Multiple aromatic side chains within a disordered structure are critical for transcription and transforming activity of EWS family oncoproteins.
Chromosomal translocations involving the N-terminal approximately 250 residues of the Ewings sarcoma (EWS) oncogene produce a group of EWS fusion proteins (EFPs) that cause several distinct human cancers. EFPs are potent transcriptional activators and interact with other proteins required for mRNA biogenesis, indicating that EFPs induce tumorigenesis by perturbing gene expression. Although EFPs were discovered more than a decade ago, molecular analysis has been greatly hindered by the repetitive EWS activation domain (EAD) structure, containing multiple degenerate hexapeptide repeats (consensus SYGQQS) with a conserved tyrosine residue. By exploiting total gene synthesis, we have been able to systematically mutagenize the EAD and determine the effect on transcriptional activation by EWS/ATF1 and cellular transformation by EWS/Fli1. In both assays, we find the following requirements for EAD function. First, multiple tyrosine residues are essential. Second, phenylalanine can effectively substitute for tyrosine, showing that an aromatic ring can confer EAD function in the absence of tyrosine phosphorylation. Third, there is little requirement for specific peptide sequences and, thus, overall sequence composition (and not the degenerate hexapeptide repeat) confers EAD activity. Consistent with the above findings, we also report that the EAD is intrinsically disordered. However, a sensitive computational predictor of natural protein disorder (PONDR VL3) identifies potential molecular recognition features that are tyrosine-dependent and that correlate well with EAD function. In summary we have uncovered several molecular features of the EAD that will impact future studies of the broader EFP family and molecular recognition by complex intrinsically disordered proteins.
Ng
King Pan
KP
Department of Biology, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, S.A.R. China.
Potikyan
Gary
G
Savene
Rupert O V
RO
Denny
Christopher T
CT
Uversky
Vladimir N
VN
Lee
Kevin A W
KA
D024322:Amino Acids, Aromatic / Q000737:chemistry; D000818:Animals; D002471:Cell Transformation, Neoplastic; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D041681:NIH 3T3 Cells; D015514:Oncogene Proteins, Fusion / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D012512:Sarcoma, Ewing / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D024322:Amino Acids, Aromatic; C111598:EWS-ATF1 fusion protein, human; C106031:EWS-FLI fusion protein; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D034802:RNA-Binding Protein EWS; D011994:Recombinant Proteins; D014157:Transcription Factors