title: Modular structure of HEL protein from Arabidopsis reveals new potential functions for PR-4 proteins.
abstract: Plants possess an innate immune system enabling them to defend themselves against pathogen attack. The accumulation of newly synthesized pathogenesis-related proteins (PRs) is one of the most studied inducible plant defence response. In this paper, we report on the characterization of a class I PR4 vacuolar protein from Arabidopsis, named AtHEL. The protein has a modular structure consisting of an N-terminal hevein-like domain (CB-HEL) and a C-terminal domain (CD-HEL) that are posttranslationally processed. Both domains show a strong antifungal activity, but they do not have chitinolitic properties. CD-HEL was found to be endowed with RNase, but not DNase activity. Molecular modeling carried out on both domains revealed that CB-HEL possesses a chitin binding site strictly conserved between hevein-type peptides and that the cavity involved in substrate interaction of CD-HEL do not show any residue substitution with respect to the orthologous wheatwin1 from wheat. Using a fishing for partners approach, CB-HEL was found to interact with a fungal fruiting body lectin. According to literature, we can hypothesize that CB-HEL could cross the pathogen hyphal membrane and that its interaction with a fungal lectin could knock out one of the weapons that the fungus uses.
authors.affiliation: Department of Ecological and Biological Sciences, University of Tuscia, Via S. Camillo de Lellis, Viterbo, Italy
authors.forename: Laura
authors.initials: L
authors.lastname: Bertini
authors.forename: Silvia
authors.initials: S
authors.lastname: Proietti
authors.forename: Maria Pia
authors.initials: MP
authors.lastname: Aleandri
authors.forename: Francesca
authors.initials: F
authors.lastname: Mondello
authors.forename: Silvia
authors.initials: S
authors.lastname: Sandini
authors.forename: Carlo
authors.initials: C
authors.lastname: Caporale
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D002686:Chitin / Q000737:chemistry / Q000378:metabolism; D048690:Fruiting Bodies, Fungal / Q000502:physiology; D005670:Fusarium / Q000187:drug effects / Q000254:growth & development; D037102:Lectins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D012260:Ribonucleases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D029681:Arabidopsis Proteins; D037102:Lectins; D010940:Plant Proteins; D011994:Recombinant Proteins; C062880:Win-1 proteins, plant; C053376:pathogenesis-related proteins, plant; D002686:Chitin; D012260:Ribonucleases