The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease.
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 Fhe...
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ftdoajarticles:oai:doaj.org/article:50ca6e8f1bc54096ae780fbbc94fd6ae 2023-05-15T15:14:21+02:00 The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. Jonathan Lowther Mark W Robinson Sheila M Donnelly Weibo Xu Colin M Stack Jacqueline M Matthews John P Dalton 2009-01-01T00:00:00Z https://doi.org/10.1371/journal.pntd.0000369 https://doaj.org/article/50ca6e8f1bc54096ae780fbbc94fd6ae EN eng Public Library of Science (PLoS) http://europepmc.org/articles/PMC2621350?pdf=render https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 1935-2727 1935-2735 doi:10.1371/journal.pntd.0000369 https://doaj.org/article/50ca6e8f1bc54096ae780fbbc94fd6ae PLoS Neglected Tropical Diseases, Vol 3, Iss 1, p e369 (2009) Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 article 2009 ftdoajarticles https://doi.org/10.1371/journal.pntd.0000369 2022-12-31T01:33:07Z 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 approximately 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 approximately 45% activity when incubated at 37 degrees 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. Article in Journal/Newspaper Arctic Directory of Open Access Journals: DOAJ Articles Arctic PLoS Neglected Tropical Diseases 3 1 e369 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
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Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 Jonathan Lowther Mark W Robinson Sheila M Donnelly Weibo Xu Colin M Stack Jacqueline M Matthews John P Dalton The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. |
topic_facet |
Arctic medicine. Tropical medicine RC955-962 Public aspects of medicine RA1-1270 |
description |
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 approximately 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 approximately 45% activity when incubated at 37 degrees 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. |
format |
Article in Journal/Newspaper |
author |
Jonathan Lowther Mark W Robinson Sheila M Donnelly Weibo Xu Colin M Stack Jacqueline M Matthews John P Dalton |
author_facet |
Jonathan Lowther Mark W Robinson Sheila M Donnelly Weibo Xu Colin M Stack Jacqueline M Matthews John P Dalton |
author_sort |
Jonathan Lowther |
title |
The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. |
title_short |
The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. |
title_full |
The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. |
title_fullStr |
The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. |
title_full_unstemmed |
The importance of pH in regulating the function of the Fasciola hepatica cathepsin L1 cysteine protease. |
title_sort |
importance of ph in regulating the function of the fasciola hepatica cathepsin l1 cysteine protease. |
publisher |
Public Library of Science (PLoS) |
publishDate |
2009 |
url |
https://doi.org/10.1371/journal.pntd.0000369 https://doaj.org/article/50ca6e8f1bc54096ae780fbbc94fd6ae |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
PLoS Neglected Tropical Diseases, Vol 3, Iss 1, p e369 (2009) |
op_relation |
http://europepmc.org/articles/PMC2621350?pdf=render https://doaj.org/toc/1935-2727 https://doaj.org/toc/1935-2735 1935-2727 1935-2735 doi:10.1371/journal.pntd.0000369 https://doaj.org/article/50ca6e8f1bc54096ae780fbbc94fd6ae |
op_doi |
https://doi.org/10.1371/journal.pntd.0000369 |
container_title |
PLoS Neglected Tropical Diseases |
container_volume |
3 |
container_issue |
1 |
container_start_page |
e369 |
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1766344813533200384 |