Lecture 6: Henry Lessen (Karen Fleming Lab)

Surprising results from a recent Beta-barrel membrane protein elasticity

OMPs have a common beta-barrel architecture. Image
from: Plummer, A. M., & Fleming, K. G. (2016). From
Chaperones to the Membrane with a BAM!. TiBS.

Outer membrane proteins (OMPs) play a central role in the integrity of the outer membrane of Gram-negative bacteria. The outermost membrane of Gram-negative bacteria is the ultimate protective barrier of the cell, serving as the first line of defense that guards against extracellular threats. Composed of both lipids and thousands of OMPs, biogenesis of outer membrane (OM) components and consequent OM integrity is essential for cell viability. Targeting these processes is a promising route for directed drug design against bacterial pathogens. Understanding of the OMP assembly machinery in bacteria has grown immensely owing to recent discoveries using several orthogonal techniques that include the publications of the crystal structures of key proteins recently.

OMPs have a common (beta-barrel) architecture, but they come in different sizes and functions (e.g. structural, adhesive, enzymatic and transport). OMPs are devoid of traditional cellular energy sources which point to the fact that the physical properties of the system are important. Lateral pressure applied onto the OMPs through the membrane is a key physics to study. Based on these observations, Henrey Lessen and his colleagues, using molecular dynamics simulations and an in-house developed biophysics model, obtain the elastic modulus and time-dependent forces acting on the barrel structure.

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Henry Lessen is from Alexandria, Louisiana. He completed his Bachelors of Science in Microbiology at Texas A&M University in College Station, TX where his undergraduate research was focused on improving the alkaline tolerance of cyanide degrading enzymes from yeast for possible use in bioremediation of metal-mining waste.

Currently, Henry is in Karen Fleming's lab in the Jenkins Department of Biophysics at Johns Hopkins University. His thesis research involves using experimental and computational methods to study the energetics of transmembrane backbone hydrogen bonds in the outer membrane proteins of gram-negative bacteria.