DYNAMICS AND THERMODYNAMICS OF HUMAN CYTOMEGALOVIRUS PROTEINASE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Human herpesviruses are responsible for a wide range of diseases. Human cytomegalovirus (HCMV) may cause life-threatening infections especially for immunecompromised individuals (e.g. AIDS patients). HCMV encodes a protease necessary for the assembly of the viral capsid. Therefore, this enzyme is an ideal candidate for therapeutic intervention. The binding of inhibitors to the HCMV proteinase causes large conformational changes in the protein. In a complex process characterized as an induced-fit mechanism, conformational changes near the active site appear to be important in forming substrate binding pockets and perhaps in positioning the active site triad His-His-Ser. To get insight into this process, we propose to use NMR advanced spectroscopic methods to study the dynamics of the active site region in both the free protein and in the enzyme-inhibitor complex. These experiments will allow us to provide a detailed picture of the motions involved in the mechanism of induced-fit. We also propose to determine the pKa values of the active site residues in order to decipher the catalytic mechanism in this novel catalytic triad at atomic level. These data will provide valuable information towards the understanding of the mechanism of action of this enzyme and subsequent development of potent inhibitors of HCMV proteinase.