Preliminary analysis of PGRP-LC gene and structure characteristics in bumblebees

In: Sociobiology: an international journal on social insects, Volume 66, Issue 2, p. 348

Abstract

PGRP-LC is a significant pattern recognition receptor of the insect innate immune system that can recognize peptidoglycans and activate immune signaling pathways regulating the expression and release of antimicrobial peptides against infection. We for the first time analyzed the phylogenetic tree, purification and structure of bumblebee PGRP-LC. The results showed high conservation of bumblebee PGRP-LC among the 16 bumblebee species, and further phylogenetic analysis showed that the PGRP-LC phylogeny of different subgenera (Subterraneobombus, Megabombus, Melanobombus, Bombus) is consistent with that of the COI gene. Additionally, the phylogeny of PGRP-LCs among Bombus, Apis and the solitary bee Megachile rotundata coincides with the sociality evolution of bees. Moreover, bumblebee PGRP-LC (Bl-PGRP-LC) shares the Drosophila PGRP-LCx and PGRP-LCa topology, retaining conserved disulfide bonds and 80% binding residues involved in the interaction between TCT and PGRP-LCx. Therefore, Bl-PGRP-LC might share some similar binding characteristics with Drosophila PGRP-LCx. In addition, Bl-PGRP-LC has shorter β5 and β1 sheets, longer β2, β3, and β4 sheets and a shallow binding groove. To determine the characteristics of Bl-PGRP-LC, high-purity PGRP-LC inclusion bodies, soluble GST-tag Bl-PGRP-LC fusion protein and soluble pure Bl-PGRP-LC were obtained in vitro. The results will be helpful for further study of the function and structure of Bl-PGRP-LC.