Phosphorylation mutants of p53 show differential complex formation with putative dehydrogenase Tms1 of fission yeast.
The yeast tms1 gene was originally identified as a multi-copy suppressor of a lethal growth arrest caused by expression of a tumour mutant cDNA of p53 in fission yeast. The tms1 gene product (Tms1) was found to form stable complexes with p53 in yeast and in vitro; using purified recombinant proteins, the interaction was mapped to the C-terminal region of p53. This part is known to be modified by several protein kinases resulting in a transition of p53 from a latent to an activated state capable of transactivating various cellular genes involved in growth suppression or apoptosis. Since there is evidence for an evolutionary conservation of a Tms1-related protein in mammals, the effect of the phosphorylation status of the C-terminus of p53 on Tms1/p53 complex formation in vitro has been investigated. Whereas mutants changing the cdc2 phosphorylation site at position 315 of human p53 had only little effect on Tms1/p53 complex formation, we found that mutants involving the protein kinase CK2 site at position 392 showed a significantly decreased relative affinity for the Tms1 protein. The same result was obtained by using a C-terminal fragment of p53 which was phosphorylated by purified protein kinase CK2, suggesting that the complex formation of p53 with cellular C-terminal binding proteins like Tms1 impairs regulation by phosphorylation.
Wagner
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Medical Biochemistry, University of Saarland, Homburg/Saar, Germany. bcpwag@krzsun.med-rz.uni-sb.de
D001665:Binding Sites; D047390:Casein Kinase II; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007064:L-Iditol 2-Dehydrogenase; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism*
D005656:Fungal Proteins; D011994:Recombinant Proteins; D029702:Schizosaccharomyces pombe Proteins; D016159:Tumor Suppressor Protein p53; D007064:L-Iditol 2-Dehydrogenase; C083985:TMS1 protein, S pombe; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases