title: Characterization of a putative hsp70 pseudogene transcribed in protoscoleces and adult worms of Echinococcus granulosus.
abstract: Searching for hsp70 genes in Echinococcus granulosus, a divergent cytoplasmic hsp70-like sequence (EgpsiHsp70) was isolated, possessing a small truncation in the region coding for the C-terminal glycine-rich linker and EEVD-Ct motif. Southern Blot analyses of E. granulosus, and in silico analyses of E. multilocularis indicate that this truncated sequence is repeated several times in both genomes, in some cases containing clear cut features of pseudogenization. Phylogenetic analyses and comparison of surrounding regions indicate that all these copies originated by successive genomic duplications of one originally truncated copy. These copies are diverging at an increased rate compared to functional cytoplasmic hsp70 genes, and ratios of non-synonymous over synonymous substitutions rates (dN/dS) point to a relaxation of sequence constraint, suggesting that these sequences are pseudogenes. Interestingly, RT-PCR demonstrates that EgpsiHsp70 is transcribed in protoscoleces and adult individuals of E. granulosus. We suggest that this sequence does not code for a functional polypeptide, although some features are unexpected for a sequence evolving under a strictly neutral mode. Transcription could either be vestigial or have a specific, non-coding function.
authors.affiliation: Sección Bioquímica-Biología Molecular, Facultad de Ciencias, Iguá 4225, 11400, Montevideo, Uruguay. jsoto@unicit.cl
authors.forename: Uriel
authors.initials: U
authors.lastname: Koziol
authors.forename: Andrés
authors.initials: A
authors.lastname: Iriarte
authors.forename: Estela
authors.initials: E
authors.lastname: Castillo
authors.forename: Jeannette
authors.initials: J
authors.lastname: Soto
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Bello
authors.forename: Adriana
authors.initials: A
authors.lastname: Cajarville
authors.forename: Leda
authors.initials: L
authors.lastname: Roche
authors.forename: Mónica
authors.initials: M
authors.lastname: Marín
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D048209:Echinococcus granulosus / Q000235:genetics*; D048210:Echinococcus multilocularis / Q000235:genetics; D017238:Genes, Helminth; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011544:Pseudogenes; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D018840:HSP70 Heat-Shock Proteins