| Research Summary |
| All biochemical reactions require that macromolecules recognize each other within the cellular milieu upon receiving relevant cues or stimuli from their environment. In addition, they need to associate with affinities and kinetics suited to their function. These phenomena of recognition (specificity) and association (affinity, stability) and their correlation with function can be analyzed in an integrated fashion using structural and biochemical techniques. Our laboratory studies macromolecular interactions involved in the regulation of transcription and replication of the cancer-associated papillomaviruses. Using a combination of X-ray crystallography and quantitative biochemical assays we are probing the mechanisms by which the transcriptional regulatory protein E2 and the viral replication protein E1 recognize and discriminate between their DNA target sites on the viral genomes. We have determined the crystal structures of the DNA-binding domain of the E2 protein from the wart-causing strain BPV-1 and its complexes with several DNA target sequences, as well as that of the E2 protein from the high-risk cancer-associated strain HPV-16. E2 forms a dimeric beta-barrel and is the prototype for a novel structural class of DNA-binding proteins. DNA is wrapped around the protein barrel and numerous direct and solvent-mediated contacts between amino-acid side-chains and the exposed edges of bases in the major grooves of DNA contribute to the specificity of the interaction. In parallel biochemical experiments we have studied the effect of DNA deformability and nucleotide sequence-dependent conformation upon the affinity for E2, demonstrating that these evolutionarily-related proteins utilize distinct indirect readout mechanisms in recognizing their specific DNA binding-sites. In ongoing experimnets, we are extending our structural and biochemical characterization of papillomavirus proteins to include the interaction between the activation domain of the E2 protein with components of the basal transcription machinery, as well as the interaction between the E2 proteins and the replication protein E1. The overall goal of the research is to obtain a sterochemical and energetic analysis of vital molecular interactions in a model system of medical relevance.
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| Related Images |
Image 1 | The BPV-1 E2 protein is a dimeric beta-barrel. The DNA wraps around the protein enclosing its recognition helices in successive major grooves. |
| Research Information |
Research Interests | Structural Studies of Proteins involved in Transcription and DNA Replication | Research Keywords | cervical cancer, crystallographic studies, transcriptional regulation |
