With grant support from the National Institutes of Health, the Frasch laboratory is examining the mechanism with which F₁ uses the hydrolysis of ATP to drive the rotation of the gamma subunit. In these studies, site-directed mutagenesis is used to change specific amino acid side chains in the protein. The enzyme that contains each mutant is then evaluated for differences in the ability to hydrolyze ATP and for the ATPase-dependent rotation of the gamma subunit as observed in single molecule experiments. The residues that are receiving the most intense scrutiny have some connection to those that serve as ligands to the magnesium cofactor of the enzyme. In previous work, the Frasch laboratory pioneered the combined use of EPR spectroscopy of vanadyl, a magnesium surrogate for F₁, with site-directed mutagenesis to identify how the metal ligands change with each step in catalysis. These ligand changes were shown to be essential to the sequential protein conformational changes in the catalytic mechanism.
Dr. Frasch’s laboratory has also used the F₁-ATPase as a biomolecular motor in the development of a Molecular Semaphore Device with funding from DARPA. This device uses the ability to detect the rotation of single F₁ molecules as a means to detect the hybridization of single molecules of DNA. The device has the potential to increase the sensitivity of detection of DNA microarrays to the ultimate single molecule level, and has received support from the defense department specifically to detect biological warfare agents like Anthrax. Drug testing and proteomics are additional potential applications of this device. The development of the single molecule technology for this device also has direct application to the basic research on the rotational mechanism of the F₁-ATPase in the Frasch laboratory.
Access to details about these projects is restricted, but will be moved to the public domain as each nears completion.