Poster: Regulation of gene expression

Abs # 767: Protein Kinase SNF1 Acts Upstream of A MYB Protein in the Sugar Signal Transduction Pathway in Plants

Presenter:	Yu, Su-May , sumay@imb.sinica.edu.tw
Authors	Lu, Chung-An  (A)   Lin, Tse-Cheng  (A)   Lee, Kuo-Wei  (A)   Ho, Shin-Lon  (A)   Huang, Li-Fen  (A)   Yu, Su-May  (A)
Affiliations:	(A): Inst of Molecular Biology, Academia Sinica, Taipei, Taiwan

The mechanism which connects sensing and transmission of sugar signal and the regulation of gene transcription in plants is largely unknown. The expression of α-amylase genes in cereals is suppressed by sugars and induced by sugar starvation. Previously, we identified a sugar response sequence (SRS) in the promoter of an α-amylase gene, αAmy3, and a MYB protein (OsMYBS) that interacts with SRS and activates αAmy3 promoter activity. In the present study, we isolated two rice genes encoding Snf1 kinases (OsSnf1). OsSnf1 is structurally and functionally conserved as the yeast homolog. Expression of OsSnf1 is also suppressed by sugars. Function of OsSnf1 was further studied by transient expression assays in rice embryos. Overexpression of OsSnf1 released sugar repression of SRS activity specifically through a cis-acting element, the TA box, in SRS that is known to interact with OsMYBS. OsSnf1 was shown to act upstream of OsMYBS in sugar derepression of SRS. For the first time, a component in the sugar signal transduction pathway is connected to a transcription factor for sugar regulation of gene expression in plants.