1. Biosynthesis and secretion of the microbial sulfated peptide RaxX and binding to the rice XA21 immune receptor
- Author
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Valley Stewart, Kanya C. Long, Clifford Adamchak, Rory N Pruitt, Pamela C. Ronald, Dee Dee Luu, Katarzyna Parys, Leanne Jade G. Chan, Anna Joe, Yan Chen, Youssef Belkhadir, Christopher J. Petzold, and Ofir Bahar
- Subjects
0106 biological sciences ,0301 basic medicine ,Immunogen ,Xanthomonas ,medicine.medical_treatment ,ATP-binding cassette transporter ,Peptide ,Immune receptor ,Protein Serine-Threonine Kinases ,01 natural sciences ,03 medical and health sciences ,chemistry.chemical_compound ,Xanthomonas oryzae ,Biosynthesis ,Bacterial Proteins ,medicine ,Receptor ,Plant Proteins ,chemistry.chemical_classification ,Multidisciplinary ,Protease ,biology ,Oryza ,biology.organism_classification ,030104 developmental biology ,chemistry ,Biochemistry ,PNAS Plus ,Genes, Bacterial ,Host-Pathogen Interactions ,ATP-Binding Cassette Transporters ,Peptides ,Metabolic Networks and Pathways ,010606 plant biology & botany ,Peptide Hydrolases - Abstract
The rice immune receptor XA21 is activated by the sulfated microbial peptide required for activation of XA21-mediated immunity X (RaxX) produced by Xanthomonas oryzae pv. oryzae (Xoo). Mutational studies and targeted proteomics revealed that the RaxX precursor peptide (proRaxX) is processed and secreted by the protease/transporter RaxB, the function of which can be partially fulfilled by a noncognate peptidase-containing transporter component B (PctB). proRaxX is cleaved at a Gly-Gly motif, yielding a mature peptide that retains the necessary elements for RaxX function as an immunogen and host peptide hormone mimic. These results indicate that RaxX is a prokaryotic member of a previously unclassified and understudied group of eukaryotic tyrosine sulfated ribosomally synthesized, posttranslationally modified peptides (RiPPs). We further demonstrate that sulfated RaxX directly binds XA21 with high affinity. This work reveals a complete, previously uncharacterized biological process: bacterial RiPP biosynthesis, secretion, binding to a eukaryotic receptor, and triggering of a robust host immune response.
- Published
- 2019