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The K domain mediates heterodimerization of the Arabidopsis floral organ identity proteins, APETALA3 and PISTILLATA
Author(s) -
Yang Yingzhen,
Fanning Laura,
Jack Thomas
Publication year - 2003
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.0960-7412.2003.01473.x
Subject(s) - arabidopsis , leucine zipper , mads box , mutant , bzip domain , biology , amino acid , gene , microbiology and biotechnology , genetics , peptide sequence
Summary MADS genes in plants encode key developmental regulators of vegetative and reproductive development. The majority of well‐characterized plant MADS proteins contain two conserved domains, the DNA‐binding MADS domain and the K domain. The K domain is predicted to form three amphipathic α‐helices referred to as K1, K2, and K3. In this report, we define amino acids and subdomains important for heterodimerization between the two Arabidopsis floral organ identity MADS proteins APETALA3 (AP3) and PISTILLATA (PI). Analysis of mutants defective in dimerization demonstrates that K1, K2 and the region between K1 and K2 are critical for the strength of AP3/PI dimerization. The majority of the critical amino acids are hydrophobic indicating that the K domain mediates AP3/PI interaction primarily through hydrophobic interactions. Specially, K1 of AP3 and PI resembles a leucine zipper motif. Most mutants defective in AP3/PI heterodimerization in yeast exhibit partial floral organ identity function in transgenic Arabidopsis . Our results also indicate that the motif containing Asn‐98 and specific charged residues in K1 (Glu‐97 in PI and Arg‐102 in AP3) are important for both the strength and specificity of AP3/PI heterodimer formation.