New Enzymatic Virulence Factors In Phytophthora Infestans

马铃薯晚疫病菌中新的酶促毒力因子

• 批准号: BB/V000365/1
• 负责人: Katherine Denby
• 金额: $ 66.17万
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FV000365%2F1
• 关键词: New; Enzymatic; Virulence; Factors; Phytophthora

Oomycetes are fungal-like eukaryotic organisms evolutionarily related to diatoms and brown algae, and cause some of the most devastating plant and animal diseases in agriculture and aquaculture. The Phytophthora genus contains over 140 species, including the late blight pathogen Phytophthora infestans, which caused the Irish potato famine that led to death-by-starvation of over one million people in the 19th century. P. infestans infects both potato and tomato crops and is the most damaging oomycete pathogen in agriculture, causing economic losses in excess of $6 billion annually. Plant pathogens need to penetrate the plant cell wall in order to infect their host, and major aspects of the molecular struggle between the host and pathogen occur in the cell wall. Pathogens, such as P. infestans, secrete a range of cell wall degrading enzymes to facilitate host penetration. Many of these pathogen enzymes (such as polygalacturonase and pectin methylesterase) target the pectin components of plant cell walls. Pectins provide the glue that binds plant cells to one another, and degrading pectin allows the pathogen to grow through the middle lamella between plant cells. In response, plants have evolved a range of counter measures, including inhibitors of pathogen enzymes. These anti-pathogen responses are induced in plants following the detection of small molecules derived from breakdown of the host cell wall (such as pectic oligogalacturonides) by pathogen enzymes.We recently discovered a new class of lytic polysaccharide monooxygenase (LPMO) enzymes in oomycetes, which are notably abundant in plant pathogenic species, such as P. infestans. Three LPMO genes in P. infestans are highly expressed very early during plant infection, ands blocking the action of the most abundantly expressed of these impedes the pathogen's ability to infect plant tissues, suggesting it is important for host penetration. Previously characterised classes of LPMOs are oxidative enzymes able to digest the most recalcitrant forms of polysaccharides such as crystalline cellulose or chitin. We have shown that the most expressed P. infestans LPMO oxidatively attacks polygalacturonan, the main pectic polymer in plants. This is the first time LPMOs have been shown to attack pectins, indicating this enzyme has evolved specifically to facilitate host penetration, perhaps helping the pathogen to evade the polygalacturonase- and pectin methyl esterase-inhibiting proteins produced by the host. Previously published work has shown that oxidised oligogalacturonides do not induce pathogen responses in plants, suggesting that LPMO attack may help the pathogen to slip under the host's radar. Gene expression studies indicate a range of other, uncharacterised, secreted enzymes are produced early in infection. We propose to study the roles of these proteins during infection and assess their importance in the ability of the pathogen to infect plants.To achieve our aims we will generate an inventory of proteins found in the host cell wall during early pathogen infection using highly sensitive proteomic approaches. This will provide a comprehensive view of pathogen and host proteins expressed during infection. We will select a subset of these proteins for further study including the LPMO family. The selection of targets for study will be based on their novelty and their importance in pathogenesis based on gene silencing studies. We will study the biochemical activity of recombinant versions of target proteins, characterise their 3-dimensional structure, and study their specific localisation in the cell wall during infection. The results of our studies will provide new understanding of enzymes and proteins produced by pathogens during infection and by host plants in response to this. The pathogen genes that we show to be important for infection (such as the LPMOs) will provide new molecular targets for targeted crop protection strategies.

卵菌是类真菌真核生物，在进化上与硅藻和褐藻相关，并导致农业和水产养殖中一些最具破坏性的动植物疾病。疫霉属包含 140 多个物种，其中包括晚疫病病原体致病疫霉 (Phytophthora infestans)，它引起了爱尔兰马铃薯饥荒，导致 19 世纪超过一百万人饿死。 P. infestans 感染马铃薯和番茄作物，是农业中最具破坏性的卵菌病原体，每年造成超过 60 亿美元的经济损失。植物病原体需要穿透植物细胞壁才能感染宿主，宿主和病原体之间分子斗争的主要方面发生在细胞壁中。致病疫霉等病原体会分泌一系列细胞壁降解酶以促进宿主渗透。许多这些病原体酶（例如多聚半乳糖醛酸酶和果胶甲酯酶）以植物细胞壁的果胶成分为目标。果胶提供了将植物细胞彼此粘合在一起的胶水，降解果胶使病原体能够通过植物细胞之间的中间层生长。作为回应，植物进化出了一系列应对措施，包括病原体酶抑制剂。这些抗病原体反应是在检测到由病原体酶分解宿主细胞壁（例如果胶低聚半乳糖醛酸）衍生的小分子后在植物中诱导的。我们最近在卵菌中发现了一类新的裂解多糖单加氧酶（LPMO）酶，它们在植物病原菌中尤其丰富，例如致病疫霉。 P. infestans 中的三个 LPMO 基因在植物感染过程的早期就高度表达，并且阻断其中最丰富表达的基因的作用会阻碍病原体感染植物组织的能力，这表明它对于宿主渗透很重要。先前表征的 LPMO 类别是氧化酶，能够消化最顽固形式的多糖，例如结晶纤维素或甲壳质。我们已经表明，表达最多的致病疫霉 LPMO 会氧化攻击植物中主要果胶聚合物聚半乳糖醛酸。这是首次证明 LPMO 可以攻击果胶，表明这种酶的进化是为了促进宿主渗透，可能有助于病原体逃避宿主产生的多聚半乳糖醛酸酶和果胶甲酯酶抑制蛋白。先前发表的研究表明，氧化低聚半乳糖醛酸不会诱导植物中的病原体反应，这表明 LPMO 攻击可能有助于病原体躲过宿主的雷达。基因表达研究表明，在感染早期会产生一系列其他未表征的分泌酶。我们建议研究这些蛋白质在感染过程中的作用，并评估它们在病原体感染植物的能力中的重要性。为了实现我们的目标，我们将使用高度敏感的蛋白质组学来生成早期病原体感染期间宿主细胞壁中发现的蛋白质清单接近。这将提供感染期间表达的病原体和宿主蛋白的全面视图。我们将选择这些蛋白质的子集进行进一步研究，包括 LPMO 家族。研究目标的选择将基于其新颖性及其在基于基因沉默研究的发病机制中的重要性。我们将研究目标蛋白重组版本的生化活性，表征其 3 维结构，并研究它们在感染过程中在细胞壁中的特定定位。我们的研究结果将为病原体在感染过程中产生的酶和蛋白质以及宿主植物对此做出的反应提供新的认识。我们证明对感染很重要的病原体基因（例如 LPMO）将为有针对性的作物保护策略提供新的分子靶点。

项目成果

Lytic Polysaccharide Monooxygenases as Chitin-Specific Virulence Factors in Crayfish Plague.

• DOI: 10.3390/biom11081180
• 发表时间: 2021-08-09
• 期刊: Biomolecules
• 影响因子: 5.5
• 作者: Sabbadin F;Henrissat B;Bruce NC;McQueen-Mason SJ
• 通讯作者: McQueen-Mason SJ

Characterisation of the enzyme transport path between shipworms and their bacterial symbionts.

• DOI: 10.1186/s12915-021-01162-6
• 发表时间: 2021-11-01
• 期刊: BMC biology
• 影响因子: 5.4
• 作者: Pesante G;Sabbadin F;Elias L;Steele-King C;Shipway JR;Dowle AA;Li Y;Busse-Wicher M;Dupree P;Besser K;Cragg SM;Bruce NC;McQueen-Mason SJ
• 通讯作者: McQueen-Mason SJ