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The Ov20 protein of the parasitic nematode Onchocerca volvulus - A structurally novel class of small helix-rich retinol-binding proteins

  • Lindsay McDermott
    ,
  • Malcolm W. Kennedy
    ,
  • Lisa H. Garside
    ,
  • Lucy E. Goodrick
    ,
  • Andrew Brass
    ,
  • Nicholas C. Price
  • University of Glasgow
    ,
  • University of Salford
    ,
  • University of Manchester
    ,
  • University of Stirling
Research Output: Contribution to journal Article Peer-review

Abstract

Ov20 is a major antigen of the parasitic nematode Onchocerca volvulus, the causative agent of river blindness in humans, and the protein is secreted into the tissue occupied by the parasite. DNA encoding Ov20 was isolated, and the protein was expressed in Escherichia coli. Fluorescence-based ligand binding assays show that the protein contains a high affinity binding site for retinol, fluorescent fatty acids (11-((5-dimethylaminonaphthalene-1-sulfonyl)amino)undecanoic acid, dansyl-DL-alpha-aminocaprylic acid, and parinaric acid) and, by competition, oleic and arachidonic acids, but not cholesterol. The fluorescence emission of dansylated fatty acids is significantly blue-shifted upon binding in comparison to similarly sized beta-sheet-rich mammalian retinol- and fatty acid-binding proteins. Secondary structure prediction algorithms indicate that a alpha-helix predominates in Ov20, possibly in a coiled coil motif, with no evidence of beta structures, and this was confirmed by circular dichroism. The protein is highly stable in solution, requiring temperatures in excess of 90 degrees C or high denaturant concentrations for unfolding. Ov20 therefore represents a novel class of small retinol-binding protein, which appears to be confined to nematodes. The retinol binding activity of Ov20 could possibly contribute to the eye defects associated with onchocerciasis and, because there is no counterpart in mammals, represents a strategic target for chemotherapy.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 29442-29448

Journal (Volume, Issue Number)

Journal of Biological Chemistry (Volume 272, Issue 47)

Publication milestones

  • Published - 21/11/1997

Publication status

Published - 21/11/1997

ISSN

0021-9258

External Publication IDs

  • handle.net: 10547/622691
  • Scopus: 0030682113

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