title: Functional domain analysis of the Remorin protein LjSYMREM1 in Lotus japonicus.
abstract: In legumes rhizobial infection during root nodule symbiosis (RNS) is controlled by a conserved set of receptor proteins and downstream components. MtSYMREM1, a protein of the Remorin family in Medicago truncatula, was shown to interact with at least three receptor-like kinases (RLKs) that are essential for RNS. Remorins are comprised of a conserved C-terminal domain and a variable N-terminal region that defines the six different Remorin groups. While both N- and C-terminal regions of Remorins belonging to the same phylogenetic group are similar to each other throughout the plant kingdom, the N-terminal domains of legume-specific group 2 Remorins show exceptional high degrees of sequence divergence suggesting evolutionary specialization of this protein within this clade. We therefore identified and characterized the MtSYMREM1 ortholog from Lotus japonicus (LjSYMREM1), a model legume that forms determinate root nodules. Here, we resolved its spatio-temporal regulation and showed that over-expression of LjSYMREM1 increases nodulation on transgenic roots. Using a structure-function approach we show that protein interactions including Remorin oligomerization are mainly mediated and stabilized by the Remorin C-terminal region with its coiled-coil domain while the RLK kinase domains transiently interact in vivo and phosphorylate a residue in the N-terminal region of the LjSYMREM1 protein in vitro. These data provide novel insights into the mechanism of this putative molecular scaffold protein and underline its importance during rhizobial infection.
authors.affiliation: Department of Genetics, University of Munich, Martinsried, Germany.
authors.forename: Katalin
authors.initials: K
authors.lastname: Tóth
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Stratil
authors.forename: Esben B
authors.initials: EB
authors.lastname: Madsen
authors.forename: Juanying
authors.initials: J
authors.lastname: Ye
authors.forename: Claudia
authors.initials: C
authors.lastname: Popp
authors.forename: Meritxell
authors.initials: M
authors.lastname: Antolín-Llovera
authors.forename: Christina
authors.initials: C
authors.lastname: Grossmann
authors.forename: Ole N
authors.initials: ON
authors.lastname: Jensen
authors.forename: Arthur
authors.initials: A
authors.lastname: Schüssler
authors.forename: Martin
authors.initials: M
authors.lastname: Parniske
authors.forename: Thomas
authors.initials: T
authors.lastname: Ott
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D019143:Evolution, Molecular; D007887:Fabaceae / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D049810:Genetic Speciation; D000070116:Lotus / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D046913:Medicago truncatula / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified; D011485:Protein Binding; D055503:Protein Multimerization / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000502:physiology; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013559:Symbiosis / Q000235:genetics / Q000502:physiology; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D010750:Phosphoproteins; D010940:Plant Proteins; C103794:remorin