Poster: Posttranscriptional Regulation
Abs #
1081: Ferredoxin-1 mRNA stability and translation are two separable light regulatory processes conferred by the 5' UTR sequences.
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Presenter: |
Bhat, Sumana , sumana_bhat@hotmail.com |
Authors | Bhat, Sumana (A) Krueger, Angela (A) Tang, Li (A) Petracek, Marie E (A) | | Affiliations: |
(A): Oklahoma State University
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Light regulates translation and stability of pea Ferredoxin-1mRNA (Fed-1) in transgenic tobacco plants. To characterize the elements that control Fed-1 translation and mRNA stability, we fused segments of the transcribed portion of Fed-1 to other plant mRNA sequences (PetE,CP12 and EF-1a). From these analyses we found that light regulated translation of Fed-1 mRNA is controlled by redundant separable elements present within the 5' UTR, coding sequence and the 3' UTR. Using mutagenic analyses we are testing a hypothesis that a transient secondary structure of Fed-1 mRNA regulates translation. In contrast to the redundant translational control elements, light-regulated mRNA stability is only conferred by the 5' UTR of Fed-1 mRNA. The (CAUU)4 repeat present in the Fed-1 5' UTR is necessary for destabilizing the mRNA in dark. Substitution of single nucleotides within this repeat had dramatically different effects on mRNA accumulation. For example, mutation of (CAUU)4 to (CAUA)4 abolished the differential accumulation of Fed-1 mRNA, whereas mutation of the sequence to (AAUU)4 allowed light regulated mRNA accumulation. We are able to delete a Fed-1 5' UTR 33-nt putative stemloop, that is downstream of the (CAUU)4 and retain differential accumulation of the mRNA. However, the (CAUU)4 alone is not sufficient for differential mRNA accumulation when added to the 5' UTR of EF-1a mRNA. Thus additional deletion and mutagenesis experiments will be used to further define this element. With these results we are identifying proteins that differentially associate with Fed-1 5' UTR in the light and dark using UV-crosslinking assays.
