Structure
Volume 4, Issue 12, 15 December 1996, Pages 1429-1439
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Research Article
Crystal structure of a fungal elicitor secreted by Phytophthora cryptogea, a member of a novel class of plant necrotic proteins

https://doi.org/10.1016/S0969-2126(96)00150-5Get rights and content
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Abstract

Background: Elicitins form a novel class of plant necrotic proteins which are secreted by Phytophthora and Pythium fungi, parasites of many economically important crops. These proteins induce leaf necrosis in infected plants and elicit an incompatible hypersensitive-like reaction, leading to the development of a systemic acquired resistance against a range of fungal and bacterial plant pathogens. No crystal structures of this class of protein are available. The crystal structure determination of β-cryptogein (CRY), secreted by Phytophthora cryptogea, was undertaken to identify structural features important for the necrotic activity of elicitins.

Results: The structure of CRY was determined using the multiwavelength anomalous diffraction technique and refined to 2.2 å resolution. The overall structure has a novel fold consisting of six α helices and a beak-like motif, whose sequence is highly conserved within the family, composed of an antiparallel two-stranded β sheet and an Ω loop. This motif is assumed to be a major recognition site for a putative receptor and/or ligand. Two other distinct binding sites seem to be correlated to the level of necrotic activity of elicitins.

Conclusions: The determination of the crystal structure of a member of the elicitin family may make it possible to separate the activity that causes leaf necrosis from that inducing systemic acquired resistance to pathogens, making it feasible to engineer a non-toxic elicitin that only elicits plant defences. Such studies should aid the development of non-toxic agricultural pest control.

Keywords

elicitin
multiwavelength anomalous diffraction (MAD)
plant pathogen
toxin
X-ray crystallography

Cited by (0)

G Boissy, JC Huet, JC Pernollet and S Brunie, Unité de Recherche Biochimie & Structure des Protéines, INRA, 78352 Jouy-en-Josas, France.

E de La Fortelle, MRC-LMB, Hills Road, Cambridge CB2 2QH, UK.

R Kahn, IBS, 41 Av. des Martyrs, 38027 Grenoble, Cedex 1, France.

G Bricogne, MRC-LMB, Hills Road, Cambridge CB2 2QH, UK and L.U.R.E, Bât. 209d, 91405 Orsay Cedex, France.

E-mail address for S Brunie (corresponding author): [email protected].