OsCERK1

Annotated Information

Function

• Rice cells require a LysM receptor-like kinase, OsCERK1, in addition to CEBiP, for chitin signaling. Knockdown ofOsCERK1resulted in marked suppression of the defense responses induced by chitin oligosaccharides, indicating that OsCERK1 is essential for chitin signaling in rice.
• The results of a yeast two-hybrid assay indicated that both CEBiP and OsCERK1 have the potential to form hetero- or homo-oligomers. Immunoprecipitation using a membrane preparation from rice cells treated with chitin oligosaccharides suggested the ligand-induced formation of a receptor complex containing both CEBiP and OsCERK1.
• Our studies show that chitin, chitin oligomers, and chitosan rapidly induce in vivophosphorylation

of CERK1 at multiple residues in the juxtamembrane and kinase domain. Functional analyses with a kinase dead variant provide evidence that kinase activity of CERK1 is required for its chitin-dependent in vivophosphorylation, as well as for early defense responses and downstream signaling.

• The CERK1 ectodomain binds chitin and partially deacetylated chitosan directly without any

requirement for interacting proteins and that all three LysM domains are necessary for chitin binding.

Localization

• OsLysM-RLK9(designated OsCERK1hereafter) encoded a receptor-like kinase consisting of 624 amino acid residues, containing a signal peptide, an extracellular domain, a transmembrane region and an intracellular Ser/Thr kinase domain. Motif analysis indicated the presence of one LysM motif in the OsCERK1 extracellular domain, while CERK1 contained three LysM motifs in its extracellular domain (Miya et al., 2007).
• In the LysM motif of OsCERK1, 54.8% of the amino acid residues were identical to those of the third LysM motif (LysM3, 42 amino acids) of CERK1 . Interestingly, the corresponding regions of the amino acid sequence of the OsCERK1 extracellular domain also showed significant similarity with the other two LysM motifs of CERK1; 24.5% identity with LysM1 and 43% with LysM2 . However, these regions in OsCERK1 were not identified as LysM motifs by the motif database analysis. The amino acid sequence of the intracellular Ser/Thr kinase domain of OsCERK1 showed a very high similarity with that of CERK1,with 64% identical residues.
• OsCERK1was expressed in all tissues tested, with weak expression in the flowers . Interestingly, the expression pattern ofOsCERK1in plants was very similar to that of CEBiP, except for the weak expression

in the flowers (Kakuet al., 2006).

Expression

• Three RNAiOsCERK1knockdown cell lines were generated to investigate the function of OsCERK1. Transcriptional analyses of the knockdown cell lines showed that expression ofOsCERK1was markedly

reduced but expression of the otherOsLysM-RLKgenes and theCEBiPgene was not affected in these cell lines.

• Chitin oligosaccharide elicitor is known to induce biphasic generation of reactive oxygen species

(ROS) in rice suspension cell cultures. The first peak of ROS at approximately 30 min after elicitor treatment does not require protein synthesis, but the latter peak at approximately 2 h does require protein synthesis (Yamaguchi et al., 2005).

• Both peaks of chitin oligosaccharide-induced ROS generation were markedly decreased in allOsCERK1-RNAi cell lines compared to vector control (VC) cells. On the other hand, ROS generation induced by a bacterial lipopolysaccharide (LPS) (Desakiet al., 2006) was not affected in these OsCERK1-RNAi cell lines , although the amount of ROS accumulated varied between the cell lines.
• These results indicate that knockdown ofOsCERK1specifically affected the chitin-induced ROS generation of rice cells.
• Here, we identified a receptor-like kinase, designated CERK1, which is essential for chitin elicitor signaling in Arabidopsis. The KO mutants for CERK1 completely lost the ability to respond to the chitin elicitor, including MAPK activation, reactive oxygen species generation, and gene expression. Disease resistance of the KO mutant against an incompatible fungus, Alternaria brassicicola, was partly impaired. Complementation with the WT CERK1 gene showed cerk1 mutations were responsible for the mutant phenotypes.

Catalytic activity

ATP + a protein = ADP + a phosphoprotein.

Labs working on this gene

• Department of Life Sciences; 1-1-1 Higashi-Mita, Tama-ku, Kawasaki,Kanagawa 214-8571, Japan
• The Sainsbury Laboratory, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom
• Department of Plant Cell Biology, Albrecht-von-Haller-Institute of Plant Sciences, Georg-August-University Goettingen, Untere Karspuele 2, D-37073 Goettingen, Germany
• Department of Life Sciences, Faculty of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa214-8571, Japan,
• Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602,Japan

References

• Nürnberger T., Kemmerling B. (2006) Trends Plant Sci. 11, 519–522 CrossRefMedlineSearch Google Scholar
• Boller T., Felix G. (2009) Annu. Rev. Plant Biol. 60, 379–406 CrossRefMedlineSearch Google Scholar
• Kim, T.W. and Wang, Z.Y.(2010) Brassinosteroid signal transduction from receptor kinases to transcription factors.Annu. Rev. Plant Biol.61, 681–704.

Structured information

Gene Name	OsCERK1
Description	LysM receptor-like kinase
Version	'
Length	bp
Definition	chitin elicitor receptor kinase
Source	Oryza sativa Japonica Group
Chromosome	Chromosome
Location	{{{AP}}}
Sequence Coding Region	{{{CDS}}}
Expression	GEO Profiles:OsCERK1
Genome Context	{{{GCID}}}
Gene Structure	{{{GSID}}}
Coding Sequence	<cdnaseq></cdnaseq>
Protein Sequence	<aaseq></aaseq>
Gene Sequence	{{{DNA}}}
External Link(s)	NCBI Gene:OsCERK1, {{{Link}}}