Isolation and characterization of four novel parsley proteins that interact with the transcriptional regulators CPRF1 and CPRF2

• Published in: Molecular genetics and genomics : MGG Vol. 265; no. 6; pp. 964 - 976
• Main Authors: Rügner, A, Frohnmeyer, H, Näke, C, Wellmer, F, Kircher, S, Schäfer, E, Harter, K
• Format: Journal Article
• Language: English
• Published: Germany Springer Nature B.V 01-08-2001
• Subjects: Amino Acid Sequence; Apiaceae; Apiaceae - genetics; Apiaceae - metabolism; Apiaceae - radiation effects; Basic-Leucine Zipper Transcription Factors; bZIP gene; Cells, Cultured; CIP gene; Cloning, Molecular; Conserved Sequence; CPRF1 protein; CPRF2 protein; CPRF5 protein; CPRF6 protein; CPRF7 protein; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; G-Box Binding Factors; Genes; Genomics; Leucine Zippers; Light; Localization; Molecular Sequence Data; Petroselinum crispum; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Proteins; Recombinant Proteins - metabolism; Repressor Proteins - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - growth & development; Sequence Alignment; Sequence Homology, Amino Acid; Transcription factors; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Ultraviolet Rays
• ISSN: 1617-4615; 1617-4623
• DOI: 10.1007/s004380100502

The common plant regulatory factors (CPRFs) from parsley are transcription factors with a basic-leucine-zipper motif that bind to cis-regulatory elements frequently found in promoters of light-regulated genes. Proposed to function in concert with members of other transcription factor families, CPRFs regulate the transcriptional activity of many target genes. Here, we report that, in contrast to CPRF2, which operates as a transcriptional activator, CPRF1 functions as repressor in vivo. Two-hybrid screens using CPRF1 and CPRF2 as "baits" resulted in the isolation of four novel parsley proteins which interact with either CPRF1 or CPRF2 in vivo. Three of these factors represent new parsley bZIP factors, designated CPRF5-CPRF7, whereas the fourth, named CPRF1-interacting protein (CIP), shows no homology to any other known protein. CPRF5 and CIP specifically interact with CPRF1, whilst CPRF6 and CPRF7 exclusively form heterodimers with CPRF2. CPRF5, CPRF6 and CPRF7 are transcription factors that exhibit sequence-specific DNA-binding as well as transactivation abilities, whereas the function of CIP remains elusive. The newly isolated CPRFs and CIP are constitutively localized in the nucleus in parsley protoplasts. Furthermore, mRNA accumulation studies revealed that the expression of these novel bZIP genes and CIP is not altered by exposure to light. We discuss the possible roles of the newly identified proteins in CPRF1- and CPRF2-dependent target gene expression.