Structure and binding of the complex between a C-terminally truncated hevein and chitooligosaccharides:defining the minimum hevein domain with measurable affinity

摘要

Plants respond to pathogenic attack by producing defense proteins able to bind reversibly to chitin,a structural component of fungal cell walls or invertebrate exoskeletons.A number of those defense proteins share a highly conserved Gly,Cys-rich common structural pattern organized around a four disulfide core known as hevein domain or chitin binding motif.The motif is found in lectins and wheat germ agglutinins,in addition to hevein itself or its natural variant pseudo-hevein.Its small size makes it an excellent model system for the study of protein-carbohydrate recognition.Further motivation for the study of hevein domains comes from the role of hevein as major latex allergen and from the antifungal activity of class 1 chitinases or Ac-AMP antimicrobial peptides,all of them bearing hevein motifs.In order to define the minimum hevein domain with affinity to chitin we have designed a simplified version of hevein(HEV32),developed an efficient solid phase synthesis for it,and studied its binding to chitooligosaccharides[(GlcNAc)_x]by NMR.