Reference "Cytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts"

Reference ID

7145

Title

Cytokinin oxidase from Zea mays: purification, cDNA cloning and expression in moss protoplasts

Source

The Plant journal : for cell and molecular biology, 1999, vol. 17, pp. 615-626

Authors (4)

Houba-Herin-N	Pethe-C
d'Alayer-J	Laloue-M

Abstract

Cytokinins are degraded by cytokinin oxidases (CKOs) which catalyse cleavage of
the N6-(isopent-2-enyl)-side chain resulting in formation of adenine-type
compounds. CKO activity has been recorded in many plants and is thought to play
a key role in controlling cytokinin levels in plants. Several partially purified
CKOs have been characterised but no genes have been isolated yet. CKO activity
is known to be inhibited by phenylureas, cytokinin agonists. We used 1-(2-azido-6-chloropyrid-4-yl)-3-(4-
[3H])phenylurea ([3H]-azidoCPPU) to photolabel a glycosylated CKO from maize
kernels. This enabled us to purify the enzyme. Peptide sequences were determined
and the corresponding cDNA was cloned. The deduced amino acid sequence shares
homology domains with FAD-dependent oxidases. An original assay based on
transient expression of the enzyme in moss protoplasts allowed the functionality
of the recombinant enzyme to be demonstrated.