Crystallization studies of the keratin-like domain from Arabidopsis thaliana SEPALLATA 3

Abstract

In higher plants, the MADS-box genes encode a large family of transcription factors (TFs) involved in key developmental processes, most notably plant reproduction, flowering and floral organ development. SEPALLATA 3 (SEP3) is a member of the MADS TF family and plays a role in the development of the floral organs through the formation of multiprotein complexes with other MADS-family TFs. SEP3 is divided into four domains: the M (MADS) domain, involved in DNA binding and dimerization, the I (intervening) domain, a short domain involved in dimerization, the K (keratin-like) domain important for multimeric MADS complex formation and the C (C-terminal) domain, a largely unstructured region putatively important for higher-order complex formation. The entire K domain along with a portion of the I and C domains of SEP3 was crystallized using high-throughput robotic screening followed by optimization. The crystals belonged to space group P2(1)2(1)2, with unit-cell parameters a = 123.44, b = 143.07, c = 49.83 Å, and a complete data set was collected to 2.53 Å resolution.

Keywords: Arabidopsis thaliana; MADS-box; SEPALLATA 3; keratin-like domain; transcription factors.

Figure 1

Sequence of SEPALLATA 3 with the predicted secondary structure. Helices are shown in red, β-strands in blue and loops in black. The protein is colour-coded by domain with M in green, I in yellow, K in blue and C in purple.

Figure 2

Crystals of SEP3_74–175. The crystals were grown from 0.1 M Tris pH 8.0, 25% ethylene glycol.