Biologists have long believed that cell membrane fission occurs after epsin molecules wedge themselves into the membrane’s surface, causing small pits that eventually bulge out and separate into new membrane structures.
But researchers at the University of Texas at Austin have discovered a previously unknown mechanism in the fission process that they’re calling protein crowding.
In a Wednesday minisymposium on membrane traffic control, doctoral candidate Wilton Snead explained that, rather than prying the membrane apart with its hydrophobic insertion, Epsin1 instead uses its helix like a grappling hook simply to stay in place.
Once enough epsin molecules crowd into the same area – regardless of whether every molecule has hooked into the membrane — surface pressure builds up and leads to spontaneous membrane fission.
What’s more, Snead said, size matters. Larger protein molecules mean more efficient fission, an observation in line with the idea that crowds of molecules – and not their wedges – cause fission.
The findings also help explain how early cells might have achieved fission before more complex protein machinery like dynamin evolved. “Any protein, regardless of its structure or assembly properties, can in principle drive fission,” Snead said. “A much greater variety of proteins may be involved in membrane fission than we thought.”
About the Author:
Janet Rae-Dupree is a Bay Area-based freelance writer covering science and innovation.
