In vitro and in silico analysis of signal peptides from the human blood fluke,Schistosoma mansoni

Abstract

Proteins secreted by and anchored on the surfaces of parasites are in intimate contact with host tissues. The transcriptome of infective cercariae of the blood fluke, Schistosoma mansoni, was screened using signal sequence trap to isolate cDNAs encoding predicted proteins with an N-terminal signal peptide. Twenty cDNA fragments were identified, most of which contained predicted signal peptides or transmembrane regions, including a novel putative seven-transmembrane receptor and a membrane-associated mitogen-activated protein kinase. The developmental expression pattern within different life-cycle stages ranged from ubiquitous to a transcript that was highly upregulated in the cercaria. A bioinformatics-based comparison of 100 signal peptides from each of schistosomes, humans, a parasitic nematode and Escherichia coli showed that differences in the sequence composition of signal peptides, notably the residues flanking the predicted cleavage site, might account for the negative bias exhibited in the processing of schistosome signal peptides in mammalian cells.

Cloning and characterization of an orphan seven transmembrane receptor from Schistosoma mansoni

“…Triose phosphate isomerase was used as a constitutively expressed control mRNA ( cf . Pearson et al . 2005).…”

“…Using signal sequence trapping, we identified novel membrane receptors (Smyth et al . 2003; Pearson et al . 2005), including a partial sequence encoding a putative seven transmembrane (7TM) receptor.…”

A library of cell-surface and secreted proteins fromSchistosoma mansoniidentifies early serological markers of infection

“…Extracellular antigens released by or displayed at the surface of the parasite at the initial stage of infection can be valuable early immunodiagnostic markers as they are directly exposed to the host humoral system [3]. The identification of such antigens has been aided by the sequencing and annotation of the S. mansoni genome [12] and several proteomics [13][14][15][16][17][18][19][20][21], transcriptional [22][23][24][25][26][27] and in silico analyses [28], which have identified genes expressed by the schistosomula and adult worm. Despite their value, extracellular proteins pose challenges for recombinant expression because they contain structurally important posttranslational modifications such as glycosylation and especially disulphide bonds, which are often required to produce informative antibody epitopes.…”

Identifying Schistosoma japonicum Excretory/Secretory Proteins and Their Interactions with Host Immune System

“…Using mass spectrometry hundreds of ES proteins have been identified in different developmental stages of S.mansoni [4], [5], [6], [7], [8] and S.japonicum [9], [10], [11]. Despite of that, the number of proteins already found is still very limited due to the capacity of mass spectrometry and in vitro culture.…”