We are determining the three-dimensional structures of several proteins associated with cancer. Certain strains of papillomavirus cause cutaneous warts, whereas several other strains are transmitted sexually and cause genital warts. Infections by roughly 50% of these strains are known to progress to cancer. Greater than 90% of cervical cancer tissue, for example, harbors papillomaviral DNA. One viral protein, the E2 protein, controls viral transcription and has an N-terminal transcriptional activation domain and a C-terminal DNA-binding domain. We are determining the structure for the DNA-binding domain from the human strain, HPV-16 and have collected the data necessary for NMR resonance assignment. A small molecular weight inhibitor for E2 from a different strain of virus (HPV-3 1) has been reported. We have repeated the structure activity relationship determination using the NMR method (SAR by NMR) for our HPV-16 E2 domain. We are also studying two peptides that interact with the E6 protein from the virus. The complex that one of these peptides makes (but not the other) promotes p53 degradation, which presumably leads to cellular proliferation. We hypothesize that since the peptides have similar amino acid sequences, they also have similar three-dimensional structures. The part from each of these peptides that interacts with E6 is observed to be alpha helical, with the amino acid residues most important for binding on one side of the structure. A third kind of protein we are studying is unrelated to papillomavirus, but is involved in many human cancers. The EH domain from RalBP1 is a protein in the Ras signaling pathway downstream from Ras. The EH domain binds calcium using a classical EF-hand motif and appears to interact with proteins associated with cellular sorting. The domain also binds peptides containing a """"""""NPF' motif and we are determining the structure of the EH domain by itself, and in complex with a NPF containing peptide. For the EH domain, we have collected the NMR data required for structure determination.
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