Breit-McNally Clare, Laflamme Bradley, Singh Racquel A, Desveaux Darrell, Guttman David S
Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.
Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, ON, Canada.
Front Plant Sci. 2022 Sep 23;13:981684. doi: 10.3389/fpls.2022.981684. eCollection 2022.
A key facet of innate immunity in plants entails the recognition of pathogen "effector" virulence proteins by host Nucleotide-Binding Leucine-Rich Repeat Receptors (NLRs). Among characterized NLRs, the broadly conserved ZAR1 NLR is particularly remarkable due to its capacity to recognize at least six distinct families of effectors from at least two bacterial genera. This expanded recognition spectrum is conferred through interactions between ZAR1 and a dynamic network of two families of Receptor-Like Cytoplasmic Kinases (RLCKs): ZED1-Related Kinases (ZRKs) and PBS1-Like Kinases (PBLs). In this review, we survey the history of functional studies on ZAR1, with an emphasis on how the ZAR1-RLCK network functions to trap diverse effectors. We discuss 1) the dynamics of the ZAR1-associated RLCK network; 2) the specificity between ZRKs and PBLs; and 3) the specificity between effectors and the RLCK network. We posit that the shared protein fold of kinases and the switch-like properties of their interactions make them ideal effector sensors, enabling ZAR1 to act as a broad spectrum guardian of host kinases.
植物先天免疫的一个关键方面是宿主核苷酸结合富含亮氨酸重复受体（NLRs）对病原体“效应子”毒力蛋白的识别。在已鉴定的NLRs中，广泛保守的ZAR1 NLR特别引人注目，因为它能够识别至少两个细菌属的至少六个不同的效应子家族。这种扩展的识别谱是通过ZAR1与两个类受体细胞质激酶（RLCKs）家族的动态网络之间的相互作用赋予的：ZED1相关激酶（ZRKs）和PBS1样激酶（PBLs）。在这篇综述中，我们概述了ZAR1功能研究的历史，重点是ZAR1-RLCK网络如何捕获不同的效应子。我们讨论了：1）与ZAR1相关的RLCK网络的动态变化；2）ZRKs和PBLs之间的特异性；3）效应子与RLCK网络之间的特异性。我们认为，激酶的共享蛋白结构域及其相互作用的开关样特性使其成为理想的效应子传感器，使ZAR1能够作为宿主激酶的广谱守护者发挥作用。
