| Abstract Detail
Mechanisms of Gene Regulation Stafstrom, Joel [1]. Expression of Arabidopsis Drg genes. Promoter::GUS fusions, quantitative RT-PCR and patterns of protein accumulation. DRGs are GTP binding proteins that are highly conserved but poorly understood at a functional level. All eukaryotes contain Drg1 and Drg2 orthologs. Arabidopsis has 3 Drg genes, AtDrg1 (At4g39520), AtDrg2 (At1g17420) and AtDrg3 (At1g72660). Drg2 and Drg3 encode proteins that are 95% identical, whereas AA identity between DRG1 and DRG2/3 is 55%. Patterns of mRNA and protein accumulation may point to aspects of gene/protein function. Microarray work done elsewhere indicates that Drg1 and Drg2 are expressed similarly in most tissues and under most conditions tested. Drg3 mRNA is absent in nearly all tissues, but is up-regulated by heat stress. We analyzed these genes using: 1) expression of promoter::GUS fusions in transgenic plants; 2) qRT-PCR to assess mRNA levels; and 3) Western blotting using DRG1- and DRG2-specific antibodies. Drg1 and Drg2 promoters show similar activity throughout seedlings, but roots, root apices and young root primordia have higher activity. Our qRT-PCR experiments indicate similar levels of Drg1 and Drg2 mRNA accumulation in most tissues. Drg3 mRNA was upregulated about 1000-fold after exposure to 37C for 3 hours. DRG1 antibodies recognize a 43kd band and DRG2 antibodies recognize 45, 43 and 30kd bands (the latter are breakdown products of 45kd). Plants were exposed to many environmental stresses (e.g., salt, heat, cold, uv light, osmotic) and examined by Western blotting. Relative few differences were seen. Heat stress gave rise to a protein of Mr 70kd that is recognized by DRG2 antibodies; this band disappeared during recovery. While this work suggests that DRG protein accumulation is constitutive, our other work shows that DRGs are present in the cytosol and associated with ribosomes, and can move between these compartments.
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1 - Northern Illinois University, Biological Sciences and Plant Molecular Biology Center, DeKalb, IL, 60115
Keywords:
GTP binding protein.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P36052
Abstract ID:2323 |
