Genome-wide Identification And Analysis Of Amino Acid Transporter Family In The Silkworm,Bombyx Mori

The Bombyx mori is an important model insect of the Lepidoptera and an important economic animal.Amino acid is the basic nutrient unit for protein synthesis and cell growth.It is also an important metabolic intermediate and promotes a variety of cell functions.Metazoa such as silkworm absorb and transport amino acids through amino acid transporters and detect the amount of amino acids inside and outside the cells.Amino acid transporter plays an important role in nutrient supply and balance,nervous system regulation,signal pathway regulation,and virus infection.Up to now,there has not been a comprehensive and systematic report on the identification and analysis of amino acid transporters in silkworm.Studies have shown that the susceptibility of the silkworm to Bombyx mori bidensovirus(Bm BDV)is determined by the putative amino acid transporter protein +NSD-2,which is specifically expressed in the midgut.The deletion of the nine transmembrane domains of this protein results the silkworm insensitive to viruses,but the mechanism of +NSD-2 regulating virus replication remains to be further elucidated.In this thesis,we will identify and analyze the amino acid transporters in the silkworm based on genome-wide;then identify the amino acid transporters expressed in the midgut of the silkworm at the transcriptome level,and compare the expression differences of these amino acid transporters after Bm BDV infection;finally,we use bioinformatics methods to predict the function of+NSD-2.The research content and main conclusions of this paper are as follows:1.First,we classified insect amino acid transporters according to the TCDB database.According to the TC classification system,the AEC amino acid transporter family of eukaryotes has no homologous proteins in insects,insect amino acid transporters can be divided into 8 families.Then,using the amino acid sequence of the clearly classified metazoa amino acid transporter in the TCDB database as the representative sequence,based on the whole genome data of the silkworm,17 members of the APC family,24 members of AAAP family,2 members of DAACS family,3members of POT family,16 members of NSS family,9 members of SSS family,93 members of MFS family and 31 members of MC family were identified.These genes encode proteins with a length of 123-1799 amino acid residues.The silkworm amino acid transporter gene of the APC superfamily was mapped to the silkworm chromosome.It was found that there are 10 genes on chromosome 1,9 genes on chromosome 13,and10 chromosomes have no amino acid transporter gene mapping.These genes may have gene duplication and gene expansion in the course of evolution.2.In order to study the amino acid transporters expressed in the midgut of the silkworm and the expression changes of these proteins after Bm BDV infection,we used two silkworm strains,Huaba 35 and Huaba BC7,at 0 h,6 h,and 48 h after Bm BDV infection as the samples.Based on the results of high-throughput sequencing of midgut RNA,118 silkworm amino acid transporter genes were identified to be expressed in the midgut,and 37 of them are differentially expressed genes related to Bm BDV infection.GO analysis and KEGG analysis of the differential genes suggest that these differential genes are mainly involved in N-glycan biosynthesis,material exchange metabolism,protein synthesis and processing and some other process.3.In order to analyze the molecular function of +NSD-2,this research first used bioinformatics to study the basic biological properties of +NSD-2.We found that the putative receptor of Bm BDV,+NSD-2,contains 12 transmembrane domains,and its functional domains is SNF(pfam: PF00209),which belongs to the amino acid transporter NSS family.The protein is mainly located on the cell membrane,with 8glycosylation sites and 44 phosphorylation sites.Although the protein is highly conserved with other insect homologous proteins,it is not conserved between most of the predicted glycosylation sites.Furthermore,the research combined +NSD-2 with known amino acid sensors to construct a phylogenetic tree and found that the protein can be clustered in the same branch with the known amino acid sensor and has 18.18%-45.45% similarity with the known amino acid sensors.The interaction protein prediction shows that +NSD-2 has an indirect interaction with Rheb,and the molecular function prediction shows that +NSD-2 has an interaction with Rag GTPase.We speculate that +NSD-2 may function as an amino acid sensor,participate in amino acid signal transduction,regulate m TORC1 signaling pathway and autophagy,and then regulate virus replication.This research has laid a foundation for further research on the function of amino acid transporters in Bombyx mori,and provided clues for the elucidation of the resistance mechanism and replication mechanism of the Bombyx mori Bidensovirus.