Reference "Molecular and biochemical characterization of a cytokinin oxidase from maize"

Reference ID

7147

Title

Molecular and biochemical characterization of a cytokinin oxidase from maize

Source

Plant physiology, 2001, vol. 125, pp. 378-386

Authors (7)

Bilyeu-K-D	Cole-J-L
Laskey-J-G	Riekhof-W-R
Esparza-T-J	Kramer-M-D
Morris-R-O

Abstract

It is generally accepted that cytokinin oxidases, which oxidatively remove
cytokinin side chains to produce adenine and the corresponding isopentenyl
aldehyde, play a major role in regulating cytokinin levels in planta. Partially
purified fractions of cytokinin oxidase from various species have been studied
for many years, but have yet to clearly reveal the properties of the enzyme or
to define its biological significance. Details of the genomic organization of
the recently isolated maize (Zea mays) cytokinin oxidase gene (ckx1) and some of
its Arabidopsis homologs are now presented. Expression of an intronless ckx1 in
Pichia pastoris allowed production of large amounts of recombinant cytokinin
oxidase and facilitated detailed kinetic and cofactor analysis and comparison
with the native enzyme. The enzyme is a flavoprotein containing covalently bound
flavin adenine dinucleotide, but no detectable heavy metals. Expression of the
oxidase in maize tissues is described.