title: Site-specific N-glycosylation of the S-locus receptor kinase and its role in the self-incompatibility response of the brassicaceae.
abstract: The S-locus receptor kinase SRK is a highly polymorphic transmembrane kinase of the stigma epidermis. Through allele-specific interaction with its pollen coat-localized ligand, the S-locus cysteine-rich protein SCR, SRK is responsible for recognition and inhibition of self pollen in the self-incompatibility response of the Brassicaceae. The SRK extracellular ligand binding domain contains several potential N-glycosylation sites that exhibit varying degrees of conservation among SRK variants. However, the glycosylation status and functional importance of these sites are currently unclear. We investigated this issue in transgenic Arabidopsis thaliana stigmas that express the Arabidopsis lyrata SRKb variant and exhibit an incompatible response toward SCRb-expressing pollen. Analysis of single- and multiple-glycosylation site mutations of SRKb demonstrated that, although five of six potential N-glycosylation sites in SRKb are glycosylated in stigmas, N-glycosylation is not important for SCRb-dependent activation of SRKb. Rather, N-glycosylation functions primarily to ensure the proper and efficient subcellular trafficking of SRK to the plasma membrane. The study provides insight into the function of a receptor that regulates a critical phase of the plant life cycle and represents a valuable addition to the limited information available on the contribution of N-glycosylation to the subcellular trafficking and function of plant receptor kinases.
authors.affiliation: Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850.
authors.forename: Masaya
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850.
authors.forename: Titima
authors.initials: T
authors.lastname: Tantikanjana
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-855, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishio
authors.affiliation: Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850.
authors.forename: Mikhail E
authors.initials: ME
authors.lastname: Nasrallah
authors.affiliation: Section of Plant Biology, School of Integrative Plant Science, Cornell University, Ithaca, New York 14850 jbn2@cornell.edu.
authors.forename: June B
authors.initials: JB
authors.lastname: Nasrallah
mesh_terms: D020816:Amino Acid Motifs; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D006031:Glycosylation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology; D011058:Pollen / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D060436:Self-Incompatibility in Flowering Plants / Q000235:genetics
chemical_list: D010940:Plant Proteins; D011494:Protein Kinases; C079832:S-receptor kinase