Phi Beta Kappa Society Visiting Scholars Program

"Microbial Hot Potato "

Professor Karen Fleming – Department of Biophysics, Johns Hopkins University

Although our existence appears deterministic, randomness underlies all molecular processes. We have explored this phenomenon using the quality control system engineered for outer membrane protein (OMP) biogenesis in bacteria. In the absence of any external energy, bacteria have an amazing ability to capture and directionally sort their OMPs to their proper cellular locations. Bacteria do this by essentially playing “hot potato” in which the client OMPs are passed around the periplasmic cellular compartment by a stochastic series of binding and release steps. Catch and toss steps are very quick, and the instantaneous bound lifetimes are short, much like the catch and toss of a hot potato. Computer modeling of this process explains how this biological network functions and highlights the integration of scientific disciplines ranging from microbial genetics to detailed biophysics.