CPRF4a, a novel plant bZIP protein of the CPRF family: comparative analyses of light-dependent expression, post-transcriptional regulation, nuclear import and heterodimerisation

Abstract

Several DNA-binding proteins with conserved basic region/leucine zipper domains (bZIP) have been isolated from parsley. They all recognise defined ACGT-containing elements (ACEs), including ACE(PcCHSII) in the Light Regulatory Unit LRU1 of the CHS promoter which confers light responsiveness. A new member of this Common Plant Regulatory Factor (CPRF) family, designated CPRF4a, has been cloned, which displays sequence similarity to HBP-1a from wheat, as well as to other plant bZIP proteins. CPRF4a specifically binds as a homodimer to ACE(PcCHSII) and forms heterodimers with CPRF1 but not with CPRF2. In adult parsley plants, CPRF2 and CPRF4a mRNAs are found in all tissues and organs in which the chalcone synthase gene CHS is expressed. In protoplasts from suspension cultured cells, UV irradiation (290-350 nm) did not cause an increase in levels of CPRF1, CPRF2, or CPRF4a mRNA, whereas the corresponding CPRF proteins accumulated within 15 min of light treatment. Furthermore, the rapid light-mediated increase of CPRF proteins was insensitive to transcriptional inhibitors, suggesting that a post-transcriptional mechanism controls CPRF accumulation. CPRFs as well as Arabidopsis thaliana G-box binding factors (GBFs) are selectively transported from the cytosol into the nucleus, as shown in an in vitro nuclear transport system prepared from evacuolated parsley protoplasts, indicating that cytosolic compounds are involved in regulated nuclear targeting of plant bZIP factors.

DNA Methylation Influences Chlorogenic Acid Biosynthesis in Lonicera japonica by Mediating LjbZIP8 to Regulate Phenylalanine Ammonia-Lyase 2 Expression

“…LjbZIP2 and LjbZIP3 were classified into subgroup H, while LjbZIP8 belongs to subgroup C. LjbZIP4 and LjbZIP9 were classified into subgroup F along with At4g35040 , At2g16770 , and At3g51960 . LjbZIP5 was classified into subgroup G, which includes GBF s from A. thaliana and their parsley homologs CPRF1 , CPRF3 , CPRF4a , and CPRF5 that are mainly linked to ultraviolet and blue-light signal transduction and the regulation of light-responsive promoters (Kircher et al, 1998). LjbZIP7 and LjbZIP11 were classified into subgroup A, which includes genes that play roles in ABA or stress signaling (Lescot et al, 2002).…”

Molecular events following perception of ultraviolet‐B radiation by plants

“…Four different proteins that bind to box 2 (or ACE CHS as the motif is also called), termed CPRF1, CPRF2, CPRF3, and CPRF4a (Common Plant Regulatory Factors), were found. They all belong to the basic region/leucine zipper domains (bZIP) class of DNA-binding proteins, and CPRF4a interacts with box 2 as a homodimer or as a heterodimer together with CPRF1 (Kircher et al 1998). UV radiation and blue light both cause a rapid increase in the levels of the CPRF1, CPRF2 and CPRF4a proteins.…”

“…UV radiation and blue light both cause a rapid increase in the levels of the CPRF1, CPRF2 and CPRF4a proteins. This rise in protein levels is independent of transcription (Kircher et al 1998). UV-B radiation also causes translocation of CPRF1 and CPRF2 from the cytosol into the nucleus in an in vitro assay (Kircher et al 1998).…”

“…This rise in protein levels is independent of transcription (Kircher et al 1998). UV-B radiation also causes translocation of CPRF1 and CPRF2 from the cytosol into the nucleus in an in vitro assay (Kircher et al 1998). This was suggested to occur after the CPRFs were phosphorylated .…”

Split‐plot microarray design allows sensitive detection of expression differences after ultraviolet radiation in the inbred parental lines of a key maize mapping population

“…These genes are transcriptional factors with a basic region for DNA binding followed by a leucine zipper region for dimerization. Binding sites for another class of bZIP factors, the CPRFs, are found in the promotor region of the UV-B-regulated parsley chalcone synthase gene; however, the CPRFs in parsley are regulated by protein phosphorylation rather than by alterations in transcription of their genes (Schafer, Kunkel & Frohnmeyer 1997;Kircher et al 1998). Thus, there are at least two different modes of ultraviolet radiation regulation of even this one structural class of transcription factors.…”