We are interested in establishing direct correlation between the biochemical states and the conformations of molecular machinery, while they are performing their tasks. Our main tools are cryo-electron microscopy (cryo-EM), which enables the structure determination of proteins near native conditions and optical spectroscopy, which has the ability to detect and characterize ligands on a single molecule level. In order to achieve our goals, we are developing strategies to combine the two techniques. We focus our efforts on several scientifically and medically important molecular machines and enzymes:
1. ABC exporters which translocate lipids, bile, and sterols across membranes and take part in multidrug resistance
2. Phospholipases that are modulated by bile
3. Membrane fusion machinery which enables cell-cell fusion and viral infection

1. Wagner J.M., Roganowicz M.D., Skorupka K., Alam S. L., Christensen D., Doss G., Wan Y., Frank G. A., Ganser-Pornillos B. K., Sundquist W. I., Pornillos O., "Mechanism of B-box 2 domain-mediated higher-order assembly of the retroviral restriction factor TRIM5α", eLife 5:e16309, (2016), doi: 10.7554/eLife.16309.

2. Frank G. A., Shukla S., Rao P., Borgnia M. J., Bartesaghi A, Merk A., Mobin A., Esser E., Gotessman M. M., Xia D., Ambudkar S. V., and Subramaniam S., "Cryo-EM analysis of the conformational landscape of human P-glycoprotein (ABCB1) during its catalytic cycle", Mol. Pharmacol. 90(1), (2016), doi: 10.1124/mol.116.104190.

3. Frank G. A., Narayan K., Bess J. W., Del Prete G. Q., Wu X., Moran A., Hartnell L. A., Earl L. A., Lifson D. J., and Subramaniam S., "Maturation of the HIV-1 core by a non-diffusional phase transition", Nature Communications 6:5854, (2015), doi: 10.1038/ncomms6854.

4. Tran E. E. H., Borgnia M. J., Kuybeda O., Schauder D. M., Bartesaghi A., Frank G. A., Sapiro G., Milne. J. L. S., Subramaniam S., "Structural mechanism of trimeric HIV-1 envelope glycoprotein activation", PLoS Pathog. 8(7): e1002797., (2012), doi: 10.1371/journal.ppat.1002797.

5. Frank G. A., Bartesaghi A., Kuybeda O., Borgnia M. J., White T. A., Sapiro G., Subramaniam S., "Computational separation of conformational heterogeneity using cryo-electron tomography and 3D sub-volume averaging", J. Struct. Biol. 178(2), (2012), doi: 10.1016/j.jsb.2012.01.004.