title: Symbiotic rhizobia bacteria trigger a change in localization and dynamics of the Medicago truncatula receptor kinase LYK3.
abstract: To form nitrogen-fixing symbioses, legume plants recognize a bacterial signal, Nod Factor (NF). The legume Medicago truncatula has two predicted NF receptors that direct separate downstream responses to its symbiont Sinorhizobium meliloti. NOD FACTOR PERCEPTION encodes a putative low-stringency receptor that is responsible for calcium spiking and transcriptional responses. LYSIN MOTIF RECEPTOR-LIKE KINASE3 (LYK3) encodes a putative high-stringency receptor that mediates bacterial infection. We localized green fluorescent protein (GFP)-tagged LYK3 in M. truncatula and found that it has a punctate distribution at the cell periphery consistent with a plasma membrane or membrane-tethered vesicle localization. In buffer-treated control roots, LYK3:GFP puncta are dynamic. After inoculation with compatible S. meliloti, LYK3:GFP puncta are relatively stable. We show that increased LYK3:GFP stability depends on bacterial NF and NF structure but that NF is not sufficient for the change in LYK3:GFP dynamics. In uninoculated root hairs, LYK3:GFP has little codistribution with mCherry-tagged FLOTILLIN4 (FLOT4), another punctate plasma membrane-associated protein required for infection. In inoculated root hairs, we observed an increase in FLOT4:mCherry and LYK3:GFP colocalization; both proteins localize to positionally stable puncta. We also demonstrate that the localization of tagged FLOT4 is altered in plants carrying a mutation that inactivates the kinase domain of LYK3. Our work indicates that LYK3 protein localization and dynamics are altered in response to symbiotic bacteria.
authors: Department of Biology, Stanford University, Stanford, California 94305, USA.
authors: Cara H
authors: CH
authors: Haney
authors: Brendan K
authors: BK
authors: Riely
authors: David M
authors: DM
authors: Tricoli
authors: Doug R
authors: DR
authors: Cook
authors: David W
authors: DW
authors: Ehrhardt
authors: Sharon R
authors: SR
authors: Long
mesh_terms: D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D008070:Lipopolysaccharides; D046913:Medicago truncatula / Q000166:cytology / Q000201:enzymology* / Q000382:microbiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009586:Nitrogen Fixation / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016962:Sinorhizobium meliloti / Q000472:pathogenicity / Q000502:physiology*; D013559:Symbiosis / Q000502:physiology*
chemical_list: D008070:Lipopolysaccharides; D008565:Membrane Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; C106354:flotillins; D020794:Receptor Protein-Tyrosine Kinases