Advancing mechanistic understanding at membrane interfaces

The National Institute of General Medical Sciences awarded the University of Missouri System $418,822 on April 5, 2026, under the Biomedical Research and Research Training program (CFDA 93.859) to advance mechanistic understanding of membrane interfaces.

The research addresses two primary areas: understanding the mechanism by which candidalysin, a peptide virulence factor secreted by Candida albicans, attacks host cell membranes by forming pores in lipid bilayers; and defining the mechanism of protein translocation across membranes through the general secretory (SEC) system in Escherichia coli, particularly the conformational changes that the translocon SecYEG and peripheral ATPase SecA undergo during protein export. The work will employ direct imaging techniques to elucidate precursor-dependent translocase conformations and expand understanding of protein transportation modes across membranes.

The award supports research at the University of Missouri in Columbia, Missouri, with a period of performance extending through February 28, 2031. The University of Missouri System, a state-controlled comprehensive public research institution and 1862 Land Grant College, serves as the recipient. This is a Project Grant, the assistance type used by NIGMS for investigator-initiated research.

Abstract

Membranes are central to life. These vital biological structures define cellular perimeters, control intercellular fluxes, and enable intracellular compartmentalization. Despite fundamental and pharmaceutical importance many gaps exist in our knowledge of membranes and in their diverse activities. This research project addresses shortcomings of knowledge in two key areas: we seek to (i) understand the mechanism of host cell membrane attack by candidalysin (CL), the recently discovered peptide virulence factor of candida albicans, and to (II) define the mechanism of protein translocation across membranes in the general secretory (SEC) system of escherichia coli. The first focus area centers on the yeast c. Albicans, which infects human cells by releasing CL. We recently showed that the CL toxin readily self-assembles into polymers in solution which then create pores in lipid bilayers. However, knowledge in this area is incipient and many critical questions remain open. We seek to determine the formation mechanism of CL pores and understand the physiological factors that control the extent of membrane damage that CL inflicts. The second area of research centers on understanding protein export through the translocon, secyeg. This heterotrimeric transmembrane complex is homologous to eukaryotic SEC61. Though the translocation mechanism is understood only superficially, IT is certain that the macromolecules involved, including peripheral atpase seca, undergo large conformational changes and do so in a highly coordinated fashion. Our direct imaging of the SEC system at work in close-to-native conditions revealed precursor-dependent translocase conformations, challenging conventional models which assume a single transportation mechanism for all precursors. We seek to expand upon these results and define the mode(s) of protein transportation across the membrane. A variety of techniques will be deployed to address these gaps in understanding including single molecule atomic force microscopy (AFM), electron microscopy, mutagenesis, and neutron reflectometry. The biophysical analyses will be pushed further towards in vivo conditions. Results will be verified biologically. This research will provide new insights into mechanisms underlying a key fungal virulence factor and a ubiquitous protein translocation apparatus. The information garnered is expected to accelerate the development of novel therapeutics.