title: Molecular characterisation and regulation of a Nicotiana tabacum S-domain receptor-like kinase gene induced during an early rapid response to lipopolysaccharides.
abstract: The isolation, characterization and regulation of the first lipopolysaccharide (LPS)-responsive S-domain receptor-like kinase (RLK) in Nicotiana tabacum are reported. The gene, corresponding to a differentially expressed LPS-responsive EST, was fully characterised to investigate its involvement in LPS-induced responses. The full genomic sequence, designated Nt-Sd-RLK, encodes for a S-domain RLK protein containing conserved modules (B-lectin-, S- and PAN-domains) reported to function in mediating protein-protein and protein-carbohydrate interactions in its extracellular domain, as well as the molecular architecture to transduce signals intracellularly through a Ser/Thr kinase domain. Phylogenetic analysis clustered Nt-Sd-RLK with S-domain RLKs induced by bacteria, wounding and salicylic acid. Perception of LPS induced a rapid, bi-phasic response in Nt-Sd-RLK expression with a 17-fold up-regulation at 3 and 9h. A defence-related W-box cis element was found in the promoter region of Nt-Sd-RLK and the transient induction of Nt-Sd-RLK in cultured cells by LPS exhibited a pattern typical of early response defence genes. Nt-Sd-RLK was also responsive to salicylic acid induction and was expressed in differentiated leaf tissue, where LPS elicited local as well as systemic up-regulation. The results contribute new knowledge about the potential role that S-domain RLKs may play within interactive signal transduction pathways associated with immunity and defence.
authors.affiliation: Department of Biochemistry, University of Johannesburg, Auckland Park, South Africa.
authors.forename: Natasha M
authors.initials: NM
authors.lastname: Sanabria
authors.forename: Henriëtte
authors.initials: H
authors.lastname: van Heerden
authors.forename: Ian A
authors.initials: IA
authors.lastname: Dubery
mesh_terms: D002478:Cells, Cultured; D020224:Expressed Sequence Tags; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000235:genetics*; D014026:Nicotiana / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D008070:Lipopolysaccharides; D011494:Protein Kinases