Multiple variants of the blast fungus effector AVR-Pik bind the HMA domain of the rice protein OsHIPP19 with high affinity
Multiple variants of the blast fungus effector AVR-Pik bind the HMA domain of the rice protein OsHIPP19 with high affinity
复制标题
DOI：
10.1101/2020.12.01.403451
复制
发表时间：
2020-12
期刊：
影响因子：
--
通讯作者：
J. Maidment;M. Franceschetti;A. Maqbool;H. Saitoh;C. Jantasuriyarat;S. Kamoun;R. Terauchi;M. Banfield
中科院分区：
文献类型：
--
作者：
J. Maidment;M. Franceschetti;A. Maqbool;H. Saitoh;C. Jantasuriyarat;S. Kamoun;R. Terauchi;M. Banfield
微生物植物病原体分泌操纵宿主以促进感染的效应蛋白。效应子可以被植物细胞内的核苷酸结合富亮氨酸重复序列（NLR）受体识别，启动免疫应答。来自稻瘟病菌的AVR-Pik效应子被一对水稻NLR受体Pik-1和Pik-2识别。Pik-1含有一个非典型的整合重金属相关（HMA）结构域，其直接结合AVR-Pik以激活植物防御。非典型整合结构域广泛存在于植物NLR中，并被认为类似于识别的效应子的宿主靶标。AVR-Pik与特定的水稻HMA结构域蛋白相互作用，即重金属相关异戊二烯化植物蛋白（HIPPs）和重金属相关植物蛋白（HPPs）。在这里，我们定义了AVR-Pik和OsHIPP 19之间相互作用的生化和结构基础，并比较了与Pik-1的HMA结构域的相互作用。使用分析凝胶过滤和表面等离子体共振，我们表明，多种AVR-Pik变体，包括不与任何特征化的Pik-1等位基因相互作用的隐形变体AVR-PikC和AVR-PikF，以纳摩尔亲和力结合OsHIPP 19。与AVR-PikF复合的OsHIPP 19的晶体结构揭示了界面处的差异，这些差异支持OsHIPP 19-HMA与比由Pik-1的整合的HMA结构域实现的更广泛的AVR-Pik变体的高亲和力结合。我们的研究结果提供了一个基础，工程化的HMA结构域的Pik-1，以扩大结合到目前未识别的AVR-Pik变异体和扩大抗病性水稻不同的病原体菌株。
Microbial plant pathogens secrete effector proteins which manipulate the host to promote infection. Effectors can be recognised by plant intracellular nucleotide-binding leucine-rich repeat (NLR) receptors, initiating an immune response. The AVR-Pik effector from the rice blast fungus Magnaporthe oryzae is recognised by a pair of rice NLR receptors, Pik-1 and Pik-2. Pik-1 contains a non-canonical integrated heavy metal-associated (HMA) domain, which directly binds AVR-Pik to activate plant defences. Non-canonical integrated domains are widespread in plant NLRs and are thought to resemble the host target of the recognised effector. AVR-Pik interacts with specific rice HMA domain-containing proteins, namely heavy metal-associated isoprenylated plant proteins (HIPPs) and heavy metal-associated plant proteins (HPPs). Here, we define the biochemical and structural basis of the interaction between AVR-Pik and OsHIPP19, and compare the interaction with the HMA domain of Pik-1. Using analytical gel filtration and surface plasmon resonance, we show that multiple AVR-Pik variants, including the stealthy variants AVR-PikC and AVR-PikF which do not interact with any characterised Pik-1 alleles, bind to OsHIPP19 with nanomolar affinity. The crystal structure of OsHIPP19 in complex with AVR-PikF reveals differences at the interface that underpin high-affinity binding of OsHIPP19-HMA to a wider set of AVR-Pik variants than achieved by the integrated HMA domain of Pik-1. Our results provide a foundation for engineering the HMA domain of Pik-1 to extend binding to currently unrecognised AVR-Pik variants and expand disease resistance in rice to divergent pathogen strains.