AKINbeta3, a plant specific SnRK1 protein, is lacking domains present in yeast and mammals non-catalytic beta-subunits.
The SNF1/AMPK/SnRK1 heterotrimeric kinase complex is involved in the adaptation of cellular metabolism in response to diverse stresses in yeast, mammals and plants. Following a model proposed in yeast, the kinase targets are likely to bind the complex via the non-catalytic beta-subunits. These proteins currently identified in yeast, mammals and plants present a common structure with two conserved interacting domains named Kinase Interacting Sequence (KIS) and Association with SNF1 Complex (ASC), and a highly variable N-terminal domain. In this paper we describe the characterisation of AKINbeta3, a novel protein related to AKINbeta subunits of Arabidopsis thaliana, containing a truncated KIS domain and no N-terminal extension. Interestingly the missing region of the KIS domain corresponds to the glycogen-binding domain (beta-GBD) identified in the mammalian AMPKbeta1. In spite of its unusual features, AKINbeta3 complements the yeast sip1Deltasip2Deltagal83Delta mutant. Moreover, interactions between AKINbeta3 and other AKIN complex subunits from A. thaliana were detected by two-hybrid experiments and in vitro binding assays. Taken together these data demonstrate that AKINbeta3 is a beta-type subunit. A search for beta-type subunits revealed the existence of beta3-type proteins in other plant species. Furthermore, we suggest that the AKINbeta3-type subunits could be plant specific since no related sequences have been found in any of the other completely sequenced genomes. These data suggest the existence of novel SnRK1 complexes including AKINbeta3-type subunits, involved in several functions among which some could be plant specific.
Gissot
Lionel
L
Laboratoire de Biologie du Développement des Plantes, Institut de Biotechnologie des Plantes (IBP), UMR CNRS 8618, Bâtiment 630, Université Paris-Sud, F-91405 Orsay Cedex, France.
Polge
Cécile
C
Bouly
Jean-Pierre
JP
Lemaitre
Thomas
T
Kreis
Martin
M
Thomas
Martine
M
D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D015152:Blotting, Northern; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008322:Mammals / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D030821:Plants, Genetically Modified; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
C516466:AKINbeta1 protein, Arabidopsis; C516467:AKINbeta2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D007527:Isoenzymes; D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases