Transactivation properties of parsley proline-rich bZIP transcription factors.
Light-responsive chalcone synthase (CHS) gene activation requires LRUCHS, a light regulatory promoter unit including the MYB recognition element MRECHS and the ACGT-containing element ACECHS. ACECHS is bound by the parsley basic region/leucine zipper (bZIP) factors CPRF1 and 4. Factors containing the bZIP domain exist in animals, plants and yeast, and recognize DNA sequence-specifically after formation of homo- or heterodimers. To determine the potential role of CPRFs in the regulation of CHS promoter activity, we investigated the functions of distinct CPRF domains in a homologous co-transfection system. The proline-rich domains of CPRF1 and CPRF4 activate transcription, indicating that CPRF1 and CPRF4 have transactivating properties. Over-expression of the CPRF1 bZIP domain caused a reduction of LRUCHS-mediated light inducibility, and point mutations throughout ACECHS affected both responsiveness to UV-containing white light and transactivation by CPRF1:VP16. The data suggest that a CPRF1-containing bZIP heterodimer interacts with ACECHS in vivo. We discuss regulatory steps in light-induced CHS transcription that may be influenced by CPRF1 and/or related bZIP factors.
Sprenger-Haussels
M
M
Max-Planck-Institut für Züchtungsforschung, Abteilung Biochemie, Carl-von-Linné-Weg 10, D-50829 Köln, Germany.
Weisshaar
B
B
D000217:Acyltransferases / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D019661:Apiaceae / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D016350:Leucine Zippers / Q000235:genetics; D008027:Light; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011392:Proline / Q000235:genetics; D011401:Promoter Regions, Genetic; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000528:radiation effects; D014162:Transfection
C069384:CPRF protein, Petroselinum crispum; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D015534:Trans-Activators; D011392:Proline; D000217:Acyltransferases; C020141:flavanone synthetase