Structure of zebrafish MO25

Abstract

MO25, a conserved scaffold protein, activates the tumour suppressor LKB1 with the pseudokinase STRAD. MO25 also promotes the activities of the STE20-family kinases MST3, MST4, STK25, SPAK and OSR1. Zebrafish MO25 was purified and crystallized, and a crystal of zebrafish MO25 diffracted to 2.9 Å resolution and belonged to space group P3221, with unit-cell parameters a = b = 156.665, c = 221.251 Å. The structure of zebrafish MO25 was determined by molecular replacement. It is constituted of seven helical repeats. Structural comparison indicates that the overall structures of zebrafish and human MO25 are very similar, suggesting that MO25 has conserved functions in zebrafish. This work provides a structural basis for further functional and evolutionary studies of MO25.

Keywords: MO25; scaffold proteins.

Figure 1

Sequence alignment of MO25 from different species, Homo sapiens (HUMAN), Danio rerio (DANRE; zebrafish), Drosophila melanogaster (DROME), Caenorhabditis elegans (CAEEL), Schizosaccharomyces pombe (SCHPO) and Arabidopsis thaliana (ARATH), was performed with ClustalW2 (Goujon et al., 2010; Larkin et al., 2007 ▶) and ESPript (Gouet et al., 1999 ▶). The secondary structure is shown according to the human MO25 structure. Identical residues among these species are highlighted with a red background, highly conserved residues are shown in red and all of these residues are boxed. Residues from MO25 involved in interaction with its partners are indicated with asterisks.

Figure 2

Elution profile of zebrafish MO25 from a HiLoad 16/60 Superdex 200 column. Inset, SDS–PAGE. Lane M contains molecular-mass markers (labelled in kDa).

Figure 3

Overall structure of zebrafish MO25 shown as cartoon (a, b) and surface (c, d) representations. Zebrafish MO25 is constituted of seven helical repeats. It forms a concave and a convex surface.

Figure 4

Structural comparison of zebrafish and human MO25. Zebrafish and human MO25 are coloured green and yellow, respectively. Their overall structures are very similar. The key residues from zebrafish and human MO25 involved in interactions with their partners are identical and are shown in stick representation.