Physical interactions between ABA response loci of Arabidopsis.
Genetic and physiological studies have shown that the Arabidopsis thaliana abscisic acid-insensitive (ABI) loci interact to regulate seed-specific and/or ABA-inducible gene expression. We have used the yeast two-hybrid assay to determine whether any of these genetic interactions reflect direct physical interactions. By this criterion, only ABI3 and ABI5 physically interact with each other, and ABI5 can form homodimers. The B1 domain of ABI3 is essential for this interaction; this is the first specific function ascribed to this domain of the ABI3/VP1 family. The ABI5 domains required for interaction with ABI3 include two conserved charged domains in the amino-terminal half of the protein. An additional conserved charged domain appears to have intrinsic transcription activation function in this assay. Yeast one-hybrid assays with a lacZ reporter gene under control of the late embryogenesis-abundant AtEm6 promoter show that only ABI5 binds directly to this promoter fragment.
Nakamura
S
S
Molecular, Cellular, and Developmental Biology Department, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.
Lynch
T J
TJ
Finkelstein
R R
RR
D000040:Abscisic Acid / Q000502:physiology*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D005786:Gene Expression Regulation / Q000502:physiology; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000378:metabolism; D020798:Two-Hybrid System Techniques
C409743:ABI5 protein, Arabidopsis; D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D014157:Transcription Factors; D000040:Abscisic Acid