Signal sequence analysis of expressed sequence tags from the nematode Nippostrongylus brasiliensisand the evolution of secreted proteins in parasitesReport as inadecuate




Signal sequence analysis of expressed sequence tags from the nematode Nippostrongylus brasiliensisand the evolution of secreted proteins in parasites - Download this document for free, or read online. Document in PDF available to download.

Genome Biology

, 5:R39

First Online: 18 May 2004Received: 30 December 2003Revised: 14 April 2004Accepted: 29 April 2004

Abstract

BackgroundParasitism is a highly successful mode of life and one that requires suites of gene adaptations to permit survival within a potentially hostile host. Among such adaptations is the secretion of proteins capable of modifying or manipulating the host environment. Nippostrongylus brasiliensis is a well-studied model nematode parasite of rodents, which secretes products known to modulate host immunity.

ResultsTaking a genomic approach to characterize potential secreted products, we analyzed expressed sequence tag EST sequences for putative amino-terminal secretory signals. We sequenced ESTs from a cDNA library constructed by oligo-capping to select full-length cDNAs, as well as from conventional cDNA libraries. SignalP analysis was applied to predicted open reading frames, to identify potential signal peptides and anchors. Among 1,234 ESTs, 197 ~16% contain predicted 5- signal sequences, with 176 classified as conventional signal peptides and 21 as signal anchors. ESTs cluster into 742 distinct genes, of which 135 18% bear predicted signal-sequence coding regions. Comparisons of clusters with homologs from Caenorhabditis elegans and more distantly related organisms reveal that the majority 65% at P < e of signal peptide-bearing sequences from N. brasiliensis show no similarity to previously reported genes, and less than 10% align to conserved genes recorded outside the phylum Nematoda. Of all novel sequences identified, 32% contained predicted signal peptides, whereas this was the case for only 3.4% of conserved genes with sequence homologies beyond the Nematoda.

ConclusionsThese results indicate that secreted proteins may be undergoing accelerated evolution, either because of relaxed functional constraints, or in response to stronger selective pressure from host immunity.

Electronic supplementary materialThe online version of this article doi:10.1186-gb-2004-5-6-r39 contains supplementary material, which is available to authorized users.

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Author: Yvonne M Harcus - John Parkinson - Cecilia Fernández - Jennifer Daub - Murray E Selkirk - Mark L Blaxter - Rick M Maiz

Source: https://link.springer.com/



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