Characterization of salicylic acid‐responsive, Arabidopsis Dof domain proteins: overexpression of OBP3 leads to growth defects

• Published in: The Plant journal : for cell and molecular biology 2000-02, Vol.21 (4), p.329-339
• Main Authors: Kang, Hong‐Gu, Singh, Karam B.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - physiology; Arabidopsis Proteins; Arabidopsis thaliana; Base Sequence; Biological and medical sciences; cycloheximide; DNA Primers; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Dof protein; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; General aspects; Molecular Sequence Data; OBP1 protein; Phylogeny; Plant physiology and development; Reverse Transcriptase Polymerase Chain Reaction; salicylic acid; Sequence Alignment; Sequence Homology, Amino Acid; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Vegetative apparatus, growth and morphogenesis. Senescence; Zinc Fingers
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313x.2000.00678.x

Summary Dof proteins are unique to plants and contain a single zinc finger DNA‐binding domain called the Dof domain. OBP1, an Arabidopsis Dof protein, was previously isolated through an interaction with OBF4, an ocs element‐binding protein. Two additional Dof proteins, called OBP2 and OBP3, were isolated through homologous screening. All three OBP proteins contain transcriptional activation domains in their C‐terminal region. While no significant differences were found between the OBP proteins in terms of their DNA and protein‐binding properties, tissue‐specific RNA expression patterns were found. The RNA expression levels of all three OBP proteins increased following treatment with auxin, salicylic acid (SA) or cycloheximide, although the level of induction varied among the different proteins and in the tissues tested. These results suggest that even though they have similar DNA binding and protein–protein interaction properties, the different OBP proteins are likely to have distinct functions in specific parts of the plant. There is a good correlation between the expression of the OBP proteins and the ocs element, a stress‐response element which is also induced by auxin, SA and cycloheximide. To begin to analyze the function of the OBP proteins, transgenic lines overexpressing OBP3 were generated. These plants showed a severe growth defect with altered root development and yellowish leaves. The severity of the growth defects correlated with OBP3 expression levels and in some cases led to death, suggesting that some Dof proteins play important roles in plant growth and development.