In plants, clade A type 2 C protein phosphatases(PP2 CAs) have emerged as major players in abscisic acid(ABA)-regulated stress responses by inhibiting protein kinase activity. However, how different internal and exter...In plants, clade A type 2 C protein phosphatases(PP2 CAs) have emerged as major players in abscisic acid(ABA)-regulated stress responses by inhibiting protein kinase activity. However, how different internal and external environmental signals modulate the activity of PP2 CAs are not well known. The transmembrane kinase(TMK) protein4(TMK4), one member of a previously identified receptor kinase subfamily on the plasma membrane that plays vital roles in plant cell growth,directly interacts with PP2 CAs member(ABAInsensitive 2, ABI2). tmk4 mutant is hypersensitive to ABA in both ABA-inhibited seed germination and primary root growth, indicating that TMK4 is a negative regulator in ABA signaling pathway.Further analyses indicate that TMK4 phosphorylates ABI2 at three conserved Ser residues,thus enhancing the activity of ABI2. The phosphorylation-mimic ABI2~(S139DS140DS266D)can complement butnon-phosphorylated form ABI2~(S139AS140AS266) Acannot complement ABA hypersensitive phenotype of the loss-of-function mutant abi1-2 abi2-2. This study provides a previously unidentified mechanism for positively regulating ABI2 by a plasma membrane protein kinase.展开更多
基金supported by the National Natural Science Foundation of China(Nos.31571635,31871595,31871396,32070769)the Hunan Provincial Science and Technology Department(No.2018NK1010)+1 种基金The Science and Technology Innovation Program of Hunan Province(No.2020WK2014)the China Tobacco Hunan Industrial Co.,Ltd.Research Project(KY2021YC0001)。
文摘In plants, clade A type 2 C protein phosphatases(PP2 CAs) have emerged as major players in abscisic acid(ABA)-regulated stress responses by inhibiting protein kinase activity. However, how different internal and external environmental signals modulate the activity of PP2 CAs are not well known. The transmembrane kinase(TMK) protein4(TMK4), one member of a previously identified receptor kinase subfamily on the plasma membrane that plays vital roles in plant cell growth,directly interacts with PP2 CAs member(ABAInsensitive 2, ABI2). tmk4 mutant is hypersensitive to ABA in both ABA-inhibited seed germination and primary root growth, indicating that TMK4 is a negative regulator in ABA signaling pathway.Further analyses indicate that TMK4 phosphorylates ABI2 at three conserved Ser residues,thus enhancing the activity of ABI2. The phosphorylation-mimic ABI2~(S139DS140DS266D)can complement butnon-phosphorylated form ABI2~(S139AS140AS266) Acannot complement ABA hypersensitive phenotype of the loss-of-function mutant abi1-2 abi2-2. This study provides a previously unidentified mechanism for positively regulating ABI2 by a plasma membrane protein kinase.
