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Dr.
Howard D. Grimes
.jpg) 509-335-7723
grimes@wsu.edu
Dean
of the Graduate School. Ph.D. 1985, North Carolina State University.
Research
Our
laboratory is primarily interested in the biochemistry and regulation
of assimilate partitioning for both carbon and nitrogen. Within
this broad umbrella, we have projects specifically aimed at
1) metabolic engineering of sucrose metabolism, 2) identification
and characterization of sucrose transport proteins and protein-protein
interactions, 3) role of lipoxygenases as vegetative storage
proteins, and 4) biochemistry of lipoxygenase function in carbon
and nitrogen mobilization.
Central
to understanding carbon partitioning and its regulation is the
biochemical dissection of the individual transport steps along
this pathway. Sucrose uptake across the plasma membrane, long-distance
transport, and deposition into sink tissues offers several distinct
sites to address carbon flux management. Work focuses on the
integral, sucrose/H+ symporters (SUTs) at the plasma membrane
of plant cells. Site-directed mutagenesis and domain swapping
have been used to modify the transport properties of these proteins
and modification of the promoter elements allows control both
spatial and temporal aspects of gene expression. Hence, discrete
points in the carbon flux pathway can be altered in a highly
specific manner. Recently, we have identified a binding protein
associated with the cytosolic loop of the sucrose transporter.
Apparently this protein-protein interaction leads to the formation
of sucrose "metabolons" that
involve both plasma membrane transporters and cytoskeleton-linked
sucrose metabolizing enzymes.
The
reallocation of carbon and nitrogen from the vegetative organs
to the developing seeds is an especially important component
of plant productivity. Our laboratory discovered that a specific
lipoxygenase isoform functions as "vegetative storage protein" and
accumulates in the vacuole of a unique cell layer in leaves.
More recently we have shown that these plant vacuoles are able
to convert between lytic and storage functional states. This
latter discovery has propelled our research into the mechanistic
understanding of selective degradation of proteins in plant cells.
Selected
Publications
Youn, B., G.E. Sellhorn, R.J. Mirchel, B.J. Gaffney,
H.D. Grimes, and C. Kang. 2006. Crystal Structures of Vegetative
Soybean Lipoxygenase VLX-B and VLX-D, and Comparisons with Seed
Isoforms, LOX-1 and LOX-3. Proteins: structure, function,
and bioinformatics (in press).
Murphy, K.A., R.A. Kuhle, A.M. Fischer, A.A. Anterola,
and H.D. Grimes. 2005. The Functional Status of the Paraveinal
Mesophyll Vacuole Changes in Response to Altered Metabolic Conditions
in Soybean Leaves. Functional Plant Biology 32:335-344.
Elmer A.M., W.S. Chao, and H.D. Grimes. 2003. Protein Sorting and
Expression of a Unique Soybean Cotyledon Protein, GmSBP, Destined
for the Protein Storage Vacuole. Plant Molecular Biology. 52:1089-1106.
Aldape, M.J, A.M. Elmer, W.S. Chao, and H.D. Grimes. 2003. The
Identification and Characterization of a Sucrose Transporter Isolated
from the Developing Cotyledons of Soybean. Arch. Biochem. Biophys.
409:243-250.
Fisher, A.J., H.D. Grimes, and R. Fall. 2003. The
Biochemical Origin of Pentenol Emissions from Wounded Leaves.
Phytochem. 62:159-163.
Fuller, M., Weichert, H., Fischer, A., Feussner,
I., and H.D. Grimes. 2001. Activity of Soybean Lipoxygenase Isoforms
Against Esterified Fatty Acids Indicates Functional Specificity.
Arch. Biochem. Biophys. 388:146-154.
Dubbs, W.E. and H.D. Grimes. 2000. The Mid-PericarpCell
Layer in Soybean Pod Walls is a Multicellular Compartment Enriched
in Specific Lipoxygenase Isoforms. Plant Physiol. 123:1281-1288.
Dubbs, W.E. and H.D. Grimes. 2000. Specific Lipoxygenase
Isoforms Accumulate in Distinct Regions of Soybean Pod Walls and
Mark a Unique Cell Layer. Plant Physiol. 123:1269-1279.
Fischer, A.M., Dubbs, W.E., Baker, R.A., M.A. Fuller,
Stephenson, L.S., and H.D. Grimes. 1999. Protein Dynamics, Activity,
and Cellular Localization of Soybean Lipoxygenases Indicate Distinct
Functional Roles for Individual Isoforms. Plant Journal 19:543-554.
Jauh, G-Y., Fischer, A.M., Grimes, H.D., Ryan, C.A. and Rogers,
J.C. 1998. d-Tonoplast Intrinsic Protein Defines Unique Plant Vacuole
Functions. Proc. Natl. Acad. Sci. USA 95:12995-12999.
Stephenson, L.C., Bunker, T.W., Dubbs, W.E. and Grimes, H.D. 1998.
Differential Expression and Cellular Localization of Nitrogen-Responsive
Lipoxygenases in Soybean. Plant Physiology 116:923-933.
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