Modulation of an RNA-binding protein by abscisic-acid-activated protein kinase.
Protein kinases are involved in stress signalling in both plant and animal systems. The hormone abscisic acid mediates the responses of plants to stresses such as drought, salinity and cold. Abscisic-acid-activated protein kinase (AAPK -- found in guard cells, which control stomatal pores -- has been shown to regulate plasma membrane ion channels. Here we show that AAPK-interacting protein 1 (AKIP1), with sequence homology to heterogeneous nuclear RNA-binding protein A/B, is a substrate of AAPK. AAPK-dependent phosphorylation is required for the interaction of AKIP1 with messenger RNA that encodes dehydrin, a protein implicated in cell protection under stress conditions. AAPK and AKIP1 are present in the guard-cell nucleus, and in vivo treatment of such cells with abscisic acid enhances the partitioning of AKIP1 into subnuclear foci which are reminiscent of nuclear speckles. These results show that phosphorylation-regulated RNA target discrimination by heterogeneous nuclear RNA-binding proteins may be a general phenomenon in eukaryotes, and implicate a plant hormone in the regulation of protein dynamics during rapid subnuclear reorganization.
Biology Department, The Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania 16802, USA. jiax_li@hms.harvard.edu
Jiaxu
J
Li
Toshinori
T
Kinoshita
Sona
S
Pandey
Carl K-Y
CK
Ng
Steven P
SP
Gygi
Ken-ichiro
K
Shimazaki
Sarah M
SM
Assmann
D000040:Abscisic Acid / Q000494:pharmacology*; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D007887:Fabaceae / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques
D010937:Plant Growth Regulators; D010940:Plant Proteins; D018749:RNA, Plant; D016601:RNA-Binding Proteins; C070556:dehydrin proteins, plant; D000040:Abscisic Acid; D017346:Protein Serine-Threonine Kinases
Non-programmatic