Binding of an endosperm-specific nuclear protein to a maize beta-zein gene correlates with zein transcriptional activity.
Promoter regions of alpha- and beta-zein genes were analyzed for binding of nuclear proteins from developing endosperm and seedling tissue of maize. Using a band-shift assay, we identified two distinct protein factors, alpha-1 and beta-1, that interacted specifically with alpha- and beta-zein gene promoter regions, respectively. Alpha-1 was present in nuclei from both endosperm and seedling tissue, whereas beta-1 was found only in nuclei from developing endosperm tissue. Mixing of nuclear extracts demonstrated that seedling tissue contained undetectable amounts of beta-1, rather than having an inhibitor for formation of the beta-1/DNA complex. Chemical footprinting analysis localized the beta-1 recognition site to a 22 bp sequence flanked by CCAT and TATA boxes. The apparent molecular mass of beta-1 was determined to be 29 kDa by southwestern blotting. Based on in vitro binding assays, the greatest concentration of the beta-1 in endosperm nuclei is at 16 days after pollination, which coincides with the time of highest transcriptional activity of the beta-zein gene. These results suggest that beta-1 may act as a tissue-specific, trans-acting regulator of the expression of the beta-zein gene in developing maize endosperm.
So
J S
JS
Department of Plant Sciences, University of Arizona, Tucson 85721.
Larkins
B A
BA
D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D015342:DNA Probes; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000378:metabolism*; D009841:Oligonucleotides / Q000138:chemical synthesis / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics* / Q000378:metabolism; D015028:Zein / Q000235:genetics*
D015342:DNA Probes; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D009841:Oligonucleotides; D004247:DNA; D015028:Zein