Sequence-divergent units of the ABA-1 polyprotein array of the nematode Ascaris suum have similar fatty-acid- and retinol-binding properties but different binding-site environments
McDermott, Lindsay C.
Price, Nicholas C.
Kelly, Sharon M.
Kennedy, Malcolm W.
MetadataShow full item record
AbstractPolyproteins comprise long polypeptides that are post-translationally cleaved into proteins of different function, or tandemly repetitive polypeptides which are processed into multiple versions of proteins which are presumed to have the same function. In the latter case the individual units of the polyprotein can differ substantially in sequence. Identity of function between the different units therefore cannot be assumed. Here we have examined the ABA-1 polyprotein allergen of the parasitic nematode Ascaris suum and found it to contain units which show a 50% difference in amino acid sequence. The parasite therefore produces at least two radically different forms of the allergen encoded within the polyprotein array. In fluorescence-based ligand-binding assays, recombinant polypeptides representing the two forms (designated ABA-1A1 and ABA-1B1) showed similar binding affinities for a range of fluorescent active-site probes [retinol, dansylundecanoic acid, dansyl-DL-alpha-amino-octanoic acid, cis-parinaric acid (cPnA)] and for the non-specific hydrophobic surface probe 8-anilinonaphthalene-1-sulphonic acid. However, the molecular environments in the active sites are markedly different, as indicated by disparate fluorescence emission peaks and intensities of bound probes. CD showed that the proteins have similar secondary structures but differ in susceptibility to chemical denaturation/unfolding by guanidinium chloride. Both retain a single conserved tryptophan residue in a characteristic non-polar environment, as revealed by extreme fluorescence blue shift. Thus the gross differences in sequence of the two proteins are not reflected in their ligand-binding specificities but in their binding-site environments.
CitationMoore J, McDermott L, Price NC, Kelly SM, Cooper A, Kennedy MW (1999) 'Sequence-divergent units of the ABA-1 polyprotein array of the nematode Ascaris suum have similar fatty-acid- and retinol-binding properties but different binding-site environments', Biochemical Journal, 340 (), pp.337-343.
- The ABA-1 allergen of the parasitic nematode Ascaris suum: fatty acid and retinoid binding function and structural characterization.
- Authors: Kennedy MW, Brass A, McCruden AB, Price NC, Kelly SM, Cooper A
- Issue date: 1995 May 23
- The ABA-1 allergen of Ascaris lumbricoides: sequence polymorphism, stage and tissue-specific expression, lipid binding function, and protein biophysical properties.
- Authors: Xia Y, Spence HJ, Moore J, Heaney N, McDermott L, Cooper A, Watson DG, Mei B, Komuniecki R, Kennedy MW
- Issue date: 2000 Feb
- Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of Ascaris reveals a novel fold and two discrete lipid-binding sites.
- Authors: Meenan NA, Ball G, Bromek K, Uhrín D, Cooper A, Kennedy MW, Smith BO
- Issue date: 2011 Apr 19
- Mutagenic and chemical modification of the ABA-1 allergen of the nematode Ascaris: consequences for structure and lipid binding properties.
- Authors: McDermott L, Moore J, Brass A, Price NC, Kelly SM, Cooper A, Kennedy MW
- Issue date: 2001 Aug 21
- How helminth lipid-binding proteins offload their ligands to membranes: differential mechanisms of fatty acid transfer by the ABA-1 polyprotein allergen and Ov-FAR-1 proteins of nematodes and Sj-FABPc of schistosomes.
- Authors: McDermott L, Kennedy MW, McManus DP, Bradley JE, Cooper A, Storch J
- Issue date: 2002 May 28