AKINbetagamma contributes to SnRK1 heterotrimeric complexes and interacts with two proteins implicated in plant pathogen resistance through its KIS/GBD sequence.
The sucrose nonfermenting-1 protein kinase (SNF1)/AMP-activated protein kinase subfamily plays a central role in metabolic responses to nutritional and environmental stresses. In yeast (Saccharomyces cerevisiae) and mammals, the beta- and gamma-noncatalytic subunits are implicated in substrate specificity and subcellular localization, respectively, and regulation of the kinase activity. The atypical betagamma-subunit has been previously described in maize (Zea mays), presenting at its N-terminal end a sequence related to the KIS (kinase interacting sequence) domain specific to the beta-subunits (Lumbreras et al., 2001). The existence of two components, SNF1-related protein kinase (SnRK1) complexes containing the betagamma-subunit and one SnRK1 kinase, had been proposed. In this work, we show that, despite its unusual features, the Arabidopsis (Arabidopsis thaliana) homolog AKINbetagamma clearly interacts with AKINbeta-subunits in vitro and in vivo, suggesting its involvement in heterotrimeric complexes located in both cytoplasm and nucleus. Unexpectedly, a transcriptional analysis of AKINbetagamma gene expression highlighted the implication of alternative splicing mechanisms in the regulation of AKINbetagamma expression. A two-hybrid screen performed with AKINbetagamma as bait, together with in planta bimolecular fluorescence complementation experiments, suggests the existence of interactions in the cytosol between AKINbetagamma and two leucine-rich repeats related to pathogen resistance proteins. Interestingly, this interaction occurs through the truncated KIS domain that corresponds exactly to a GBD (glycogen-binding domain) recently described in mammals and yeast. A phylogenetic study suggests that AKINbetagamma-related proteins are restricted to the plant kingdom. Altogether, these data suggest the existence of plant-specific SnRK1 trimeric complexes putatively involved in a plant-specific function such as plant-pathogen interactions.
Gissot
Lionel
L
Institut de Biotechnologie des Plantes, Unité Mixte de Recherche Centre National de la Recherche Scientifique 8618, Université Paris-Sud, F-91405 Orsay cedex, France.
Polge
Cécile
C
Jossier
Mathieu
M
Girin
Thomas
T
Bouly
Jean-Pierre
JP
Kreis
Martin
M
Thomas
Martine
M
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010935:Plant Diseases; D011494:Protein Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary
C516466:AKINbeta1 protein, Arabidopsis; C516467:AKINbeta2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D011494:Protein Kinases