Bacterial
chemotaxis, the process by which a bacterium changes direction in response
to environmental
cues, involves a complex array of chemical receptors
(red, elongated
molecules) and other sensory proteins (blue and green molecules),
which work
together to process sensory information. A new study offers
high-resolution
details of the structure and function of the chemosensory array,
researchers
report. Image and video courtesy C. Keith Cassidy
(December 8, 2015) For
bacteria that swim, determining whether to stay the course or head in a new
direction is vital to survival. A new study offers atomic-level details of the
molecular machinery that allows swimming bacteria to sense their environment
and change direction when needed.
The study, reported in the journal eLife, represents a major
step in understanding the “bacterial brain,” said University of Illinois
physics professor Klaus Schulten, who led the new research.
“On its surface, a bacterium has thousands of receptors that
scan the environment and then tell it what to do,” he said. This is very much
like the sensory input that all animals must process. Of course, bacteria are
single-celled organisms and don’t have brains, he said. But they nonetheless
manage to organize and “remember” sensory signals long enough to respond to
them in a way that aids their own survival.
University of
Illinois physics professor Klaus Schulten, right; physics graduate student
Keith Cassidy,
center; postdoctoral researcher Juan Perilla and their colleagues used
experimental data
and computer simulations to determine the structure of key regions
of the “bacterial
brain.” Photo by L. Brian Stauffer
The receptors on the surface of a bacterial cell detect
light, chemicals, edible things and poisonous things, and transmit that
information to a deeper layer of proteins, called kinases, which interpret this
data and translate it into a simple choice: “Keep going” or “Change direction!”