A maize zinc-finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2.
The prolamin box (P-box) is a highly conserved 7-bp sequence element (5'-TGTAAAG-3') found in the promoters of many cereal seed storage protein genes. Nuclear factors from maize endosperm specifically interact with the P-box present in maize prolamin genes (zeins). The presence of the P-box in all zein gene promoters suggests that interactions between endosperm DNA binding proteins and the P-box may play an important role in the coordinate activation of zein gene expression during endosperm development. We have cloned an endosperm-specific maize cDNA, named prolamin-box binding factor (PBF), that encodes a member of the recently described Dof class of plant Cys2-Cys2 zinc-finger DNA binding proteins. When tested in gel shift assays, PBF exhibits the same sequence-specific binding to the P-box as factors present in maize endosperm nuclei. Additionally, PBF interacts in vitro with the basic leucine zipper protein Opaque2, a known transcriptional activator of zein gene expression whose target site lies 20 bp downstream of the P-box in the 22-kDa zein gene promoter. The isolation of the PBF gene provides an essential tool to further investigate the functional role of the highly conserved P-box in regulating cereal storage protein gene expression.
Vicente-Carbajosa
J
J
Department of Biology, University of California at San Diego, Mail Code 0116, La Jolla, CA 92093, USA.
Moose
S P
SP
Parsons
R L
RL
Schmidt
R J
RJ
D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D003313:Zea mays / Q000235:genetics*; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014157:Transcription Factors; C067402:opaque-2 protein, Zea mays