RESUMO
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 At HEL. 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.
Assuntos
Proteínas de Arabidopsis/análise , Proteínas de Arabidopsis/metabolismo , Arabidopsis/química , Arabidopsis/metabolismo , Proteínas de Membrana/análise , Proteínas de Membrana/metabolismo , Antifúngicos/análise , Antifúngicos/metabolismo , Peptídeos Catiônicos Antimicrobianos/análise , Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Catiônicos Antimicrobianos/metabolismo , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Quitinases/análise , Quitinases/genética , Quitinases/metabolismo , Proteínas de Membrana/genética , Modelos Moleculares , Lectinas de Plantas/análise , Lectinas de Plantas/genética , Lectinas de Plantas/metabolismo , Processamento de Proteína Pós-Traducional , Estrutura Terciária de Proteína , Proteínas Recombinantes/análise , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Ribonucleases/análise , Ribonucleases/genética , Ribonucleases/metabolismoRESUMO
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.
Assuntos
Proteínas de Arabidopsis/química , Lectinas/metabolismo , Proteínas de Plantas/química , Sequência de Aminoácidos , Antifúngicos/química , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/farmacologia , Sítios de Ligação , Quitina/química , Quitina/metabolismo , Carpóforos/fisiologia , Fusarium/efeitos dos fármacos , Fusarium/crescimento & desenvolvimento , Lectinas/química , Modelos Moleculares , Dados de Sequência Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/farmacologia , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Ribonucleases/química , Ribonucleases/genética , Ribonucleases/metabolismo , Homologia de Sequência de Aminoácidos , Triticum/genéticaRESUMO
In summer 2016 a severe infestation of the alien ambrosia beetle Xylosandrus compactus was recorded from the Mediterranean maquis in the Circeo National Park in Central Italy. Trees and shrubs were infested and displayed wilting and necrosis of terminal branches caused by the combined impact of the insect and associated pathogenic fungi. A preliminary screening carried out on captured adults resulted in the isolation of a discrete number of fungal taxa with different life strategies, ranging from true mutualist (e.g. Ambrosiella xylebori) to plant pathogens (Fusarium spp.). In the present study, high-throughput sequencing was applied to determine the total diversity and functionality of the fungal community associated with X. compactus adults collected in the galleries of three Mediterranean woody hosts, Quercus ilex, Laurus nobilis, and Ceratonia siliqua. The effect of season and host in determining the composition of the associated fungal community was investigated. A total of 206 OTUs composed the fungal community associated with X. compactus. Eighteen OTUs were shared among the three hosts, including A. xylebori and members of the Fusarium solani complex. All but two were previously associated with beetles. Sixty-nine out of 206 OTUs were resolved to species level, identifying 60 different fungal species, 22 of which already reported in the literature as associated with beetles or other insects. Functional guild assigned most of the fungal species to saprotrophs and plant pathogens. Effects of seasonality and host on fungal community assemblage were highlighted suggesting the acquisition by the insect of new fungal taxa during the invasion process. The consequences of enriched fungal community on the risk of the insurgence of novel threatful insect-fungus association are discussed considering direct and indirect effects on the invaded habitat.