OsMPK3 is a TEY-type rice MAPK in Group C and phosphorylates OsbHLH65, a transcription factor binding to the E-box element.
OsMPK3 is a TEY-type rice MAPK belonging to Group C and directly phosphorylates OsbHLH65 in the nucleus. OsMPK3 and OsbHLH65 are induced by biotic stress and defense-related hormones. Mitogen-activated protein kinases (MAPKs) are involved in the majority of signaling pathways that regulate plant development and stress tolerance via the phosphorylation of target molecules. Plant MAPKs are classified into two subtypes, TEY and TDY, according to the TxY (x = E or D) motif in their activation loop, and the TDY motif is unique to plant MAPKs. In rice, 17 MAPKs have been classified into six groups. To date, the functions of many TDY-type rice MAPKs have been characterized, but little is known of the TEY-type MAPKs in Group C and their possible target substrates. In the study reported here, we determined that a TEY-type rice MAPK belonging to subgroup C, named OsMPK3, phosphorylates its substrate OsbHLH65 in the nucleus. Our electrophoresis mobility shift assay results revealed that OsbHLH65 specifically binds to the E-box cis-element, but not to the G-box. Both OsMPK3 and OsbHLH65 were induced by treatments with rice blast (Magnaporthe grisea), brown planthopper (Nilaparvata lugens), and defense-related hormones, such as methyl jasmonic acid and salicylic acid. Our results suggest the possibility that OsMPK3 contributes to the defense signal transduction by phosphorylating the basic helix-loop-helix transcription factor.
Division of Life Sciences, Korea University, Seoul, 136-701, Korea.
Hyun-Young
HY
Shin
Min Kyoung
MK
You
Ji Ung
JU
Jeung
Jeong Sheop
JS
Shin
D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D024721:E-Box Elements; D018506:Gene Expression Regulation, Plant; D006430:Hemiptera / Q000502:physiology; D020082:Magnaporthe / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012275:Oryza / Q000166:cytology / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D054883:Oxylipins / Q000494:pharmacology; D010766:Phosphorylation; D010802:Phylogeny; D010935:Plant Diseases / Q000276:immunology*; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D020156:Salicylic Acid / Q000494:pharmacology; D036226:Seedlings / Q000166:cytology / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment; D015398:Signal Transduction; D013312:Stress, Physiological
D051792:Basic Helix-Loop-Helix Proteins; D003517:Cyclopentanes; D020928:Mitogen-Activated Protein Kinases; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D020156:Salicylic Acid; C011006:jasmonic acid