Host Protein Degradation by Schistosome Parasites

Summary

Principal Investigator: James McKerrow
Abstract: PROVIDED. We hypothesize that degradation of hemoglobin and other host plasma proteins in the gut of schistosome parasites is carried out by a cascade or network of proteolytic enzymes. To map the biochemical steps involved in this pathway, we are initially focusing on two proteases: schistosome legumain (asparaginyl endopeptidase) and schistosome cathepsin B. These two proteases are thought to represent an initial zymogen activation and subsequent host protein degradation segment of the cascade. To circumvent difficulties in evaluating schistosome metabolic pathways, we are utilizing several new synthetic and biochemical techniques to dissect biologic function by "chemical knockout". The substrate specificity of both enzymes will first be mapped in detail utilizing a combination of diverse combinatorial fluorogenic peptide substrate libraries and substrate phage display. Substrate preference at the amino acid positions P3-P3' will give clues to potential protein substrate cleavage sites that can be validated by direct analysis of protein degradation products. Using 2D gel electrophoresis and mass spectrometry, major natural substrates of cathepsin B will be confirmed by analyzing regurgitant proteins from adult worm guts for protein profile changes in the presence or absence of cathepsin B or legumain-specific inhibitors. Preliminary studies have confirmed the feasibility of this approach, and identified several putative plasma protein substrates were identified. Cleavage patterns of these substrates can now be compared to the predicted substrate specificity of the proteases being evaluated. To ensure we can carry out chemical knockout with appropriate specificity, diverse combinatorial inhibitor libraries have been produced for both enzymes, and will next be screened for protease- specific inhibitors that can be used to confirm expected, or uncover unexpected biological functions. Recently developed radiolabeled or fluorescently "tagged" inhibitors will also be used to identify, localize, and quantitate both enzymes in schistosome extracts, gut regurgitant material, and gut epithelium. The results of these studies should have import not only in unraveling the pathway of schistosome blood protein digestions, but providing a technical approach to aid investigators studying the similar cascades recently identified in Fasciola and Haemonchus and likely to be present in other blood feeding nematode and trematode parasites.
Funding Period: 2003-07-01 - 2008-12-31
more information: NIH RePORT

Top Publications

  1. ncbi Multiple cathepsin B isoforms in schistosomula of Trichobilharzia regenti: identification, characterisation and putative role in migration and nutrition
    Jan Dvorak
    Department of Parasitology, Faculty of Science, Charles University, Vinicna 7, CZ 12844 Prague, Czech Republic
    Int J Parasitol 35:895-910. 2005
  2. ncbi A multienzyme network functions in intestinal protein digestion by a platyhelminth parasite
    Melaine Delcroix
    Department of Pathology, Tropical Disease Research Unit and Sandler Center for Basic Research in Parasitic Diseases, University of California, San Francisco, California 94158, USA
    J Biol Chem 281:39316-29. 2006
  3. pmc Schistosomiasis mansoni: novel chemotherapy using a cysteine protease inhibitor
    Maha Hamadien Abdulla
    Sandler Center for Basic Research in Parasitic Diseases, California Institute for Quantitative Biomedical Research, University of California San Francisco, San Francisco, California, United States of America
    PLoS Med 4:e14. 2007
  4. pmc Proteomic analysis of adult S. mansoni gut contents
    Melaine Delcroix
    Sandler Center for Basic Research in Parasitic Diseases, California Institute for Quantitative Biomedical Research QB3, 1700 4th St, University of California, San Francisco, CA 94158 2330, USA
    Mol Biochem Parasitol 154:95-7. 2007
  5. pmc Gene expression patterns during adaptation of a helminth parasite to different environmental niches
    Emmitt R Jolly
    California Institute for Quantitative Biomedical Research QB3 of the University of California, San Francisco, San Francisco, CA 94158 USA
    Genome Biol 8:R65. 2007
  6. ncbi Differential use of protease families for invasion by schistosome cercariae
    Jan Dvorak
    Sandler Center for Basic Research in Parasitic Diseases, California Institute for Quantitative Biomedical Research QB3, 1700 4th Street, University of California, San Francisco, CA 94158 2550, USA
    Biochimie 90:345-58. 2008
  7. ncbi Proteases in parasitic diseases
    James H McKerrow
    Department of Pathology, Sandler Center, University of California, San Francisco, California 94143, USA
    Annu Rev Pathol 1:497-536. 2006
  8. pmc Structural and functional relationships in the virulence-associated cathepsin L proteases of the parasitic liver fluke, Fasciola hepatica
    Colin M Stack
    Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, Sydney, New South Wales 2007, Australia
    J Biol Chem 283:9896-908. 2008
  9. ncbi Aza-peptidyl Michael acceptors. A new class of potent and selective inhibitors of asparaginyl endopeptidases (legumains) from evolutionarily diverse pathogens
    Marion G Götz
    School of Chemistry and Biochemistry and the Petit Institute for Bioscience and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332 0400, USA
    J Med Chem 51:2816-32. 2008

Scientific Experts

  • James McKerrow
  • Emmitt R Jolly
  • Conor R Caffrey
  • Jan Dvorak
  • Melaine Delcroix
  • Mohammed Sajid
  • Marion G Götz
  • Colin M Stack
  • Amritha Seshaadri
  • Elizabeth Hansell
  • Kee Chong Lim
  • Maha Hamadien Abdulla
  • Mahmoud Bahgat
  • Ivy Hsieh
  • Katalin F Medzihradszky
  • Daniel Sojka
  • Charles S Craik
  • Petr Kopacek
  • Sheila M Donnelly
  • Jonathan Lowther
  • Mark W Robinson
  • Susan T Mashiyama
  • Peter R Collins
  • James C Powers
  • Sebastian R Geiger
  • Weibo Xu
  • Bryony Mackenzie
  • Giselle M Knudsen
  • Simon Braschi
  • Karen Ellis James
  • Rachel Marion
  • Linda S Brinen
  • John P Dalton
  • Jose F Tort
  • Patricia C Babbitt
  • Katalin Medzihradsky
  • Richard D Fetter
  • Colette Dissous
  • Kee C Lim
  • Libor Mikes
  • Martin Pospisek
  • Andrej Sali
  • Petr Horak
  • Andrea Rossi
  • Miroslava Sedinová
  • Vaclav Vopalensky

Detail Information

Publications9

  1. ncbi Multiple cathepsin B isoforms in schistosomula of Trichobilharzia regenti: identification, characterisation and putative role in migration and nutrition
    Jan Dvorak
    Department of Parasitology, Faculty of Science, Charles University, Vinicna 7, CZ 12844 Prague, Czech Republic
    Int J Parasitol 35:895-910. 2005
    ..Also, both isoforms degraded myelin basic protein, the major protein component of nervous tissue, but were inefficient against hemoglobin, thus supporting the adaptation of T. regenti gut peptidases to parasitism of host nervous tissue...
  2. ncbi A multienzyme network functions in intestinal protein digestion by a platyhelminth parasite
    Melaine Delcroix
    Department of Pathology, Tropical Disease Research Unit and Sandler Center for Basic Research in Parasitic Diseases, University of California, San Francisco, California 94158, USA
    J Biol Chem 281:39316-29. 2006
    ..It also provides insights into which of these proteases are logical targets for development of chemotherapy for schistosomiasis, a major global health problem...
  3. pmc Schistosomiasis mansoni: novel chemotherapy using a cysteine protease inhibitor
    Maha Hamadien Abdulla
    Sandler Center for Basic Research in Parasitic Diseases, California Institute for Quantitative Biomedical Research, University of California San Francisco, San Francisco, California, United States of America
    PLoS Med 4:e14. 2007
    ..Due to the lack of a vaccine, patient therapy is heavily reliant on chemotherapy with praziquantel as the World Health Organization-recommended drug, but concerns over drug resistance encourage the search for new drug leads...
  4. pmc Proteomic analysis of adult S. mansoni gut contents
    Melaine Delcroix
    Sandler Center for Basic Research in Parasitic Diseases, California Institute for Quantitative Biomedical Research QB3, 1700 4th St, University of California, San Francisco, CA 94158 2330, USA
    Mol Biochem Parasitol 154:95-7. 2007
  5. pmc Gene expression patterns during adaptation of a helminth parasite to different environmental niches
    Emmitt R Jolly
    California Institute for Quantitative Biomedical Research QB3 of the University of California, San Francisco, San Francisco, CA 94158 USA
    Genome Biol 8:R65. 2007
    ..We report a global transcriptional analysis of how this parasite alters gene regulation to adapt to three distinct environments...
  6. ncbi Differential use of protease families for invasion by schistosome cercariae
    Jan Dvorak
    Sandler Center for Basic Research in Parasitic Diseases, California Institute for Quantitative Biomedical Research QB3, 1700 4th Street, University of California, San Francisco, CA 94158 2550, USA
    Biochimie 90:345-58. 2008
    ..Computational analysis of serine protease phylogeny revealed an extraordinarily distant relationship between S. mansoni serine proteases and other members of the Clan PA family S1 proteases...
  7. ncbi Proteases in parasitic diseases
    James H McKerrow
    Department of Pathology, Sandler Center, University of California, San Francisco, California 94143, USA
    Annu Rev Pathol 1:497-536. 2006
    ....
  8. pmc Structural and functional relationships in the virulence-associated cathepsin L proteases of the parasitic liver fluke, Fasciola hepatica
    Colin M Stack
    Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, Sydney, New South Wales 2007, Australia
    J Biol Chem 283:9896-908. 2008
    ..The emergence of a specialized collagenolytic function in Fasciola likely contributes to the success of this tissue-invasive parasite...
  9. ncbi Aza-peptidyl Michael acceptors. A new class of potent and selective inhibitors of asparaginyl endopeptidases (legumains) from evolutionarily diverse pathogens
    Marion G Götz
    School of Chemistry and Biochemistry and the Petit Institute for Bioscience and Bioengineering, Georgia Institute of Technology, Atlanta, Georgia 30332 0400, USA
    J Med Chem 51:2816-32. 2008
    ..The preferred P1' residues have aromatic substituents. Aza-asparaginyl Michael acceptors react with thiols, which provides insight into the mechanism of their inhibition of asparaginyl endopeptidases...