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.
See:
Posted by Dr. Tim Sandle,
Pharmaceutical Microbiology
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Pharmaceutical Microbiology