NUI Maynooth

NUIM ePrints and eTheses Archive

NUIM Library

Leucine aminopeptidase of the human blood flukes, Schistosoma mansoni and Schistosoma japonicum

McCarthy, Elaine and Stack, Colin and Donnelly, Sheila M. and Doyle, Sean and Mann, Victoria H. and Brindley, Paul J. and Stewart, Michael and Day, Tim A. and Maule, Aaron G. and Dalton, John P. (2005) Leucine aminopeptidase of the human blood flukes, Schistosoma mansoni and Schistosoma japonicum. International Journal of Parasitology, 34 (6). pp. 703-714.

[img] Download (544kB)

Abstract

An array of schistosome endoproteases involved in the digestion of host hemoglobin to absorbable peptides has been described, but the exoprotease responsible for catabolising these peptides to amino acids has yet to be identified. By searching the public databases we found that Schistosoma mansoni and Schistosoma japonicum express a gene encoding a member of the M17 family of leucine aminopeptidases (LAPs). A functional recombinant S. mansoni LAP produced in insect cells shared biochemical properties, including pH optimum for activity, substrate specificity and reliance on metal cations for activity, with the major aminopeptidase activity in soluble extracts of adult worms. The pH range in which the enzyme functions and the lack of a signal peptide indicate that the enzyme functions intracellularly. Immunolocalisation studies showed that the S. mansoni LAP is synthesised in the gastrodermal cells surrounding the gut lumen. Accordingly, we propose that peptides generated in the lumen of the schistosome gut are absorbed into the gastrodermal cells and are cleaved by LAP to free amino acids before being distributed to the internal tissues of the parasite. Since LAP was also localised to the surface tegument it may play an additional role in surface membrane re-modelling.

Item Type: Article
Keywords: Aminopeptidase; Proteases; Haemoglobin digestion; Parasites; Helminths; Trematodes; Schistosomes
Subjects: Science & Engineering > Biology
Item ID: 229
Depositing User: Dr. Sean Doyle
Date Deposited: 14 Jul 2005
Journal or Publication Title: International Journal of Parasitology
Publisher: Elsevier
Refereed: Yes
URI:

    Repository Staff Only(login required)

    View Item Item control page

    Document Downloads

    More statistics for this item...