Structural Biology and Protein Biophysics

Our research program seeks to understand, in molecular detail, fundamental cellular processes that occur at the membrane interface. We utilize a multidisciplinary approach, emphasizing in vitro assays to test fundemental aspects of membrane protein folding and insertion. The core projects in our lab are:

(i) Folding and Insertion of Membrane Proteins in the Bacterial and Mitochondrial Outer Membrane

 We seek to understand the molecular mechanisms by which chaperones and the BAM membrane protein complex cooperate to  promote folding and specific insertion of β-barrel OMPs into bacterial and mitochondrial outer membranes. Of particular interest is whether BAM utilizes lateral gating to directly pass nascent OMPs into the membrane. By locking the seam of BamA in both in vitro and in vivo assays, we can directly assess the effect of seam flexibility and gain a better understanding of how this essential complex works. 

(ii) AFM Based Single Molecule Force Spectroscopy 

In collaboration with the Perkins lab, we seek to directly measure protein folding and unfolding using atomic force microscopy (AFM). specifically attaching to both the AFM surface and tip, we drastically increase our data throughput, allowing us to rapidly characterize their response to force. Of current interest is NleC,  a zincin protease which is secreted by the Type III Secretion System (T3SS). In order to be secreted, it must pass through the narrow, needle-like structure of the T3SS, requiring at least partial unfolding. We're exploring which aspects of NleC are allow it to be secreted but rapidly refold once inside the host cell. A secondary AFM project aims measure the unfolding and refolding of outer membrane proteins from the membrane, elucidating whether or not these proteins can be inserted haripin by hairpin without the assitance of BamA.