Plant and Cell Physiology Advance Access published online on February 24, 2006
Plant and Cell Physiology, doi:10.1093/pcp/pcj025
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011, Japan
* To whom correspondence should be addressed. Prenylation of the aromatic intermediate p-hydroxybenzoate (PHB) is a critical step in ubiquinone (UQ) biosynthesis. The enzyme that catalyzes this prenylation reaction is PHB polyprenyltransferase (PPT), which substitutes an aromatic proton at the m-position of PHB with a prenyl chain provided by polyprenyl diphosphate synthase. The rice genome contains three PPT candidates that share significant similarity with the yeast PPT (COQ2 gene), and the rice gene showing the highest similarity with COQ2 was isolated by RT-PCR and designated OsPPT1a. The deduced amino acid sequence of OsPPT1a contained a putative mitochondrial sorting signal at the N-terminus and conserved domains for putative substrate-binding sites typical of PPT protein family members. The subcellular localization of OsPPT1a protein was shown to be mainly in mitochondria based on studies using a green fluorescent protein-PPT fusion. A yeast complementation study revealed that OsPPT1a expression successfully recovered the growth defect of coq2 mutant. A prenyltransferase assay using recombinant protein showed that OsPPT1a accepted prenyl diphosphates of various chain lengths as prenyl donors, whereas it showed strict substrate-specificity for the aromatic substrate PHB as a prenyl acceptor. The apparent Km values for geranyl diphosphate and PHB were 59.7 and 6.04 µM, respectively. Their requirement by OsPPT1a for divalent cations was also studied, with Mg2+ found to produce the highest enzyme activity. Northern analysis showed that OsPPT1a mRNA was accumulated in all tissues of O. sativa. These results suggest that OsPPT1a is a functional PPT involved in UQ biosynthesis in O. sativa.
Received January 20, 2006
Accepted February 20, 2006
Regular Paper
Functional Characterization of OsPPT1, Which Encodes p-hydroxybenzoate Polyprenyltransferase Involved in Ubiquinone Biosynthesis in Oryza sativa
Kazuaki Ohara 1,
Kyoko Yamamoto 1,
Masafumi Hamamoto 1,
Kanako Sasaki 1,
and
Kazufumi Yazaki 1 *
Kazufumi Yazaki, E-mail: yazaki{at}rish.kyoto-u.ac.jp
Abstract 
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  T. Akashi, K. Sasaki, T. Aoki, S.-i. Ayabe, and K. Yazaki Molecular Cloning and Characterization of a cDNA for Pterocarpan 4-Dimethylallyltransferase Catalyzing the Key Prenylation Step in the Biosynthesis of Glyceollin, a Soybean Phytoalexin Plant Physiology, February 1, 2009; 149(2): 683 - 693. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Ding, R. M. Williams, and D. H. Sherman Molecular Analysis of a 4-Dimethylallyltryptophan Synthase from Malbranchea aurantiaca J. Biol. Chem., June 6, 2008; 283(23): 16068 - 16076. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. Phillips, J. C. D'Auria, J. Gershenzon, and E. Pichersky The Arabidopsis thaliana Type I Isopentenyl Diphosphate Isomerases Are Targeted to Multiple Subcellular Compartments and Have Overlapping Functions in Isoprenoid Biosynthesis PLANT CELL, March 1, 2008; 20(3): 677 - 696. [Abstract] [Full Text] [PDF]
|
|