Structural and functional characterization of the TgDRE multidomain protein, a DNA repair enzyme from Toxoplasma gondii.
The parasite Toxoplasma gondii expresses a 55 kDa protein or TgDRE that belongs to a novel family of proteins characterized by the presence of three domains, a human splicing factor 45-like motif (SF), a glycine-rich motif (G-patch), and a RNA recognition motif (RRM). The two latter domains are mainly known as RNA-binding domains, and their presence in TgDRE, whose partial DNA repair function was demonstrated, suggests that the protein could also be involved in the RNA metabolism. In this work, we characterized the structure and function of the different domains by using single or multidomain proteins to define their putative role. The SF45-like domain has a helical conformation and is involved in the oligomerization of the protein. The G-patch domain, mainly unstructured on its own as well as in the presence of the SF upstream and RRM downstream domains, is able to bind small RNA oligonucleotides. We also report the structure determination of the RRM domain from the NMR data. It adopts a classical betaalphabetabetaalphabeta topology consisting of a four-stranded beta sheet packed against two alpha helices but does not present the key residues for the RNA interaction. In contrast, our analysis shows that the RRM of TgDRE is not only unable to bind small RNA oligonucleotides but it also shares the protein-protein interaction characteristics with two unusual RRMs of the U2AF heterodimeric splicing factor. The presence of both RNA- and protein-binding domains seems to indicate that TgDRE could also be involved in RNA metabolism.
Frénal
Karine
K
Unité de Résonance Magnétique Nucléaire des Biomolécules, CNRS URA 2185, Institut Pasteur, 28 Rue du Docteur Roux, 75724 Paris Cedex 15, France.
Callebaut
Isabelle
I
Wecker
Karine
K
Prochnicka-Chalufour
Ada
A
Dendouga
Najoua
N
Zinn-Justin
Sophie
S
Delepierre
Muriel
M
Tomavo
Stanislas
S
Wolff
Nicolas
N
D000595:Amino Acid Sequence; D000818:Animals; D011088:DNA Ligases / Q000737:chemistry* / Q000378:metabolism*; D004795:Enzyme Stability; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000502:physiology; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D038621:Regulatory Sequences, Ribonucleic Acid; D016415:Sequence Alignment; D012995:Solubility; D013329:Structure-Activity Relationship
D015800:Protozoan Proteins; D011994:Recombinant Proteins; D038621:Regulatory Sequences, Ribonucleic Acid; D011088:DNA Ligases; C465218:DNA repair enzyme TgDRE, Toxoplasma gondii