Protein phosphorylation networks in spargana of Spirometra erinaceieuropaei revealed by phosphoproteomic analysis

Abstract

Background: Sparganosis caused by Spirometra erinaceieuropaei spargana is a zoonotic parasitic infection that has been reported in many countries, including China, Japan, Thailand and Korea, as well as European countries and the USA. The biological and clinical significance of the parasite have previously been reported. Although the genomic and transcriptomic analysis of S. erinaceieuropaei provided insightful views about the development and pathogenesis of this species, little knowledge has been acquired in terms of post-translational regulation that is essential for parasite growth, development and reproduction. Here, we performed site-specific phosphoproteomic profiling, with an aim to obtain primary information about the global phosphorylation status of spargana.

Results: A total of 3228 phosphopeptides and 3461 phosphorylation sites were identified in 1758 spargana proteins. The annotated phosphoproteins were involved in a variety of biological pathways, including cellular (28%), metabolic (20%) and single-organism (17%) processes. The functional enrichment of phosphopeptides by Gene Ontology analysis indicated that most spargana phosphoproteins were related to the cytoskeleton cellular compartment, signaling molecular function, and a variety of biological processes, including a molecular function regulator, guanyl-nucleotide exchange factor activity, protein kinase activities, and calcium ion binding. The highly enriched pathways of phosphorylation proteins include the phosphatidylinositol signaling system, phagosome, endocytosis, inositol phosphate metabolism, terpenoid backbone biosynthesis, and peroxisome. Domain analysis identified an EF-hand domain and pleckstrin homology domain among the key domains.

Conclusions: To our knowledge, this study performed the first global phosphoproteomic analysis of S. erinaceieuropaei. The dataset reported herein provides a valuable resource for future studies on the signaling pathways of this important zoonotic parasite.

Keywords: IMAC; Mass spectrometry; Phosphoproteome; Spargana; Spirometra erinaceieuropaei.

Fig. 1

General description of S. erinaceieuropaei spargana phosphoproteome data. a Pie chart representation of the distribution of identified phosphorylation sites. b GO term distribution of spargana phosphoproteins in three categories. GO annotation and categorization were performed using Blast2GO

Fig. 2

GO enrichment analysis of the phosphoproteins. The GO analysis of the phosphoproteins falls into the following GO categories: cellular component, biological process and molecular function

Fig. 3

Phosphorylation motif enrichment in S. erinaceieuropaei spargana. a Motif enrichment heat maps of the upstream and downstream amino acids of all identified phosphorylation modification sites (red indicates that the amino acid is significantly enriched near the modification site; green indicates that the amino acid is significantly reduced near the modification site). b Phosphopeptides were analyzed using motif-x webserver. The top 4 enriched motifs in phosphoserine (left) and phosphothreonine (right)

Fig. 4

Enrichment analysis of GO (a), KEGG (b) and domains analysis (c) of S. erinaceieuropaei spargana phosphoproteome. Cluster membership were visualized by a heat map using the “heatmap.2” function in the gplots package in R