Characterization of the promoter from the single-copy gene encoding ferredoxin-NADP⁺-oxidoreductase from spinach

Abstract

We describe a genomic DNA segment from spinach that bears part of the single-copy gene for ferredoxin-NADP⁺-oxidoreductase (FNR) including a 3.4 kb promoter sequence. Dissection of this DNA segment and its analysis in GUS (β -glucuronidase) gene fusions in transgenic tobacco demonstrated that the promoter differs in structure from all other promoters for thylakoid protein genes studied to date. Two regions with light-responsive elements were identified. One is located within the first 118 by upstream of the transcription initiation site. A second fragment covering nucleotide positions - 220 to - 119 is capable of conferring light-dependent GUS gene expression on two different minimal promoters. The latter fragment binds a trans-acting factor in gel-shift assays. None of the fragments carries cis elements known from other genes to be involved in light-controlled expression. Comparison of the light responsiveness of GUS gene fusions controlled by the -753/+231 and -118/+231 regions indicates that they respond differentially to phytochrome-dependent signals and that their expression in tobacco is not restricted to tissue with functional chloroplasts.