| Structural highlights
Function
XEG1_PHYSP Glycoside hydrolase that exhibits xyloglucanase activity (PubMed:26163574). Acts as an important virulence factor during P.sojae infection but also acts as a pathogen-associated molecular pattern (PAMP) in soybean and solanaceous species, where it can trigger defense responses including cell death. XEG1-induced cell death can be suppressed by P.sojae RxLR effectors. The PAMP activity is independent of its xyloglucanase activity (PubMed:26163574). XEG1 induces plant defense responses in a RLP kinase Serk3/Bak1-dependent manner in Nicotiana benthamiana. Moreover, the perception of XEG1 occurs independently of the perception of ethylene-inducing xylanase Eix2 in Tomato (PubMed:26163574). With truncated paralog XLP1, is required to elevate apoplastic sugar during P.sojae infection (PubMed:28082413).[1] [2]
Publication Abstract from PubMed
Plants rely on cell-surface-localized pattern recognition receptors to detect pathogen- or host-derived danger signals and trigger an immune response(1-6). Receptor-like proteins (RLPs) with a leucine-rich repeat (LRR) ectodomain constitute a subgroup of pattern recognition receptors and play a critical role in plant immunity(1-3). Mechanisms underlying ligand recognition and activation of LRR-RLPs remain elusive. Here we report a crystal structure of the LRR-RLP RXEG1 from Nicotiana benthamiana that recognizes XEG1 xyloglucanase from the pathogen Phytophthora sojae. The structure reveals that specific XEG1 recognition is predominantly mediated by an amino-terminal and a carboxy-terminal loop-out region (RXEG1(ID)) of RXEG1. The two loops bind to the active-site groove of XEG1, inhibiting its enzymatic activity and suppressing Phytophthora infection of N. benthamiana. Binding of XEG1 promotes association of RXEG1(LRR) with the LRR-type co-receptor BAK1 through RXEG1(ID) and the last four conserved LRRs to trigger RXEG1-mediated immune responses. Comparison of the structures of apo-RXEG1(LRR), XEG1-RXEG1(LRR) and XEG1-BAK1-RXEG1(LRR) shows that binding of XEG1 induces conformational changes in the N-terminal region of RXEG1(ID) and enhances structural flexibility of the BAK1-associating regions of RXEG1(LRR). These changes allow fold switching of RXEG1(ID) for recruitment of BAK1(LRR). Our data reveal a conserved mechanism of ligand-induced heterodimerization of an LRR-RLP with BAK1 and suggest a dual function for the LRR-RLP in plant immunity.
Plant receptor-like protein activation by a microbial glycoside hydrolase.,Sun Y, Wang Y, Zhang X, Chen Z, Xia Y, Wang L, Sun Y, Zhang M, Xiao Y, Han Z, Wang Y, Chai J Nature. 2022 Oct;610(7931):335-342. doi: 10.1038/s41586-022-05214-x. Epub 2022 , Sep 21. PMID:36131021[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ma Z, Song T, Zhu L, Ye W, Wang Y, Shao Y, Dong S, Zhang Z, Dou D, Zheng X, Tyler BM, Wang Y. A Phytophthora sojae Glycoside Hydrolase 12 Protein Is a Major Virulence Factor during Soybean Infection and Is Recognized as a PAMP. Plant Cell. 2015 Jul;27(7):2057-72. PMID:26163574 doi:10.1105/tpc.15.00390
- ↑ Ma Z, Zhu L, Song T, Wang Y, Zhang Q, Xia Y, Qiu M, Lin Y, Li H, Kong L, Fang Y, Ye W, Wang Y, Dong S, Zheng X, Tyler BM, Wang Y. A paralogous decoy protects Phytophthora sojae apoplastic effector PsXEG1 from a host inhibitor. Science. 2017 Feb 17;355(6326):710-714. PMID:28082413 doi:10.1126/science.aai7919
- ↑ Sun Y, Wang Y, Zhang X, Chen Z, Xia Y, Wang L, Sun Y, Zhang M, Xiao Y, Han Z, Wang Y, Chai J. Plant receptor-like protein activation by a microbial glycoside hydrolase. Nature. 2022 Oct;610(7931):335-342. doi: 10.1038/s41586-022-05214-x. Epub 2022, Sep 21. PMID:36131021 doi:http://dx.doi.org/10.1038/s41586-022-05214-x
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