Characterisation of a fatty acid and retinol binding protein orthologue from the hookworm Ancylostoma ceylanicum

Abstract

Hookworms, bloodfeeding intestinal nematodes, infect nearly one billion people in resource limited countries and are a leading cause of anemia and malnutrition. Like other nematodes, hookworms lack the capacity to synthesize essential fatty acids de novo and therefore must acquire those from exogenous sources. The cDNA corresponding to a putative Ancylostoma ceylanicum fatty acid and retinol binding protein-1 (AceFAR-1) was amplified from adult hookworm mRNA. Studies using quantitative reverse transcriptase real time-PCR demonstrate that AceFAR-1 transcripts are most abundant in the earliest developmental stages of the parasite, and greater in females than males. Using in vitro assays, the recombinant AceFAR-1 (rAceFAR-1) was shown to bind individual fatty acids with equilibrium dissociation constants in the low micromolar range. The pattern of fatty acid uptake by live adult worms cultured ex vivo was similar to the in vitro binding profile of rAceFAR-1, raising the possibility that the native protein may be involved in acquisition of fatty acids by A. ceylanicum. Animals vaccinated orally with rAceFAR-1 and the mucosal adjuvant cholera toxin exhibited a statistically significant (40-47%) reduction in intestinal worm burden compared with controls immunized with antigen or adjuvant alone. Together, these data suggest a potential role for AceFAR-1 in hookworm biology, making it a potentially valuable target for drug and vaccine development.

The Potential Role of Binding Proteins in Human Parasitic Infections: An In-Depth Look at the Novel Family of Nematode-Specific Fatty Acid and Retinol Binding Proteins

“…Based on secondary structure analysis, the structure of FAR proteins are clearly unlike that of any family of lipid-binding proteins, and also structurally distinct from proteins known from any organisms-from bacteria to plants to humans, increasing the possibility that they may present useful targets for drug development [20].…”

“…Such an expansion of the analysis to include additional temperatures may be quite relevant, as previous research has demonstrated significant variation in the binding affinities of various proteins to their ligands with regard to environmental temperature [37], and nematodespecific FAR proteins have been shown to be heat-stable [13,20]. Given that plant-parasitic nematodes are much more prevalent during warmer seasons and in tropical climates [38][39][40] and that animal parasites would, by their nature, inhabit warmer environments, it seems possible that FAR studies conducted to date, at 20°C, may not accurately reflect the binding properties of this family of protein in vivo.…”

Structural characterization and localization analysis of the root-knot nematode Meloidogyne javanica fatty acid and retinol binding protein (Mj-FAR-1)

“…These molecules have important functions as energy sources and are used in the metabolic and developmental processes of embryogenesis, glycoprotein synthesis, growth and cellular differentiation (Kennedy 2000;McDermott et al 1999). Based on secondary-structure analysis, the structure of FAR proteins is clearly unlike that of any family of lipid-binding proteins (Fairfax et al 2009). FAR proteins are structurally distinct,~20-kDa alphahelix-rich lipid-binding proteins that do not derive from larger polyproteins Prior et al 2001).…”

“…Interestingly, group A has the highest sequence identity to FAR proteins from parasitic nematodes, among them the plant parasitic FAR proteins of Globodera pallida (Gp-FAR-1), Meloidogyne javanica (Mj-FAR-1) and Aphelenchoides besseyi (Ab-FAR-1) (Cheng et al 2013;Iberkleid et al 2013;Prior et al 2001). FAR proteins have also been extensively found in parasitic nematodes of humans and animals, including Ancylostoma caninum, Brugia malayi, Brugia pahangi, Ancylostoma ceylanicum, Acanthocheilonema viteae, Ascaris suum, Heligmosomoides polygyrus, Onchocerca gutturosa, Onchocerca dukei, Onchocerca ochengi, Loa loa, Wuchereria bancrofti, and Litomosoides sigmodontis (Basavaraju et al 2003;Bath et al 2009;Fairfax et al 2009;Garofalo et al 2002;Mei et al 1997;Nirmalan et al 1999). Studies on animal-parasitic nematodes have indicated that they all belong to two major clusters and share high sequence similarity (79-100 %) (Marchler-Bauer et al 2005).…”

In vitro biological control of infective larvae of Ancylostoma ceylanicum

“…O fungo D. flagrans (AC001) apresentou atividade predatória sobre as L 3 de A. ceylanicum após o trânsito pelo trato gastrintestinal de hamsters. Além disso, foi observada uma diferença significativa nos percentuais obtidos de cada horário em relação ao numero de L 3 recuperadas (P < 0,01 The role of pet animals (dogs and cats) as reservoirs of potentially zoonotic nematodes has been recognized as a worldwide public health problem (FAIRFAX et al, 2009). Prominent among these nematodes is the genus Ancylostoma, which includes several species (A. caninum, A. braziliense and A. ceylanicum).…”