TY - JOUR
T1 - Biochemical characterization and crystal structure of a Dim1 family associated protein
T2 - Dim2
AU - Simeoni, Federica
AU - Arvai, Andy
AU - Bello, Paul
AU - Gondeau, Claire
AU - Hopfner, Karl Peter
AU - Neyroz, Paolo
AU - Heitz, Frederic
AU - Tainer, John
AU - Divita, Gilles
PY - 2005/9/13
Y1 - 2005/9/13
N2 - The U4/U6·U5 tri-snRNP complex is the catalytic core of the pre-mRNA splicing machinery. The thioredoxin-like protein hDim1 (U5-15 kDa) constitutes an essential component of the U5 particle, and its functions have been reported to be highly conserved throughout evolution. Recently, the Dim1-like protein (DLP) family has been extended to other proteins harboring similar sequence motifs. Here we report the biochemical characterization and crystallographic structure of a 149 amino acid protein, hDim2, which shares 38% sequence identity with hDim1. The crystallographic structure of hDim2 solved at 2.5 Å reveals a classical thioredoxin-fold structure. However, despite the similarity in the thioredoxin fold, hDim2 differs from hDim1 in many significant features. The structure of hDim2 contains an extra α helix (α3) and a β strand (β5), which stabilize the protein, suggesting that they may be involved in interactions with hDim2-specific partners. The stability and thermodynamic parameters of hDim2 were evaluated by combining circular dichroism and fluorescence spectroscopy together with chromatographic and cross-linking approaches. We have demonstrated that, in contrast to hDim1, hDim2 forms stable homodimers. The dimer interface is essentially stabilized by electrostatic interactions and involves tyrosine residues located in the α3 helix. Structural analysis reveals that hDim2 lacks some of the essential structural motifs and residues that are required for the biological activity and interactive properties of hDim1. Therefore, on the basis of structural investigations we suggest that, in higher eukaryotes, although both hDim1 and hDim2 are involved in pre-mRNA splicing, the two proteins are likely to participate in different multisubunit complexes and biological processes.
AB - The U4/U6·U5 tri-snRNP complex is the catalytic core of the pre-mRNA splicing machinery. The thioredoxin-like protein hDim1 (U5-15 kDa) constitutes an essential component of the U5 particle, and its functions have been reported to be highly conserved throughout evolution. Recently, the Dim1-like protein (DLP) family has been extended to other proteins harboring similar sequence motifs. Here we report the biochemical characterization and crystallographic structure of a 149 amino acid protein, hDim2, which shares 38% sequence identity with hDim1. The crystallographic structure of hDim2 solved at 2.5 Å reveals a classical thioredoxin-fold structure. However, despite the similarity in the thioredoxin fold, hDim2 differs from hDim1 in many significant features. The structure of hDim2 contains an extra α helix (α3) and a β strand (β5), which stabilize the protein, suggesting that they may be involved in interactions with hDim2-specific partners. The stability and thermodynamic parameters of hDim2 were evaluated by combining circular dichroism and fluorescence spectroscopy together with chromatographic and cross-linking approaches. We have demonstrated that, in contrast to hDim1, hDim2 forms stable homodimers. The dimer interface is essentially stabilized by electrostatic interactions and involves tyrosine residues located in the α3 helix. Structural analysis reveals that hDim2 lacks some of the essential structural motifs and residues that are required for the biological activity and interactive properties of hDim1. Therefore, on the basis of structural investigations we suggest that, in higher eukaryotes, although both hDim1 and hDim2 are involved in pre-mRNA splicing, the two proteins are likely to participate in different multisubunit complexes and biological processes.
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U2 - 10.1021/bi050427o
DO - 10.1021/bi050427o
M3 - Article
C2 - 16142897
AN - SCOPUS:24644464171
SN - 0006-2960
VL - 44
SP - 11997
EP - 12008
JO - Biochemistry
JF - Biochemistry
IS - 36
ER -