Arabidopsis SEPALLATA proteins differ in cooperative DNA-binding during the formation of floral quartet-like complexes. Issue 17 (2nd September 2014)

• Record Type: Journal Article
• Authors: Jetha, Khushboo; Theißen, Günter; Melzer, Rainer
• Is Part Of: Nucleic acids research. Volume 42:Issue 17(2014)
• Page Start: 10927
• Page End: 10942
• Publication Date: 2014-09-02
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gku755
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: The SEPALLATA ( SEP ) genes of Arabidopsis thaliana encode MADS-domain transcription factors that specify the identity of all floral organs. The four Arabidopsis SEP genes function in a largely yet not completely redundant manner. Here, we analysed interactions of the SEP proteins with DNA. All of the proteins were capable of forming tetrameric quartet-like complexes on DNA fragments carrying two sequence elements termed CArG-boxes. Distances between the CArG-boxes for strong cooperative DNA-binding were in the range of 4–6 helical turns. However, SEP1 also bound strongly to CArG-box pairs separated by smaller or larger distances, whereas SEP2 preferred large and SEP4 preferred small inter-site distances for binding. Cooperative binding of SEP3 was comparatively weak for most of the inter-site distances tested. All SEP proteins constituted floral quartet-like complexes together with the floral homeotic proteins APETALA3 (AP3) and PISTILLATA (PI) on the target genes AP3 and SEP3 . Our results suggest an important part of an explanation for why the different SEP proteins have largely, but not completely redundant functions in determining floral organ identity: they may bind to largely overlapping, but not identical sets of target genes that differ in the arrangement and spacing of the CArG-boxes in their cis -regulatory regions.