Isolation of two soybean G‐box binding factors which interact with a G‐box sequence of an auxin‐responsive gene

• Published in: The Plant journal : for cell and molecular biology Vol. 8; no. 2; pp. 199 - 211
• Main Authors: Hong, Jong Chan, Cheong, Yong Hwa, Nagao, Ron T., Bahk, Jeong Dong, Key, Joe L., Cho, Moo Je
• Format: Journal Article
• Language: English
• Published: Osney Mead, Oxford OX2 0EL, UK Blackwell Science Ltd 01.08.1995; Blackwell Science
• Subjects: Amino Acid Sequence; Base Sequence; Basic-Leucine Zipper Transcription Factors; Biological and medical sciences; Blotting, Northern; Blotting, Southern; Cloning, Molecular; DNA, Complementary - genetics; DNA, Plant - genetics; DNA, Plant - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; G-Box Binding Factors; Gene Expression Regulation, Plant; Genes, Plant - genetics; Glycine max; Glycine max - genetics; Indoleacetic Acids - metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Multigene Family - genetics; Protein Binding; Protein Conformation; Regulatory Sequences, Nucleic Acid - genetics; Sequence Analysis, DNA; Transcription Factors; Transcription. Transcription factor. Splicing. Rna processing; Auxin; Nucleotide sequence; DNA binding protein; Homology; Molecular interaction; Gene expression; Glycine max; Leucine zipper structure; Leguminosae; Complementary DNA; Domain structure; Dicotyledones; Angiospermae; Regulatory sequence; Spermatophyta; Molecular complex; Transcription factor
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.1995.08020199.x

G‐box binding factors (GBFs) constitute a family of plant DNA‐binding proteins that bind to the G‐box motif, a regulatory cis element present in many plant genes with a palindromic DNA motif of CACGTG. Previously TCCACGTGTC, a G‐box motif, from an auxin responsive gene GmAux28 has been identified as a sequence‐specific protein‐binding site. Here the isolation of two soybean cDNA clones, referred to as SGBF‐1 and SGBF‐2, encoding proteins which bind to the G‐box motif is reported. The primary structure of SGBF‐1 and SGBF‐2 predicts that these proteins contain a basic leucine zipper (bZIP) DNA‐binding domain and an N‐terminal proline‐rich domain. A dramatic difference in the pattern of protein‐DNA complex formation was observed when recombinant SGBF‐1 and SGBF‐2 proteins were analyzed by electrophoretic mobility shift assays (EMSAs). The SGBF‐1 binding pattern obtained with the G‐box probe resulted in three major retarded bands while the SGBF‐2 formed a single complex. This shows that the characteristically diffuse banding pattern of plant nuclear proteins interacting with the G‐box is also observed in a binding assay using only one recombinant GBF. EMSAs were performed with a few selected binding sequences to study the effect of flanking nucleotides to the hexanucleotide G‐box core motif. The binding specificity of the SGBF proteins resembles that described for type A cauliflower nuclear G‐box binding proteins which bind class I G‐box elements [(G/T)(C/A)CACGTG(G/T)(A/C)]. Phylogenetic analysis of 13 GBF‐like proteins from various plant species reveals that the SGBF‐1 and SGBF‐2 proteins belong to different lineages, suggesting that they may have distinct functions in activating transcription.