Functional domains of the floral regulator AGAMOUS: characterization of the DNA binding domain and analysis of dominant negative mutations

Mizukami, Y., Huang, H., Tudor, M., Hu, Y., Ma, H. (1996) Functional domains of the floral regulator AGAMOUS: characterization of the DNA binding domain and analysis of dominant negative mutations. Plant Cell, 8 (5). pp. 831-45. ISSN 1040-4651 (Print)

URL: http://www.ncbi.nlm.nih.gov/pubmed/8672883
DOI: ​10.​1105/​tpc.​8.​5.​831

Abstract

The Arabidopsis MADS box gene AGAMOUS (AG) controls reproductive organ identity and floral meristem determinacy. The AG protein binds in vitro to DNA sequences similar to the targets of known MADS domain transcription factors. Whereas most plant MADS domain proteins begin with the MADS domain, AG and its orthologs contain a region N-terminal to the MADS domain. All plant MADS domain proteins share another region with moderate sequence similarity called the K domain. Neither the region (I region) that lies between the MADS and K domains nor the C-terminal region is conserved. We show here that the AG MADS domain and the I region are necessary and sufficient for DNA binding in vitro and that AG binds to DNA as a dimer. To investigate the in vivo function of the regions of AG not required for in vitro DNA binding, we introduced several AG constructs into wild-type plants and characterized their floral phenotypes. We show that transgenic Arabidopsis plants with a 35S-AG construct encoding an AG protein lacking the N-terminal region produced apetala 2 (ap2)-like flowers similar to those ectopically expressing AG proteins retaining the N-terminal region. This result suggests that the N-terminal region is not required to produce the ap2-like phenotype. In addition, transformants with a 35S-AG construct encoding an AG protein lacking the C-terminal region produced ag-like flowers, indicating that this truncated AG protein inhibits normal AG function. Finally, transformants with a 35S-AG construct encoding an AG protein lacking both K and C regions produced flowers with more stamens and carpels. The phenotypes of the AG transformants demonstrate that both the K domain and the C-terminal region have important and distinct in vivo functions. We discuss possible mechanisms through which AG may regulate downstream genes.

Item Type: Paper
Uncontrolled Keywords: Arabidopsis/genetics/ physiology Base Sequence Binding Sites DNA Primers DNA-Binding Proteins/biosynthesis/chemistry/ metabolism Genes, Dominant Genes, Plant MADS Domain Proteins Molecular Sequence Data Mutagenesis Mutagenesis, Site-Directed Plant Proteins Plants, Genetically Modified Polymerase Chain Reaction Recombinant Proteins/biosynthesis/chemistry/metabolism Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Sequence Deletion Transcription Factors/biosynthesis/chemistry/ metabolism
Subjects: organism description > plant > Arabidopsis
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > DNA binding protein
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > genes, structure and function > gene regulation
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > genes, structure and function > gene regulation

organism description > plant
CSHL Authors:
Communities: CSHL labs
Depositing User: Matt Covey
Date Deposited: 22 May 2014 16:38
Last Modified: 22 May 2014 16:38
PMCID: PMC161142
Related URLs:
URI: http://repository.cshl.edu/id/eprint/30153

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