title: Identification and functional characterization of a peptidoglycan recognition protein from the cotton bollworm, Helicoverpa armigera.
abstract: Peptidoglycan recognition proteins (PGRPs) specifically bind to peptidoglycans, and play crucial roles as pattern recognition receptors (PRRs) in mediating innate immune responses. In this study, we identified and characterized a PGRP (HaPGRP-D) from the cotton bollworm, Helicoverpa armigera. Sequence analysis indicated that HaPGRP-D is an amidase-type PGRP. Expression of HaPGRP-D was upregulated in the hemocytes of H. armigera larvae after injecting Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus, or chromatography beads. To test the biological activity of HaPGRP-D, purified recombinant protein was prepared. Subsequent analysis showed that rHaPGRP-D (i) could bind and agglutinate Gram-negative E. coli and Gram-positive S. aureus in a zinc-dependent manner, (ii) functioned as an amidase to degrade peptidoglycans in the presence of Zn(2+) , (iii) strongly inhibited the growth of E. coli and S. aureus in the presence of Zn(2+) , (iv) could bind to the surface of hemocytes, (v) increased the phagocytosis of E. coli cells by hemocytes in vitro, and (vi) promoted hemocyte encapsulation on chromatography beads in vitro. These results suggest that HaPGRP-D plays important roles as PRR, amidase, and opsonin in H. armigera humoral and cellular immune responses.
authors.affiliation: Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Li
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Song
authors.forename: Min
authors.initials: M
authors.lastname: Xiao
authors.forename: Jia-Lin
authors.initials: JL
authors.lastname: Wang
authors.forename: Xu-Sheng
authors.initials: XS
authors.lastname: Liu
mesh_terms: D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000276:immunology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000276:immunology*; D006434:Hemocytes / Q000378:metabolism; D007113:Immunity, Innate / Q000235:genetics*; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D010457:Peptidoglycan / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000276:immunology; D015032:Zinc
chemical_list: D002352:Carrier Proteins; D017931:DNA Primers; D010457:Peptidoglycan; C118897:peptidoglycan recognition protein; D015032:Zinc
keywords: Helicoverpa armigera; encapsulation; peptidoglycan recognition protein; phagocytosis