New Research Suggests Protein Crowding Plays an Important Role in Membrane Fission

Researchers from UT Austin’s Department of Biomedical Engineering have discovered a previously unknown mechanism of membrane fission—the process by which a cellular membrane splits into two distinct parts, facilitating important cellular functions like cell division, organelle formation, and vesicle trafficking.

Scientists have long held the idea that specific protein structures are required for shaping membranes and driving membrane traffic.

However, in a new paper published in Proceedings of the National Academy of Sciences (PNAS) and featured on the April 18, 2017 cover, findings from Assistant Professor Jeanne Stachowiak’s lab demonstrate that crowding among membrane-bound proteins provides a potent force for membrane fission, independent of protein structure. Like a compressed gas, proteins bump into each other and generate surface pressure sufficient to bend and break membranes. These findings could change how researchers think about disease treatment at the cellular level.

“It appears that the overall abundance and size of proteins on the membrane should influence drug or pathogen entry into the cell,” said Wilton Snead, a doctoral student in Stachowiak’s lab and the first author on the paper. “Our findings suggest that the physical effect of protein crowding could be used as a tool to enhance drug delivery or influence the presence of receptors at the plasma membrane.”

These findings also suggest how early cells, with little protein complexity, could have achieved membrane fission before the evolution of dedicated fission proteins.

protein crowding Wilton Snead

Pictured are bilayer membrane vesicles that have been exposed to ENTH, a protein involved in bending cellular membranes and driving membrane fission. This process helps break membranes into many smaller vesicles. Researchers found that when proteins bind membranes at high density, crowding amongst the proteins creates sufficient pressure at the membrane surface to drive fission. This general mechanism for membrane fission suggests that many more proteins may participate in this essential cellular process than previously believed. Picture courtesy of Wilton Snead and published in PNAS, April 18, 2017.