Glycoproteome in silkworm Bombyx mori and alteration by BmCPV infection

Abstract

The biological functions of protein glycosylation have been increasingly recognized but not yet been very well understood, especially in lower organisms. Silkworm as a model lepidopteran insect and important economic insect, has been widely studied in life science, however, the current knowledge on the glycosylation status of its proteome is not satisfactory, and little is known about how pathogenic infections could affect the glycosylation status. This study performed large scale glycosite mapping for the silkworm Bombyx mori P50 strain, and quantitatively compared with that infected with the Bombyx mori cytoplasmic polyhedrosis virus (BmCPV). Some 400 glycoproteins were mapped in the silkworm, including N- and O-glycoproteins. Upon virus infection, the glycosylation levels of 41 N-glycopeptides were significantly changed, some of them belonging to transmembrane glycoproteins. The O-glycosylation profiles were also affected. In addition, 4 BmCPV-encoded viral proteins were found to be glycosylated for the first time, including polyhedrin, P101, VP3, and the NS protein. This study drafted a silkworm protein glycosylation map and underlined the potential impact of virus infection on glycosylation. SIGNIFICANCE: This study reveals the characteristics of the glycoproteome in the silkworm strain P50, and quantitatively compared to that infected by the virus BmCPV, which underlines the impact of virus infection on the alteration of protein glycosylation in invertebrate species. Our findings add to the knowledge of the post translational modifications of this model organism, and also uncovered for the first time the glycosylation status of the viral proteins expressed by BmCPV.

Keywords: BmCPV; Bombxy mori; Glycoproteome; O-glycans; Silkworm.

Graphical abstract

Fig. 1

Characteristics of the silkworm N-glycoproteome. (a) Molecular weight distribution of silkworm N-glycoproteins in the P50 strain, (b) distribution of the number of N-glycoproteins having a particular number of N-glycosites, (c) sequence motif analysis centered on the N-glycosylation site, and (d) top10 enriched GO terms in biological processes (p < .05) for the 389 total glycoproteins identified in silkworm.

Fig. 2

Quantitative comparison between the N-glycoproteomes of the control and virus-infected groups. (a) Data discrepancy of the glycopeptide intensities within the triplicate measurement for each group, (b) GO analysis in terms of biological process for the 41 differentially regulated glycoproteins upon BmNPV infection, the heat maps of the (c) significantly downregulated and (d) significantly upregulated N-glycopeptides between the control and BmCPV-infected P50 strains.