The <Emphasis Type="Italic">pds2</Emphasis> mutation is a lesion in the <Emphasis Type="Italic">Arabidopsis</Emphasis> homogentisate solanesyltransferase gene involved in plastoquinone biosynthesis |
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Authors: | Li Tian Dean DellaPenna Richard A Dixon |
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Institution: | (1) Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401, USA;(2) Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA |
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Abstract: | Plastoquinone plays critical roles in photosynthesis, chlororespiration and carotenoid biosynthesis. The previously isolated
pds2 mutant from Arabidopsis was deficient in tocopherol and plastoquinone accumulation, and the biochemical phenotype of this mutant could not be reversed
by externally applied homogentisate, suggesting a later step in tocopherol and/or plastoquinone biosynthesis had been disrupted.
Recently, the protein encoded by At3g11950 (AtHST) was shown to condense homogentisate with solanesyl diphosphate (SDP), the substrate for plastoquinone synthesis, but not
phytyl diphosphate (PDP), the substrate for tocopherol biosynthesis. We have sequenced the AtHST allele in the pds2 mutant background and identified an in-frame 6 bp (2 aa) deletion in the gene. The pds2 mutation could be functionally complemented by constitutive expression of AtHST, demonstrating that the molecular basis for the pds2 mutation is this 6 bp-lesion in the AtHST gene. Confocal microscopy of EGFP tagged AtHST suggested that AtHST is localized to the chloroplast envelope, supporting
the hypothesis that plastoquinone synthesis occurs in the plastid. |
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Keywords: | Homogentisate pds2 Plastoquinone Prenyltransferase Solanesyl diphosphate |
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