The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease

DSpace/Manakin Repository

Search OPUS


Advanced Search

Browse

My Account

Show simple item record

dc.contributor.author Lowther, J
dc.contributor.author Robinson, MW
dc.contributor.author Donnelly, SM
dc.contributor.author Xu, W
dc.contributor.author Stack, CM
dc.contributor.author Matthews, JM
dc.contributor.author Dalton, JP
dc.date.accessioned 2010-05-28T09:46:01Z
dc.date.issued 2009
dc.identifier.citation PLoS Neglected Tropical Diseases, 2009, 3 (1)
dc.identifier.other C1 en_US
dc.identifier.uri http://hdl.handle.net/10453/8872
dc.description.abstract The helminth parasite Fasciola hepatica secretes cathepsin L cysteine proteases to invade its host, migrate through tissues and digest haemoglobin, its main source of amino acids. Here we investigated the importance of pH in regulating the activity and functions of the major cathepsin L protease FheCL1. The slightly acidic pH of the parasite gut facilitates the auto-catalytic activation of FheCL1 from its inactive proFheCL1 zymogen; this process was ∼40-fold faster at pH 4.5 than at pH 7.0. Active mature FheCL1 is very stable at acidic and neutral conditions (the enzyme retained ∼45% activity when incubated at 37°C and pH 4.5 for 10 days) and displayed a broad pH range for activity peptide substrates and the protein ovalbumin, peaking between pH 5.5 and pH 7.0. This pH profile likely reflects the need for FheCL1 to function both in the parasite gut and in the host tissues. FheCL1, however, could not cleave its natural substrate Hb in the pH range pH 5.5 and pH 7.0; digestion occurred only at pH ≤4.5, which coincided with pH-induced dissociation of the Hb tetramer. Our studies indicate that the acidic pH of the parasite relaxes the Hb structure, making it susceptible to proteolysis by FheCL1. This process is enhanced by glutathione (GSH), the main reducing agent contained in red blood cells. Using mass spectrometry, we show that FheCL1 can degrade Hb to small peptides, predominantly of 4-14 residues, but cannot release free amino acids. Therefore, we suggest that Hb degradation is not completed in the gut lumen but that the resulting peptides are absorbed by the gut epithelial cells for further processing by intracellular di- and amino-peptidases to free amino acids that are distributed through the parasite tissue for protein anabolism. © 2009 Lowther et al.
dc.language eng
dc.relation.isbasedon 10.1371/journal.pntd.0000369
dc.title The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease
dc.type Journal Article
dc.parent PLoS Neglected Tropical Diseases
dc.journal.volume 1
dc.journal.volume 3
dc.journal.number 1 en_US
dc.publocation San Francisco, USA en_US
dc.identifier.startpage 1 en_US
dc.identifier.endpage 11 en_US
dc.cauo.name SCI.Faculty of Science en_US
dc.conference Verified OK en_US
dc.for 0605 Microbiology
dc.personcode 995262
dc.personcode 995261
dc.personcode 030896
dc.personcode 996591
dc.personcode 995281
dc.personcode 100777
dc.percentage 100 en_US
dc.classification.name Microbiology en_US
dc.classification.type FOR-08 en_US
dc.edition en_US
dc.custom en_US
dc.date.activity en_US
dc.location.activity ISI:000263301100017 en_US
pubs.embargo.period Not known
pubs.organisational-group /University of Technology Sydney
pubs.organisational-group /University of Technology Sydney/Faculty of Science
pubs.organisational-group /University of Technology Sydney/Strength - i3
utslib.copyright.status Open Access
utslib.copyright.date 2015-04-15 12:23:47.074767+10
pubs.consider-herdc true
utslib.collection.history School of Medical and Molecular Sciences (ID: 341)
utslib.collection.history General (ID: 2)


Files in this item

This item appears in the following Collection(s)

Show simple item record