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Title: Flagellin peptide flg22 gains access to long-distance trafficking in Arabidopsis via its receptor, FLS2

Abstract

Diverse pathogen-derived molecules, such as bacterial flagellin and its conserved peptide flg22, are recognized in plants via plasma membrane receptors and induce both local and systemic immune responses. The fate of such ligands was unknown: whether and by what mechanism(s) they enter plant cells and whether they are transported to distal tissues. We used biologically active fluorophore and radiolabeled peptides to establish that flg22 moves to distal organs with the closest vascular connections. Remarkably, entry into the plant cell via endocytosis together with the FLS2 receptor is needed for delivery to vascular tissue and long-distance transport of flg22. This contrasts with known routes of long distance transport of other non-cell-permeant molecules in plants, which require membrane-localized transporters for entry to vascular tissue. Thus, a plasma membrane receptor acts as a transporter to enable access of its ligand to distal trafficking routes.

Authors:
 [1];  [2];  [3];  [2];  [1]
  1. Univ. of Chicago, IL (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1394455
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Experimental Botany
Additional Journal Information:
Journal Volume: 68; Journal Issue: 7; Journal ID: ISSN 0022-0957
Publisher:
Oxford University Press
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES

Citation Formats

Jelenska, Joanna, Davern, Sandra M., Standaert, Robert F., Mirzadeh, Saed, and Greenberg, Jean T. Flagellin peptide flg22 gains access to long-distance trafficking in Arabidopsis via its receptor, FLS2. United States: N. p., 2017. Web. doi:10.1093/jxb/erx060.
Jelenska, Joanna, Davern, Sandra M., Standaert, Robert F., Mirzadeh, Saed, & Greenberg, Jean T. Flagellin peptide flg22 gains access to long-distance trafficking in Arabidopsis via its receptor, FLS2. United States. doi:10.1093/jxb/erx060.
Jelenska, Joanna, Davern, Sandra M., Standaert, Robert F., Mirzadeh, Saed, and Greenberg, Jean T. Wed . "Flagellin peptide flg22 gains access to long-distance trafficking in Arabidopsis via its receptor, FLS2". United States. doi:10.1093/jxb/erx060. https://www.osti.gov/servlets/purl/1394455.
@article{osti_1394455,
title = {Flagellin peptide flg22 gains access to long-distance trafficking in Arabidopsis via its receptor, FLS2},
author = {Jelenska, Joanna and Davern, Sandra M. and Standaert, Robert F. and Mirzadeh, Saed and Greenberg, Jean T.},
abstractNote = {Diverse pathogen-derived molecules, such as bacterial flagellin and its conserved peptide flg22, are recognized in plants via plasma membrane receptors and induce both local and systemic immune responses. The fate of such ligands was unknown: whether and by what mechanism(s) they enter plant cells and whether they are transported to distal tissues. We used biologically active fluorophore and radiolabeled peptides to establish that flg22 moves to distal organs with the closest vascular connections. Remarkably, entry into the plant cell via endocytosis together with the FLS2 receptor is needed for delivery to vascular tissue and long-distance transport of flg22. This contrasts with known routes of long distance transport of other non-cell-permeant molecules in plants, which require membrane-localized transporters for entry to vascular tissue. Thus, a plasma membrane receptor acts as a transporter to enable access of its ligand to distal trafficking routes.},
doi = {10.1093/jxb/erx060},
journal = {Journal of Experimental Botany},
number = 7,
volume = 68,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}

Journal Article:
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  • Microbe-associated molecular patterns (MAMPs) are molecules, or domains within molecules, that are conserved across microbial taxa and can be recognized by a plant or animal immune system. Although MAMP receptors have evolved to recognize conserved epitopes, the MAMPs in some microbial species or strains have diverged sufficiently to render them unrecognizable by some host immune systems. In this study, we carried out in vitro evolution of the Arabidopsis thaliana flagellin receptor FLAGELLIN-SENSING 2 (FLS2) to isolate derivatives that recognize one or more flagellin peptides from bacteria for which the wildtype Arabidopsis FLS2 confers little or no response. A targeted approachmore » generated amino acid variation at FLS2 residues in a region previously implicated in flagellin recognition. The primary screen tested for elevated response to the canonical flagellin peptide from Pseudomonas aeruginosa, flg22. From this pool, we then identified five alleles of FLS2 that confer modest (quantitatively partial) recognition of an Erwinia amylovora flagellin peptide. Use of this Erwinia-based flagellin peptide to stimulate Arabidopsis plants expressing the resulting FLS2 alleles did not lead to a detectable reduction of virulent P. syringae pv. tomato growth. However, combination of two identified mutations into a single allele further increased FLS2-mediated responses to the E. amylovora flagellin peptide. Furthermore, these studies demonstrate the potential to raise the sensitivity of MAMP receptors toward particular targets.« less
  • Microbe-associated molecular patterns (MAMPs) are molecules, or domains within molecules, that are conserved across microbial taxa and can be recognized by a plant or animal immune system. Although MAMP receptors have evolved to recognize conserved epitopes, the MAMPs in some microbial species or strains have diverged sufficiently to render them unrecognizable by some host immune systems. In this study, we carried out in vitro evolution of the Arabidopsis thaliana flagellin receptor FLAGELLIN-SENSING 2 (FLS2) to isolate derivatives that recognize one or more flagellin peptides from bacteria for which the wildtype Arabidopsis FLS2 confers little or no response. A targeted approachmore » generated amino acid variation at FLS2 residues in a region previously implicated in flagellin recognition. The primary screen tested for elevated response to the canonical flagellin peptide from Pseudomonas aeruginosa, flg22. From this pool, we then identified five alleles of FLS2 that confer modest (quantitatively partial) recognition of an Erwinia amylovora flagellin peptide. Use of this Erwinia-based flagellin peptide to stimulate Arabidopsis plants expressing the resulting FLS2 alleles did not lead to a detectable reduction of virulent P. syringae pv. tomato growth. However, combination of two identified mutations into a single allele further increased FLS2-mediated responses to the E. amylovora flagellin peptide. Furthermore, these studies demonstrate the potential to raise the sensitivity of MAMP receptors toward particular targets.« less
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  • Electron transfer is one of the fundamental reactions in biological photosynthesis, respiration, and redox-mediated enzyme catalysis. Understanding the role of peptides and proteins in mediating long-range electron transfer has important physical, chemical, and biological implications. Intramolecular electron-transfer reactions, where electron transfer occurs between donor and acceptor sites separated by a synthetic peptide or protein fragment, have so far provided the most insight into the role of the peptide and protein in mediating electron transfer. This article reviews the work the authors' group and others on small molecule systems that have been designed and studied to explore long-range electron-transfer pathways availablemore » between a donor and an acceptor separated by a rigid peptide framework. The role of the secondary structure of polyproline II in facilitating these mediations is explored. 87 refs., 3 figs, 5 tabs.« less
  • Interleukin-8 (CXCL8, IL-8) is a pro-inflammatory chemokine important for the regulation of inflammatory and immune responses via its interaction with G-protein coupled receptors, including CXC receptor 1 (CXCR1). CXCL8 exists as both a monomer and as a dimer at physiological concentrations, yet the molecular basis of CXCL8 interaction with its receptor as well as the importance of CXCL8 dimer formation remain poorly characterized. Although several biological studies have indicated that both the CXCL8 monomer and dimer are active, biophysical studies have reported conflicting results regarding the binding of CXCL8 to CXCR1. To clarify this problem, we expressed and purified amore » peptide (hCXCR1pep) corresponding to the N-terminal region of human CXCR1 (hCXCR1) and utilized nuclear magnetic resonance (NMR) spectroscopy to interrogate the binding of wild-type CXCL8 and a previously reported mutant (CXCL8M) that stabilizes the monomeric form. Our data reveal that CXCL8M engages hCXCR1pep with a slightly higher affinity than CXCL8, and that CXCL8 does not dissociate upon binding hCXCR1pep. These investigations also indicate that CXCL8 exhibits inherent flexibility within its receptor-binding site on multiple timescales, which may help explain the versatility in this interleukin for engaging its target receptors.« less