Offor Benedict C, Mhlongo Msizi I, Dubery Ian A, Piater Lizelle A
Department of Biochemistry, University of Johannesburg, Auckland Park, Johannesburg 2006, South Africa.
Membranes (Basel). 2022 Jun 10;12(6):606. doi: 10.3390/membranes12060606.
Plants recognise bacterial microbe-associated molecular patterns (MAMPs) from the environment via plasma membrane (PM)-localised pattern recognition receptor(s) (PRRs). Lipopolysaccharides (LPSs) are known as MAMPs from gram-negative bacteria that are most likely recognised by PRRs and trigger defence responses in plants. The Arabidopsis PRR(s) and/or co-receptor(s) complex for LPS and the associated defence signalling remains elusive. As such, proteomic identification of LPS receptors and/or co-receptor complexes will help to elucidate the molecular mechanisms that underly LPS perception and defence signalling in plants. The Arabidopsis LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI)-related-2 (LBR2) have been shown to recognise LPS and trigger defence responses while brassinosteroid insensitive 1 (BRI1)-associated receptor kinase 1 (BAK1) acts as a co-receptor for several PRRs. In this study, Arabidopsis wild type (WT) and T-DNA knock out mutants ( and ) were treated with LPS chemotypes from pv. DC3000 () and pv. 8004 () over a 24 h period. The PM-associated protein fractions were separated by liquid chromatography and analysed by tandem mass spectrometry (LC-MS/MS) followed by data analysis using Byonic software. Using Gene Ontology (GO) for molecular function and biological processes, significant LPS-responsive proteins were grouped according to defence and stress response, perception and signalling, membrane transport and trafficking, metabolic processes and others. Venn diagrams demarcated the MAMP-responsive proteins that were common and distinct to the WT and mutant lines following treatment with the two LPS chemotypes, suggesting contributions from differential LPS sub-structural moieties and involvement of LBR2 and BAK1 in the LPS-induced MAMP-triggered immunity (MTI). Moreover, the identification of RLKs and RLPs that participate in other bacterial and fungal MAMP signalling proposes the involvement of more than one receptor and/or co-receptor for LPS perception as well as signalling in Arabidopsis defence responses.
植物通过位于质膜（PM）的模式识别受体（PRR）识别来自环境的细菌微生物相关分子模式（MAMP）。脂多糖（LPS）是革兰氏阴性细菌的MAMP，很可能被PRR识别并触发植物的防御反应。拟南芥中识别LPS的PRR和/或共受体复合物以及相关的防御信号传导仍不清楚。因此，对LPS受体和/或共受体复合物进行蛋白质组学鉴定将有助于阐明植物中LPS感知和防御信号传导的分子机制。拟南芥LPS结合蛋白（LBP）和杀菌/通透性增加蛋白（BPI）相关蛋白2（LBR2）已被证明可识别LPS并触发防御反应，而油菜素内酯不敏感1（BRI1）相关受体激酶1（BAK1）作为几种PRR的共受体。在本研究中，拟南芥野生型（WT）和T-DNA敲除突变体（ 和 ）在24小时内用来自丁香假单胞菌番茄致病变种（Pst）DC3000（ ）和丁香假单胞菌辣椒致病变种8004（ ）的LPS化学型处理。通过液相色谱分离与质膜相关的蛋白质组分，并通过串联质谱（LC-MS/MS）进行分析，随后使用Byonic软件进行数据分析。利用基因本体论（GO）对分子功能和生物学过程进行分析，根据防御和应激反应、感知和信号传导、膜运输和 trafficking、代谢过程等对显著的LPS反应蛋白进行分组。维恩图划分了用两种LPS化学型处理后野生型和突变体系中常见和不同的MAMP反应蛋白，表明不同的LPS亚结构部分以及LBR2和BAK1参与了LPS诱导的MAMP触发免疫（MTI）。此外，参与其他细菌和真菌MAMP信号传导的受体样激酶（RLK）和受体样蛋白（RLP）的鉴定表明，在拟南芥防御反应中，LPS感知以及信号传导涉及不止一种受体和/或共受体。
