Characterisation of a secretory serine protease inhibitor (SjB6) from Schistosoma japonicum

Molehin, Adebayo J., Gobert, Geoffrey N., Driguez, Patrick. and McManus, Donald P. (2014) Characterisation of a secretory serine protease inhibitor (SjB6) from Schistosoma japonicum. Parasites and Vectors, 7 1: . doi:10.1186/1756-3305-7-330

Author Molehin, Adebayo J.
Gobert, Geoffrey N.
Driguez, Patrick.
McManus, Donald P.
Title Characterisation of a secretory serine protease inhibitor (SjB6) from Schistosoma japonicum
Formatted title
Characterisation of a secretory serine protease inhibitor (SjB6) from Schistosoma japonicum
Journal name Parasites and Vectors   Check publisher's open access policy
ISSN 1756-3305
Publication date 2014-07-14
Year available 2014
Sub-type Article (original research)
DOI 10.1186/1756-3305-7-330
Open Access Status DOI
Volume 7
Issue 1
Total pages 12
Place of publication London, United Kingdom
Publisher BioMed Central
Collection year 2015
Language eng
Formatted abstract
Proteins belonging to the serine protease inhibitor (serpin) superfamily play essential physiological roles in many organisms. In pathogens, serpins are thought to have evolved specifically to limit host immune responses by interfering with the host immune-stimulatory signals. Serpins are less well characterised in parasitic helminths, although some are thought to be involved in mechanisms associated with host immune modulation. In this study, we cloned and partially characterised a secretory serpin from Schistosoma japonicum termed SjB6, these findings provide the basis for possible functional roles.

SjB6 gene was identified through database mining of our previously published microarray data, cloned and detailed sequence and structural analysis and comparative modelling carried out using various bioinformatics and proteomics tools. Gene transcriptional profiling was determined by real-time PCR and the expression of native protein determined by immunoblotting. An immunological profile of the recombinant protein produced in insect cells was determined by ELISA.

SjB6 contains an open reading frame of 1160 base pairs that encodes a protein of 387 amino acid residues. Detailed sequence analysis, comparative modelling and structural-based alignment revealed that SjB6 contains the essential structural motifs and consensus secondary structures typical of inhibitory serpins. The presence of an N-terminal signal sequence indicated that SjB6 is a secretory protein. Real-time data indicated that SjB6 is expressed exclusively in the intra-mammalian stage of the parasite life cycle with its highest expression levels in the egg stage (p < 0.0001). The native protein is approximately 60 kDa in size and recombinant SjB6 (rSjB6) was recognised strongly by sera from rats experimentally infected with S. japonicum.

The significantly high expression of SjB6 in schistosome eggs, when compared to other life cycle stages, suggests a possible association with disease pathology, while the strong reactivity of sera from experimentally infected rats against rSjB6 suggests that native SjB6 is released into host tissue and induces an immune response. This study presents a comprehensive demonstration of sequence and structural-based analysis of a secretory serpin from a trematode and suggests SjB6 may be associated with important functional roles in S. japonicum, particularly in parasite modulation of the host microenvironment.
Keyword Schistosoma japonicum
Host-parasite interaction
Structural analysis
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Article ID: 7:330

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Public Health Publications
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