Characterization of a Caenorhabditis elegans glc seven-like phosphatase (gsp) orthologue from Haemonchus contortus (Nematoda)

Abstract

A full-length complementary DNA (cDNA; designated Hc-stp-1) encoding a serine/threonine phosphatase (Hc-STP-1) was isolated from Haemonchus contortus, a strongylid nematode parasite of small ruminants. Hc-stp-1 was shown to be transcribed in males of both adults and fourth-stage larvae, but not in females, early larval stages or eggs. The full-length gene (2854 bp) contained ten exons and nine introns, and encoded a cDNA of 951 bp. Comparisons of the conceptually translated protein (316 amino acids, estimated at approximately 35 kDa) with serine/threonine phosphatases (STPs) from other organisms revealed the presence of the conserved motif LRGNHE. Structural analysis, by comparative modelling, confirmed strict conservation of residues and features involved in catalytic activity, and variation in the ligand-binding interface. Phylogenetic analysis of amino acid sequence data revealed that Hc-STP-1 clustered with STPs from other nematodes (including Caenorhabditis elegans, Trichostrongylus vitrinus, Oesophagostomum dentatum, Ascaris suum and Brugia malayi) to the exclusion of STPs from other organisms. The protein was inferred to be most closely related to the PP1 class of STPs of C. elegans, within a group containing STPs encoded, amongst others, by the genes gsp-3 and gsp-4 in this free-living nematode. The functions of proteins GSP-3 and GSP-4 are known to be central to spermatogenesis and other male-specific processes in C. elegans. The findings from the present and previous studies support the proposal that Hc-stp-1 and its product play a significant role in reproductive and/or developmental processes in maturing or adult male H. contortus.