further study of metabolic activities and metabolism related proteins in E. sinensis. The results of this study can provide important data for the study of the function and location of metabolic proteins in E. sinensis.