title: Fasciola gigantica cathepsin B5 is an acidic endo- and exopeptidase of the immature and mature parasite.
abstract: Cysteine proteases of the liver fluke Fasciola have been described as essential molecules in the infection process of the mammalian host. Destinct cathepsin Bs, which are already expressed in the metacercarial stage and released by the newly excysted juvenile are major actors in this process. Following infection their expression is stopped and the proteins will not be detectable any longer after the first month of development. On the contrary, the novel cathepsin B5 of Fasciola gigantica (FgCB5) described in this work was also found expressed in later juvenile stages and the mature worm. Like all previously described Fasciola family members it was located in the cecal epithelium of the parasite. Western blot analysis of adult antigen preparations detected procathepsin B5 in crude worm extract and in small amounts in the ES product. In support of these data, the sera of infected rabbits and mice were reactive with recombinant FgCB5 in Western blot and ELISA. Biochemical analysis of yeast-expressed FgCB5 revealed that it has properties of a lysosomal hydrolase optimized for activity at acid pH and that it is able to efficiently digest a broad spectrum of host proteins. Unlike previously characterized Fasciola family members FgCB5 carries a histidine doublet in the occluding loop equivalent to residues His110 and His111 of human mature cathepsin B and consequently showed substantial carboxydipeptidyl activity which depends on these two residues.
authors.affiliation: Faculty of Allied Health Sciences, Thammasat University, Pathumthani, Thailand.
authors.forename: Sinee
authors.initials: S
authors.lastname: Siricoon
authors.affiliation: Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Suksiri
authors.initials: S
authors.lastname: Vichasri Grams
authors.affiliation: Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Kittisak
authors.initials: K
authors.lastname: Lertwongvisarn
authors.affiliation: Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Muntana
authors.initials: M
authors.lastname: Abdullohfakeeyah
authors.affiliation: School of Applied Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Smooker
authors.affiliation: Faculty of Allied Health Sciences, Thammasat University, Pathumthani, Thailand. Electronic address: rgrams@tu.ac.th.
authors.forename: Rudi
authors.initials: R
authors.lastname: Grams
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002401:Cathepsin B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002432:Cecum / Q000201:enzymology / Q000254:growth & development; D017124:Conserved Sequence; D004150:Dipeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D005209:Fasciola / Q000201:enzymology* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006639:Histidine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000201:enzymology / Q000254:growth & development; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D004792:Enzyme Precursors; D015801:Helminth Proteins; D007527:Isoenzymes; D011994:Recombinant Proteins; D006639:Histidine; D002268:Carboxypeptidases; D004150:Dipeptidases; D002401:Cathepsin B
keywords: Autoprocessing; Cathepsin B; Cysteine protease; Fasciola gigantica; Inhibition; Proteolytic activity