Structural and functional aspects of PR-10 proteins

Physical, chemical and biological stress factors, such as microbial infection, upregulate the transcription levels of a number of plant genes, coding for the so-called PR (pathogenesis-related) proteins. For PR proteins of class-10 (PR-10), the biological function remains unclear, despite two decades of scientific research. PR-10 proteins have a wide distribution throughout the plant kingdom and this class members share the size and secondary structure organization. Throughout the years, we and other groups have determined the structures of a number of PR-10 proteins, both in the crystalline state by X-ray diffraction, and in solution by NMR spectroscopy. Despite the accumulating structural information, our understanding of PR-10 function is still limited. PR-10 proteins are rather small (~160 amino acids) with a fold consisting of three α-helices and seven antiparallel β-strands. These structural elements enclose a large hydrophobic cavity that is most likely the key to their functional relevance. Also, the outer surface of these proteins is of extreme interest, as epitopes from a PR-10 subclass cause allergic reactions in humans. © 2013 The Authors Journal compilation © 2013 FEBS