The evolutionarily conserved Dim1 protein defines a novel branch of the thioredoxin fold superfamily.

Zhang YZ, Gould KL, Dunbrack RL JR, Cheng H, Roder H, Golemis EA
Physiol Genomics. 1999 1 (3): 109-18

PMID: 11015569 · DOI:10.1152/physiolgenomics.1999.1.3.109

Dim1 is a small evolutionarily conserved protein essential for G2/M transition that has recently been implicated as a component of the mRNA splicing machinery. To date, the mechanism of Dim1 function remains poorly defined, in part because of the absence of informative sequence homologies between Dim1 and other functionally defined proteins or protein domains. We have used a combination of molecular modeling and NMR structural analysis to demonstrate that approximately 125 of the 142 amino acids of human Dim1 (hDim1) define a novel branch of the thioredoxin fold superfamily. Mutational analysis of Dim1 based on the predicted fold indicates that alterations in the region corresponding to the thioredoxin active site do not affect Dim1 activity. However, removal of a very short carboxy-terminal extension generates a dominant negative form of the protein [hDim1-(1-128)] that when overproduced induces cell cycle arrest in G2, via a mechanism likely to involve alteration of Dim1 association with partner molecules. In sum, this study identifies the Dim1 proteins as a novel sixth branch of the thioredoxin superfamily involved in cell cycle.

MeSH Terms (27)

Amino Acid Sequence Cell Cycle Cell Cycle Proteins Conserved Sequence DNA, Recombinant Evolution, Molecular Fungal Proteins G2 Phase Green Fluorescent Proteins HeLa Cells Humans Luminescent Proteins Magnetic Resonance Spectroscopy Microscopy, Fluorescence Molecular Sequence Data Mutation Plasmids Protein Folding Protein Structure, Secondary Recombinant Fusion Proteins Schizosaccharomyces Schizosaccharomyces pombe Proteins Sequence Alignment Sequence Homology, Amino Acid Thioredoxins Transfection Transformation, Genetic

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