https://www.cell.com/molecular-plant/pdf/S1674-2052(14)60932-1.pdf

Growth-defense tradeoffs in plants: a balancing act to optimize fitness.

Plants depend on cell-autonomous innate immune mechanisms for protection against infection and these pathways are activated in response to pattern recognition receptor (PRR) engagement. However, as is the case in mammals, PRR signalling in plants must be tightly controlled to avoid pathological outcomes; this Review focuses on the mechanisms that regulate plant PRR signalling.

Regulation of pattern recognition receptor signalling in plants.

https://www.cell.com/trends/immunology/pdf/S1471-4906(14)00094-5.pdf

Plant pattern-recognition receptors.

Plant PRRs and the Activation of Innate Immune Signaling

Direct regulation of the NADPH oxidase RBOHD by the PRR-associated kinase BIK1 during plant immunity.

Flagellin perception in Arabidopsis is through recognition of its highly conserved N-terminal epitope (flg22) by flagellin-sensitive 2 (FLS2). Flg22 binding induces FLS2 heteromerization with BRASSINOSTEROID INSENSITIVE 1-associated kinase 1 (BAK1) and their reciprocal activation followed by plant immunity. Here, we report the crystal structure of FLS2 and BAK1 ectodomains complexed with flg22 at 3.06 angstroms. A conserved and a nonconserved site from the inner surface of the FLS2 solenoid recognize the C- and N-terminal segment of flg22, respectively, without oligomerization or conformational changes in the FLS2 ectodomain. Besides directly interacting with FLS2, BAK1 acts as a co-receptor by recognizing the C terminus of the FLS2-bound flg22. Our data reveal the molecular mechanisms underlying FLS2-BAK1 complex recognition of flg22 and provide insight into the immune receptor complex activation.

https://science.sciencemag.org/content/sci/342/6158/624.full.pdf

Structural basis for flg22-induced activation of the Arabidopsis FLS2-BAK1 immune complex.

/pdf/structure-reveals-that-bak1-as-a-co-receptor-recognizes-the-54dqwpg79v.pdf

Structure reveals that BAK1 as a co-receptor recognizes the BRI1-bound brassinolide

The endogenous peptides AtPep1-8 in Arabidopsis mature from the conserved C-terminal portions of their precursor proteins PROPEP1-8, respectively The two homologous leucine-rich repeat-receptor kinases (LRR-RKs) PEPR1 and PEPR2 act as receptors of AtPeps AtPep binding leads to stable association of PEPR1,2 with the shared receptor LRR-RK BAK1, eliciting immune responses similar to those induced by pathogens Here we report a crystal structure of the extracellular LRR domain of PEPR1 (PEPR1LRR) in complex with AtPep1 The structure reveals that AtPep1 adopts a fully extended conformation and binds to the inner surface of the superhelical PEPR1LRR Biochemical assays showed that AtPep1 is capable of inducing PEPR1LRR-BAK1LRR heterodimerization The conserved C-terminal portion of AtPep1 dominates AtPep1 binding to PEPR1LRR, with the last amino acid of AtPep1 Asn23 forming extensive interactions with PEPR1LRR Deletion of the last residue of AtPep1 significantly compromised AtPep1 interaction with PEPR1LRR Together, our data reveal a conserved structural mechanism of AtPep1 recognition by PEPR1, providing significant insight into prediction of recognition of other peptides by their cognate LRR-RKs

/pdf/structural-basis-for-recognition-of-an-endogenous-peptide-by-58q2dxd9k9.pdf

Structural basis for recognition of an endogenous peptide by the plant receptor kinase PEPR1

Nearly all eukaryotic messenger RNA precursors must undergo cleavage and polyadenylation at their 3′-end for maturation. A crucial step in this process is the recognition of the AAUAAA polyadenylation signal (PAS), and the molecular mechanism of this recognition has been a long-standing problem. Here, we report the cryo-electron microscopy structure of a quaternary complex of human CPSF-160, WDR33, CPSF-30, and an AAUAAA RNA at 3.4-A resolution. Strikingly, the AAUAAA PAS assumes an unusual conformation that allows this short motif to be bound directly by both CPSF-30 and WDR33. The A1 and A2 bases are recognized specifically by zinc finger 2 (ZF2) of CPSF-30 and the A4 and A5 bases by ZF3. Interestingly, the U3 and A6 bases form an intramolecular Hoogsteen base pair and directly contact WDR33. CPSF-160 functions as an essential scaffold and preorganizes CPSF-30 and WDR33 for high-affinity binding to AAUAAA. Our findings provide an elegant molecular explanation for how PAS sequences are recognized for mRNA 3′-end formation.

https://www.pnas.org/content/pnas/115/7/E1419.full.pdf

Yadong Sun

Papers

Structural basis for flg22-induced activation of the Arabidopsis FLS2-BAK1 immune complex.

Structure reveals that BAK1 as a co-receptor recognizes the BRI1-bound brassinolide

Structural basis for recognition of an endogenous peptide by the plant receptor kinase PEPR1

Molecular basis for the recognition of the human AAUAAA polyadenylation signal.

Structural insight into the activation of plant receptor kinases.