Photoaffinity labeling of Arabidopsis thaliana plasma membrane vesicles by 5-azido-[7-3H]indole-3-acetic acid: identification of a glutathione S-transferase.
We used 5-azido-[7-3H]indole-3-acetic acid (5-azido-[7-3H]IAA), a photoaffinity analogue of the plant hormone indole-3-acetic acid (IAA), to search for auxin-binding proteins in Arabidopsis thaliana membranes. We identified an auxin-binding protein with a molecular mass of 24 kDa (Atpm24) in microsomes as well as in plasma membrane vesicles. Atpm24 was solubilized by 1% Triton X-100 and partially purified. A cDNA clone (Atpm24.1) corresponding to Atpm24 was isolated. The amino acid sequence predicted from the Atpm24.1 cDNA contains 212 amino acid residues with a relative molecular mass of 24,128 Da. Data base searches revealed that the predicted protein has homology to glutathione S-transferases (GSTs; EC 2.5.1.18). When Atpm24.1 was expressed in Escherichia coli, we found a high level of GST activity in the bacterial extracts. We have analyzed the substrate specificity of this protein and found that cumene hydroperoxide and trans-stilbene oxide but not trans-cinnamic acid or IAA-CoA were substrates. A role for this GST in physiological processes of plants is discussed.
Zettl
R
R
Max-Planck-Institut für Züchtungsforschung, Cologne, Federal Republic of Germany.
Schell
J
J
Palme
K
K
D000345:Affinity Labels; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001386:Azides; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005982:Glutathione Transferase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010937:Plant Growth Regulators; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D000345:Affinity Labels; D001386:Azides; D017931:DNA Primers; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C046131:auxin receptor, plant; C068520:5-azido-1H-indole-3-acetic acid; D005982:Glutathione Transferase