Uncharacterized protein with amino acid deletions from Bombyx mori illustrates divergence from Bombyx mandarina hemocytin and showed modulated gene expression after infection by Nosema bombycis

Abstract

AbstractGenome wide gene expression analysis, transcription analysis and mass spectrometry have revealed several uncharacterized genes and proteins from commercial silkwormBombyx mori. Infection ofB. morilarvae with the microsporidianNosema bombycisinduced appearance of exclusive proteins in hemocytes ofB. morishowing host response. Mass spectrometry of the exclusive proteins revealed abundance of an uncharacterized protein H9JAZ8 that displayed conserved domains of Von Willebrand Factor type D domain (VWF), C8 domain, trypsin inhibitor-like cysteine rich domain and conserved epidermal growth factor like. Protein model of H9JAZ8 confirmed presence of VWF domains, cysteine rich domains and disulphide bonds. Expression ofH9JAZ8gene showed upregulation on day 2 after the infection followed by significant down regulated expression till day 10 exhibiting infection- associated modulation of the gene. BLASTP of H9JAZ8 showed 99% amino acid sequence similarity withB. moriBGIBMGA006693 demonstrating H9JAZ8 as a paralog ofB. morihemocytin. BLASTP of H9JAZ8 revealed 18 most similar hemocytin homologues from different insect species with 99% similarity forB. mandarinahemocytin. A Maximum Parsimony phylogeny tree showed three clusters where H9JAZ8 branched from the hemocytin ofB. mandarinawith 100% bootstrap value. Global BLAST analysis of H9JAZ8 with hemocytin ofB. mandarina(XP_028038271.1) showed deletion of two regions, a 27 amino acid stretch, RRIFFSFILIYCTFNCEAGYGIPASSD at 2–28th position and a 21 amino acid stretch, DVVVISPNHHNNSSYYSYSQG at 317-338th position. Togteher,B. moriH9JAZ8 is diverged fromB. mandarinahemocytin as part of speciation and immune evolution during domestication from the wild silkworm.