Cis-acting elements essential for light regulation of the nuclear gene encoding the A subunit of chloroplast glyceraldehyde 3-phosphate dehydrogenase in Arabidopsis thaliana.

摘要

The characterization of the cis-acting elements involved in the light regulation of the nuclear gene (GapA) that encodes the A subunit of glyceraldehyde 3-phosphate dehydrogenase in Arabidopsis thaliana, is presented. Previous deletion analyses indicated that the -277 to -195 upstream region of GapA was essential for light induction of the beta-glucuronidase reporter gene in transgenic tobacco plants, and that this region contained 3 direct repeats with the consensus sequence 5'-CAAATGAA(A/G)A-3' (Gap boxes). Current results indicated that 2-bp substitutions of the last 4 nucleotides (AA or GA) of the Gap boxes by CC, abolished light induction of the beta-glucuronidase reporter gene in vivo and affected the binding of the Gap box binding factor invitro. Furthermore, an additional cis-acting element was identified (AE (Activation Element) box), which was involved in the regulation of GapA. A combination of a Gap box trimer and an AE box dimer conferred light responsiveness on the cauliflower mosaic virus 35S promoter containing the -92 to +6 upstream sequence, whereas oligomers of Gap boxes or AE boxes alone could not confer light responsiveness on the same promoter. It is suggested therefore that Gap boxes and AE boxes may function together asthe light-responsive element of GapA.