title: Small protein-mediated quorum sensing in a Gram-negative bacterium.
abstract: The rice XA21 pattern recognition receptor binds a type I secreted sulfated peptide, called axY(S)22, derived from the Ax21 (activator of XA21-mediated immunity) protein. The conservation of Ax21 in all sequenced Xanthomonas spp. and closely related genera suggests that Ax21 serves a key biological function. Here we show that the predicted N-terminal sequence of Ax21 is cleaved prior to secretion outside the cell and that mature Ax21 serves as a quorum sensing (QS) factor in Xanthomonas oryzae pv. oryzae. Ax21-mediated QS controls motility, biofilm formation and virulence. We provide genetic evidence that the Xoo RaxH histidine kinase serves as the bacterial receptor for Ax21. This work establishes a critical role for small protein-mediated QS in a Gram-negative bacterium.
authors.affiliation: Department of Plant Pathology and the Genome Center, University of California Davis, Davis, California, United States of America.
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Han
authors.forename: Malinee
authors.initials: M
authors.lastname: Sriariyanun
authors.forename: Sang-Won
authors.initials: SW
authors.lastname: Lee
authors.forename: Manoj
authors.initials: M
authors.lastname: Sharma
authors.forename: Ofir
authors.initials: O
authors.lastname: Bahar
authors.forename: Zachary
authors.initials: Z
authors.lastname: Bower
authors.forename: Pamela C
authors.initials: PC
authors.lastname: Ronald
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms; D016680:Genome, Bacterial / Q000235:genetics; D006090:Gram-Negative Bacteria / Q000166:cytology / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D053038:Quorum Sensing; D011994:Recombinant Proteins / Q000302:isolation & purification; D059467:Transcriptome / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins