Identification of SnIP1, a novel protein that interacts with SNF1-related protein kinase (SnRK1).
Plant SNF1-related protein kinase (SnRK1) phosphorylates 3-hydroxy-3-methylglutaryl-Coenzyme A, nitrate reductase and sucrose phosphate synthase in vitro, and is required for expression of sucrose synthase in potato tubers and excised leaves. In this study, a barley (Hordeum vulgare) endosperm cDNA, SnIP1, was isolated by two-hybrid screening with barley SnRK1b, a seed-specific form of SnRK1. The protein encoded by the SnIP1 cDNA was found to interact with barley SnRK1b protein in vitro. Southern analysis suggested that barley contains a single SnIP1 gene or small gene family. SnIP1 transcripts were detected in RNA isolated from leaf, root and mid-maturation seed. Sequence similarity searches against protein, nucleotide and expressed sequence tag databases identified hitherto uncharacterized sequences related to SnIP1 from maize (Zea mays, accession number AI691404), arabidopsis (Arabidopsis thaliana. AC079673 and AB016886) and poplar (Populus balsamifera, AI166543). No homologous sequences were identified from outside the plant kingdom, but weak sequence similarity was found between the SnIP1 peptide and yeast (Saccharomyces cerevisiae) SNF4 and its mammalian homologue AMPKy. Nevertheless, SnIP1 failed to complement a yeast snf4 mutant. SnIP1 was found to have little overall sequence similarity with the PV42 family of SNF4-like plant proteins, but proteins of both the SnIP1 and PV42 families contain a conserved hydrophobic sequence we named the SnIP motif.
Slocombe
Stephen P
SP
IACR-long Ashton Research Station, Department of Agricultural Sciences, University of Bristol, Long Ashton, UK.
Laurie
Sophie
S
Bertini
Laura
L
Beaudoin
Frederic
F
Dickinson
J Richard
JR
Halford
Nigel G
NG
D055372:AMP-Activated Protein Kinases; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D005816:Genetic Complementation Test; D001467:Hordeum / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D002352:Carrier Proteins; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D011494:Protein Kinases; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases; C078651:SNF4 protein, S cerevisiae; D055372:AMP-Activated Protein Kinases