title: Distinct signaling mechanisms in multiple developmental pathways by the SCRAMBLED receptor of Arabidopsis.
abstract: SCRAMBLED (SCM), a leucine-rich repeat receptor-like kinase in Arabidopsis (Arabidopsis thaliana), is required for positional signaling in the root epidermis and for tissue/organ development in the shoot. To further understand SCM action, we generated a series of kinase domain variants and analyzed their ability to complement scm mutant defects. We found that the SCM kinase domain, but not kinase activity, is required for its role in root epidermal patterning, supporting the view that SCM is an atypical receptor kinase. We also describe a previously uncharacterized role for SCM in fruit dehiscence, because mature siliques from scm mutants fail to open properly. Interestingly, the kinase domain of SCM appears to be dispensable for this developmental process. Furthermore, we found that most of the SCM kinase domain mutations dramatically inhibit inflorescence development. Because this process is not affected in scm null mutants, it is likely that SCM acts redundantly to regulate inflorescence size. The importance of distinct kinase residues for these three developmental processes provides an explanation for the maintenance of the conserved kinase domain in the SCM protein, and it may generally explain its conservation in other atypical kinases. Furthermore, these results indicate that individual leucine-rich repeat receptor-like kinases may participate in multiple pathways using distinct signaling mechanisms to mediate diverse cellular communication events.
authors.affiliation: Biology Department, Long Island University, Brooklyn, New York 11201 (S.-H.K.);Department of Systems Biology, Yonsei University, Seoul 120-749, Korea (S.W., M.M.L.); andDepartment of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (J.S.) su-hwan.kwak@liu.edu.
authors.forename: Su-Hwan
authors.initials: SH
authors.lastname: Kwak
authors.affiliation: Biology Department, Long Island University, Brooklyn, New York 11201 (S.-H.K.);Department of Systems Biology, Yonsei University, Seoul 120-749, Korea (S.W., M.M.L.); andDepartment of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (J.S.).
authors.forename: Sooah
authors.initials: S
authors.lastname: Woo
authors.affiliation: Biology Department, Long Island University, Brooklyn, New York 11201 (S.-H.K.);Department of Systems Biology, Yonsei University, Seoul 120-749, Korea (S.W., M.M.L.); andDepartment of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (J.S.).
authors.forename: Myeong Min
authors.initials: MM
authors.lastname: Lee
authors.affiliation: Biology Department, Long Island University, Brooklyn, New York 11201 (S.-H.K.);Department of Systems Biology, Yonsei University, Seoul 120-749, Korea (S.W., M.M.L.); andDepartment of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109 (J.S.).
authors.forename: John
authors.initials: J
authors.lastname: Schiefelbein
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D049452:Green Fluorescent Proteins; D020794:Receptor Protein-Tyrosine Kinases; C503317:SUB protein, Arabidopsis