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Dr. Sanja Roje
.jpg) 509-335-3008
sanja@wsu.edu
Assistant
Professor, Institute of Biological Chemistry; Assistant Professor
of Molecular Plant Sciences. Ph.D. 1998, Florida State University.
Research
Research in
this laboratory deals with the metabolic engineering of folates
and methionine and riboflavin biosynthesis in plants. Folates are
the main cellular providers of one-carbon groups for metabolism
in most living organisms. Humans require folates in their diet but
are unable to synthesize these vitamins de novo. Folate deficiency
is common even in developed countries, and has been linked to anemia,
birth defects and vascular disease. Since plants are capable of
synthesizing folates de novo, and moreover represent the main dietary
source of folates in the human diet, metabolic engineering of plants
with increased folate content is an appealing choice for improving
folate uptake in human populations. Methionine (Met) is an essential
amino acid for humans and nonruminant animals. Crops used for animal
feed do not have optimal methionine content and must be fortified
with supplemental Met. The high cost of this supplementation has
prompted recent interest in metabolic engineering of plants with
increased Met content. The one-carbon metabolic network includes
reactions involving various folate species, and also provides methyl
groups for Met synthesis. This laboratory is currently testing the
concept that metabolic engineering of both folate and Met content
in plants can be achieved by taking advantage of subcellular compartmentation
of one-carbon reactions.
Riboflavin
(vitamin B2) is the precursor of the coenzymes flavin adenine dinucleotide
(FAD) and flavin mononucleotide (FMN). Deficiency of this vitamin
in humans has been linked to vascular disease, pregnancy complications,
and age-related cataracts. The long-term objective of this laboratory
is to provide means for improving riboflavin uptake in human populations
by engineering crops with increased riboflavin content. The microbial
enzymes (RibA-RibF) that catalyze the synthesis of riboflavin from
the precursors GTP and ribulose-5-phosphate, and its conversion
to FMN and FAD, have been cloned and biochemically characterized.
Homologs of RibA, RibB and RibE have been cloned from plants, indicating
that the plant riboflavin biosynthetic pathway probably uses the
same precursors as the microbial pathway, and consists of the same
or similar biochemical reactions. This laboratory currently focuses
on the elucidation of the riboflavin biosynthetic pathway in plants,
the mandatory first step before the engineering can be attempted.
Towards this goal, the laboratory is cloning and biochemically characterizing
plant enzymes involved in the biosynthesis of riboflavin and its
conversion to cofactors FMN and FAD, and investigating their subcellular
localization.
Selected
Publications
Cross, J.M., F.J. Sandoval, and S. Roje. 2007. An
HPLC-based fluorometric assay for cobalamin-independent methionine
synthase. Analytical Biochemistry 360(1):157-159.
Roje, S. 2006. S-Adenosyl-L-methionine: Beyond the universal
methyl group donor. Phytochemistry 67(15):1686-1698.
Sandoval, F.J., and Roje, S. An FMN hydrolase
is fused to a riboflavin kinase homolog in plants. Journal
of Biological Chemistry 280(46):38337-38345.
Goyer,
A., Illarionova, V., Roje, S., Fischer, M., Bacher, A. and Hanson,
A.D. 2004. Folate biosynthesis in higher plants. cDNA cloning,
heterologous expression, and characterization of dihydroneopterin
aldolases. Plant Physiol. 135:103-111.
Quinlivan,
E.P., Roje, S., Basset, G., Shachar-Hill, Y., Gregory, J.F., III
and Hanson, A.D. 2003. The folate precursor p-aminobenzoate
is reversibly converted to its glucose ester in the plant cytosol.
J. Biol. Chem. 278:20731-20737.
Roje,
S., Janave, M.T., Ziemak, M.J. and Hanson, A.D. 2002. Cloning and
characterization of mitochondrial 5-formyltetrahydrofolate cycloligase
from higher plants. J. Biol. Chem. 277:42748-42754. |
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