Comparative study of Arabidopsis PBS1 and a wheat PBS1 homolog helps understand the mechanism of PBS1 functioning in innate immunity

• Published in: Scientific reports Vol. 7; no. 1; pp. 5487 - 12
• Main Authors: Sun, Jianhang, Huang, Guozhong, Fan, Fenggui, Wang, Shuangfeng, Zhang, Yingying, Han, Yufang, Zou, Yanmin, Lu, Dongping
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.07.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 13; 14; 14/19; 38; 38/109; 38/39; 38/90; 45; 45/22; 45/23; 45/29; 45/44; 45/77; 45/90; 631/449/2169; 631/449/2675; 82; 82/29; 82/80; 82/83; 96; Amino Acid Motifs; Amino Acid Sequence; Amino acids; Arabidopsis; Arabidopsis - immunology; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Bacterial Proteins - metabolism; Cell Membrane - drug effects; Cell Membrane - metabolism; Flagellin; Flagellin - pharmacology; Flowers & plants; Genomes; Humanities and Social Sciences; Hypersensitive response; Immunity, Innate - drug effects; Innate immunity; Kinases; Microorganisms; multidisciplinary; Pathogens; Peptides; Peptides - pharmacology; Phosphorylation; Phosphorylation - drug effects; Phylogeny; Plant Immunity - drug effects; Plant Proteins - chemistry; Plant Proteins - metabolism; Protein Binding - drug effects; Protein Domains; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - metabolism; Proteins; Protoplasts - drug effects; Protoplasts - metabolism; Science; Science (multidisciplinary); Sequence Homology, Amino Acid; Triticum; Triticum - immunology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-05904-x

Arabidopsis AVRPPHB SUSCEPTIBLE1 (PBS1) serves as a “decoy” in activating RESISTANCE TO PSEUDOMONAS SYRINGAE5 (RPS5) upon cleavage by Pseudomonas phaseolicola B (AvrPphB), a Pseudomonas syringae effector. The SEMPH motif in PBS1 was thought to allow it to be distinguished by RPS5 from the closely related Arabidopsis kinases. However, the underlying mechanism is not fully understood. Here, we isolated and characterized a wheat PBS1 homolog, TaPBS1. Although this plasma membrane-localized kinase could be cleaved by AvrPphB and could associate with RPS5, it failed to trigger RPS5-mediated hypersensitive response (HR) in a transient assay. TaPBS1 harbors a STRPH motif. The association of RPS5 with TaPBS1 was weaker than with PBS1. Change of the STRPH motif to the SEMPH motif allowed TaPBS1 to trigger HR. However, the SEMPH motif is not required for association of PBS1 with RPS5. The difference between “SEMPH” and “STRPH” points to the importance of “EM” in PBS1. Furthermore we found that a negatively charged amino acid at the position of “E” in the SEMPH motif was required for recognition of PBS1 by RPS5. Additionally, both PBS1 and TaPBS1 undergo the flagellin-induced phosphorylation. Therefore, our work will help understand the mechanism of PBS1 functioning in plant innate immunity.