Molecular cloning and characterization of a short peptidoglycan recognition protein from silkworm Bombyx mori

Abstract

Peptidoglycan is the major bacterial component recognized by the insect immune system. Peptidoglycan recognition proteins (PGRPs) are a family of pattern-recognition receptors that recognize peptidoglycans and modulate innate immune responses. Some PGRPs retain N-acetylmuramoyl-L-alanine amidase (Enzyme Commission number: 3.5.1.28) activity to hydrolyse bacterial peptidoglycans. Others have lost the enzymatic activity and work only as immune receptors. They are all important modulators for innate immunity. Here, we report the cloning and functional analysis of PGRP-S4, a short-form PGRP from the domesticated silkworm, Bombyx mori. The PGRP-S4 gene encodes a protein of 199 amino acids with a signal peptide and a PGRP domain. PGRP-S4 was expressed in the fat body, haemocytes and midgut. Its expression level was significantly induced by bacterial challenges in the midgut. The recombinant PGRP-S4 bound bacteria and different peptidoglycans. In addition, it inhibited bacterial growth and hydrolysed an Escherichia coli peptidoglycan in the presence of Zn . Scanning electron microscopy showed that PGRP-S4 disrupted the bacterial cell surface. PGRP-S4 further increased prophenoloxidase activation caused by peptidoglycans. Taken together, our data suggest that B. mori PGRP-S4 has multiple functions in immunity.

Cloning and analysis of peptidoglycan recognition protein‐LC and immune deficiency from the diamondback moth, Plutella xylostella

“…Some full‐length and deletion constructs can induce Drosophila AMP genes in S2 cells. The induction levels were generally less than three‐fold, which were significantly lower than the in vivo inductions (Shahzad et al., ; Yang, Zhan, Ye, Yu, & Rao, ). One possible reason is due to the species‐related difference of the protein sequences.…”

Molecular characterization of a typical 2‐Cys thioredoxin peroxidase from the Asiatic rice borer Chilo suppressalis and its role in oxidative stress

“…We also noticed that the level of CsTpx3 expression was not significantly changed in response to abamectin exposure (Figure f), and transcription decreased after the initial increase following treatment with E. coli , chlorpyrifos, and lambda‐cyhalothrin (Figure c–e). A possible explanation is that many other antioxidant‐, immune‐, and/or detoxification‐related genes (e.g., CAT s, GPX s, antimicrobial peptides, ATP‐binding cassette transporters, glutathione S ‐transferases, carboxylesterases, and cytochrome P450s) may be activated by elevated stress levels, and play important roles in cellular defenses (Liao et al., ; Rao et al., ; Shi et al., ; Yang, Zhan, Ye, Yu, & Rao, ; Yu et al., ). Therefore, the function of CsTpx3 may be weakened in the antioxidant mechanism.…”

Quantitative label-free proteomic analysis reveals differentially expressed proteins in the digestive juice of resistant versus susceptible silkworm strains and their predicted impacts on BmNPV infection

“…The SP, AP and Spn-2 proteins in digestive juice were selected for western blotting analysis. Because there exists no appropriate control for digestive juice, Coomassie Blue R-250 staining was performed according to Rao et al [31]. The results show that SP was increased in resistant and susceptible strain following BmNPV infection.…”