title: AKINbetagamma contributes to SnRK1 heterotrimeric complexes and interacts with two proteins implicated in plant pathogen resistance through its KIS/GBD sequence.
abstract: 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.
authors.affiliation: Institut de Biotechnologie des Plantes, Unité Mixte de Recherche Centre National de la Recherche Scientifique 8618, Université Paris-Sud, F-91405 Orsay cedex, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Gissot
authors.forename: Cécile
authors.initials: C
authors.lastname: Polge
authors.forename: Mathieu
authors.initials: M
authors.lastname: Jossier
authors.forename: Thomas
authors.initials: T
authors.lastname: Girin
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Bouly
authors.forename: Martin
authors.initials: M
authors.lastname: Kreis
authors.forename: Martine
authors.initials: M
authors.lastname: Thomas
mesh_terms: 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
chemical_list: C516466:AKINbeta1 protein, Arabidopsis; C516467:AKINbeta2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D011494:Protein Kinases