The pathogen-related yeast protein Pry1, a member of the CAP protein superfamily, is a fatty acid-binding protein

J Biol Chem. 2017 May 19;292(20):8304-8314. doi: 10.1074/jbc.M117.781880. Epub 2017 Apr 1.

Abstract

Members of the CAP superfamily (cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins), also known as SCP superfamily (sperm-coating proteins), have been implicated in many physiological processes, including immune defenses, venom toxicity, and sperm maturation. Their mode of action, however, remains poorly understood. Three proteins of the CAP superfamily, Pry1, -2, and -3 (pathogen related in yeast), are encoded in the Saccharomyces cerevisiae genome. We have shown previously that Pry1 binds cholesterol in vitro and that Pry function is required for sterol secretion in yeast cells, indicating that members of this superfamily may generally bind sterols or related small hydrophobic compounds. On the other hand, tablysin-15, a CAP protein from the horsefly Tabanus yao, has been shown to bind leukotrienes and free fatty acids in vitro Therefore, here we assessed whether the yeast Pry1 protein binds fatty acids. Computational modeling and site-directed mutagenesis indicated that the mode of fatty acid binding is conserved between tablysin-15 and Pry1. Pry1 bound fatty acids with micromolar affinity in vitro, and its function was essential for fatty acid export in cells lacking the acyl-CoA synthetases Faa1 and Faa4. Fatty acid binding of Pry1 is independent of its capacity to bind sterols, and the two sterol- and fatty acid-binding sites are nonoverlapping. These results indicate that some CAP family members, such as Pry1, can bind different lipids, particularly sterols and fatty acids, at distinct binding sites, suggesting that the CAP domain may serve as a stable, secreted protein domain that can accommodate multiple ligand-binding sites.

Keywords: CAP protein family; Saccharomyces cerevisiae; acyl-CoA synthetase; cholesterol; fatty acid; fatty acid binding protein; fatty acid transport; secretion; sterol.

MeSH terms

  • Acyl Coenzyme A / chemistry
  • Acyl Coenzyme A / genetics
  • Acyl Coenzyme A / metabolism
  • Coenzyme A Ligases / chemistry
  • Coenzyme A Ligases / genetics
  • Coenzyme A Ligases / metabolism
  • Computer Simulation
  • Fatty Acid-Binding Proteins / chemistry
  • Fatty Acid-Binding Proteins / genetics
  • Fatty Acid-Binding Proteins / metabolism*
  • Microfilament Proteins / chemistry
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Mutagenesis, Site-Directed
  • Protein Domains
  • Saccharomyces cerevisiae / chemistry
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*

Substances

  • Acyl Coenzyme A
  • Fatty Acid-Binding Proteins
  • Microfilament Proteins
  • Pry1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Coenzyme A Ligases
  • Faa1 protein, S cerevisiae
  • FAA4 protein, S cerevisiae