Thursday, 17 January 2019

Clearest view ever of cell membrane

Cell membranes are formed largely of a bimolecular sheet, a fraction of the thickness of a soap bubble, in which two layers of lipid molecules are packed with their hydrophobic tails pointing inward and their hydrophilic heads outward, exposed to water.

The internal shape and structure of this lipid bilayer have remained largely mysterious after almost a century of research. This is in large part because most methods to examine membranes use detergents, which strip away the lipids that make up much of the membranes' structures.

In a newly published paper in Proceedings of the National Academy of Sciences, the team -- led by Youzhong Guo, Ph.D., of VCU's School of Pharmacy -- used a new detergent-free method that allowed them to examine the membrane of an E. coli cell, with lipids still in place.

Where earlier models had shown a fluid, almost structureless lipid layer -- one often-cited research paper compared it to different weights of olive oil poured together -- the VCU-led team was startled to find a distinct hexagonal structure inside the membrane. This led the researchers to propose that the lipid layer might act as both sensor and energy transducer within a membrane-protein transporter.


Weihua Qiu, Ziao Fu, Guoyan G. Xu, Robert A. Grassucci, Yan Zhang, Joachim Frank, Wayne A. Hendrickson, Youzhong Guo. Structure and activity of lipid bilayer within a membrane-protein transporterProceedings of the National Academy of Sciences, 2018; 201812526 DOI: 10.1073/pnas.1812526115

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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