Leucine-rich repeat receptor kinases in plants: structure, function, and signal transduction pathways.
Leucine-rich repeat receptor kinases (LRR-RKs) comprise the largest subfamily of transmembrane receptor-like kinases in plants, with over 200 members in Arabidopsis. LRR-RKs regulate a wide variety of developmental and defense-related processes including cell proliferation, stem cell maintenance, hormone perception, host-specific as well as non-host-specific defense response, wounding response, and symbiosis. Several studies indicate that LRR-RKs act as dimers, and some may form a receptor complex with leucine-rich repeat receptor-like proteins (LRR-RPs) that lack a cytoplasmic kinase domain. Despite the fact that structural features of LRR-RKs are fairy similar, five available ligand molecules for LRR-RKs are structurally diverse, from steroids (brassinolides) to peptides (phytosulfokine and systemin) and secreted proteins (CLV3). Precise ligand-binding sites of LRR-RKs are not understood. However, the extracellular "island" domain that intercepts the LRR domain in some LRR-RKs may play an important role in ligand binding. Advances in unveiling components of three LRR-RK signaling pathways, namely BRI1 in steroid signaling, CLV1 in meristem maintenance, and FLS2 in bacterial elicitor perception, revealed an intriguing link between plant LRR-RK and animal receptor signaling pathways. Finally, rapid progress made in LRR-RK research beyond the model system Arabidopsis has provided exciting, novel insights into the evolution of the LRR-RK signaling system in plants, such as BRI1 utilized in the wound-responsive signaling pathway in Solanaceae plants and recruitment of CLV1 in nodule development in leguminous plants.
Torii
Keiko U
KU
Department of Biology, University of Washington, Seattle, Washington 98195, USA.
D001665:Binding Sites / Q000502:physiology; D008024:Ligands; D063245:Plant Development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000201:enzymology* / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
D008024:Ligands; D010940:Plant Proteins; D011494:Protein Kinases