Purification, Characterization, and Amino Acid Sequence of Cerato-platanin, a New Phytotoxic Protein from Ceratocystis fimbriata f. sp. platani

Abstract

A new phytotoxic protein (cerato-platanin) of about 12.4 kDa has been identified in culture filtrates of the Ascomycete Ceratocystis fimbriata f. sp. platani, the causal agent of canker stain disease. The toxicity of the pure protein was bioassayed by detecting the inducing necrosis in tobacco leaves. The pure protein also elicited host synthesis of fluorescent substances in tobacco and plane (Platanus acerifolia) leaves. We purified the protein from culture medium to homogeneity. Its complete amino acid sequence was determined; this protein consists of 120 amino acid residues, contains 4 cysteines (S-S-bridged), and has a high percentage of hydrophobic residues. The molecular weight calculated from the amino acid sequence agrees with that determined by mass spectrometry, suggesting that no post-transnational modification occurs. Searches performed by the BLAST program in data banks (Swiss-Prot, EBI, and GenBank) revealed that this protein is highly homologous with two proteins produced by other Ascomycete fungi. One, produced during infection of wheat leaves, is codified by the snodprot1 gene of Phaeosphaeria nodorum (the causal agent of glume blotch of wheat), whereas the other is the rAsp f13 allergen from Aspergillus fumigatus. Furthermore, the N terminus of cerato-platanin is homologous with that of cerato-ulmin, a phytotoxic protein belonging to the hydrophobin family and produced by Ophiostoma (Ceratocystis) ulmi, a fungus responsible for Dutch elm disease.The European plane tree (Platanus acerifolia) is an ornamental plant species of the urban environment. A great number of plane trees in the parks and towns of southern Europe have been destroyed by Ceratocystis fimbriata (Ell. and Halst.) Davidson f. sp. platani Walter, the Ascomycete responsible for canker stain disease (1). This disease is characterized by foliar wilting and spreading lesions that involve phloem, cambium, and extensive regions of sapwood (2, 3). The pathogen spreads from tree to tree by means of root grafts of closely spaced plants and, more frequently, through wounds caused by pruning (4).The American species Platanus occidentalis has been shown to contain a source of resistance to C. fimbriata f. sp. platani that could prove of great interest in the genetic improvement of the European plane (5). Known post-infection host defense mechanisms involve physical factors such as the occlusion of the xylematic vessels and the compartmentalization of infected tissue areas as well as the production of flavans, umbelliferone, and scopoletine phytoalexins (6 -9). Unfortunately, only resistant P. occidentalis clones, not yet acclimatized to Europe, localized the disease (7,8). Recent papers (10, 11) have shown that C. fimbriata f. sp. platani displays an array of phytotoxic metabolites possibly involved in determining some of the symptoms of canker stain.In the present paper we report on the purification procedure, the amino acid sequence, and the characterization of the biological activity of a new protein (named cerato-platanin) from the cul...

Phytotoxic Protein PcF, Purification, Characterization, and cDNA Sequencing of a Novel Hydroxyproline-containing Factor Secreted by the Strawberry Pathogen Phytophthora cactorum

“…2, the purified PcF (80 g) induced the formation of a marked necrotic area within 24 h after leaf infiltration. Such a level of activity is comparable with that of previously reported phytotoxic fungal proteins toward their hosts (33,34). Our findings indicate an involvement of the PcF protein in this P. cactorum-Fragaria interaction as an host-specific factor.…”

Cerato-platanin shows expansin-like activity on cellulosic materials

“…The three-dimensional structure of this protein has been defined: CP has a double ψβ-barrel fold similar to that occurring in endoglucanases, in the plant defence protein barwin and in domain I of expansins (de Oliveira et al 2011). However, CP does not show hydrolytic activity and is known to the scientific community for its eliciting activity on plants (Fontana et al 2008;de Oliveira et al 2011;Pazzagli et al 1999;Scala et al 2004).…”

“…Cerato-platanin (CP) is a small protein (12.4 kDa) produced by the phytopathogenic fungus Ceratocystis platani, the causal agent of canker in plane trees (Pazzagli et al 1999). CP is a component of the cell wall of C. platani, but is also released during growth (Bernardi et al 2011;Boddi et al 2004;Scala et al 2004).…”

Finding of a novel fungal immunomodulatory protein coding sequence in Ganoderma australe

“…Both G. australe c13717 and Tai. camphoratus proteins consisted of two α helices and seven b sheets, with the exception of a short additional b sheet in c13717, which was considered non-significant, due to a low prediction no acid residues, with four cysteine residues that form two disulfide bridges contributing to protein structure (Pazzagli et al, 1999). Indeed, the immunomodulatory protein predicted from G. australe is not, in a strict sense, an immunomodulatory protein belonging to the FIP family, like other proteins previously reported for Ganoderma.…”