Abstract
Pathogen-related yeast protein 1 (Pry1) is a Saccharomyces cerevisiae member of the CAP/SCP/TAPS superfamily. Although, CAP proteins have been proposed to be implicated in a number of physiological processes, such as pathogen virulence, sperm maturation andfertilization, host-pathogen interactions and defense mechanisms, the molecular mode of action of these proteins is poorly understood. CAP proteins are mostly secreted and they are stable in the extracellular space over a wide a range of conditions. All members of this superfamily contain a common CAP domain of approximately 150 amino acids, which adopts a unique α-β-α sandwich fold. We have previously shown that the yeast CAP family members act as sterol-binding and -export proteins in vivo and that the Pry proteins bind cholesterol and cholesteryl acetate in vitro. The conserved CAP domain of Pry1 is necessary and sufficient for sterol binding. Based on these observations, it is conceivable that CAP proteins exert their biological function through a common mechanism, such as binding and sequestration of sterols or related small hydrophobic compounds. Here we analyze the ligand specificity of Pry1 in more detail and show that the presence of the aliphatic isooctane side chain of the sterol but not the 3-hydroxyl group is important for binding to Pry1.
Highlights
We have previously shown that the yeast CAP family members act as sterol-binding and -export proteins in vivo and that the Pry proteins bind cholesterol and cholesteryl acetate in vitro
The CAP/SCP/TAPS superfamily of proteins (cysteine-rich secretory proteins, antigen 5 (Ag5), pathogenesis related 1 proteins (PR-1)/sperm coating proteins/Tpx-1/Ag5/PR-1/Sc7; Pfam accession number PF00188) comprises more than 4500 members in over 1500 species and family members are found in all kingdoms of life
Expression of human CAP member, CRISP2, or the Schistosoma mansoni venom allergen like protein 4, SmVAL4, in yeast rescues the sterol export defect of a pry1Δ pry2Δ double mutant and purified CRISP2 or SmVAL4 proteins bind cholesterol in vitro, indicating that cholesterol binding and export is a conserved function of diverse CAP superfamily members [4,5]
Summary
The CAP/SCP/TAPS superfamily of proteins (cysteine-rich secretory proteins, antigen 5 (Ag5), pathogenesis related 1 proteins (PR-1)/sperm coating proteins/Tpx-1/Ag5/PR-1/Sc7; Pfam accession number PF00188) comprises more than 4500 members in over 1500 species and family members are found in all kingdoms of life. Pathogen-related yeast protein 1 (Pry1) is a Saccharomyces cerevisiae member of the CAP/SCP/TAPS superfamily. We have previously shown that the yeast CAP family members act as sterol-binding and -export proteins in vivo and that the Pry proteins bind cholesterol and cholesteryl acetate in vitro.
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