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Accelerated evolution of schistosome genes coding for proteins located at the host-parasite interface
Gisele S Philippsen1, R Alan Wilson2, Ricardo DeMarco3
1Departamento de Física e Ciência Interdisciplinar, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.
Genome Biology and Evolution
|January 9, 2015
Summary
Schistosome micro-exon gene (MEG) and venom allergen-like (VAL) proteins rapidly evolve due to host immune pressure. This immune evasion strategy involves gene expansion, aiding parasite survival.
Area of Science:
- Parasitology
- Evolutionary Biology
- Immunology
Background:
- Schistosome proteins at the host-parasite interface are crucial for immune evasion.
- Micro-exon gene (MEG) and venom allergen-like (VAL) proteins are hypothesized key players in host-parasite molecular interactions.
Purpose of the Study:
- To investigate the evolutionary dynamics of MEG and VAL protein families in schistosomes.
- To understand the role of host immune pressure in shaping these protein families.
Main Methods:
- Phylogenetic and structural analysis of MEG and VAL genes.
- Comparative analysis of synonymous (dN) and nonsynonymous (dS) substitution rates.
- Examination of gene expansion mechanisms, including transposable elements.
- Analysis of paralog genes and their exposure to the host immune system.
Main Results:
- Species-specific expansion of MEG and VAL gene families occurred independently in different schistosome species.
- Transposable elements facilitate gene number expansion in MEG and VAL families in Schistosoma mansoni.
- Higher dN/dS ratios were observed in MEG and VAL genes compared to control secreted proteins, indicating positive selection.
- Exposure to the host immune system drives higher dN/dS values in these genes.
Conclusions:
- Schistosome MEG and VAL genes exhibit rapid evolution, likely driven by host immune system pressure.
- Gene expansion and accelerated evolution are key mechanisms for schistosome immune evasion.
- These findings have implications for understanding schistosome biology and developing control strategies.
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