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Cool Movie: Bacteria Working to Eat
Caption: Movie of the protein anchored in the inner membrane of bacteria tugs on a much larger protein in the outer membrane.
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Gram-negative bacteria perform molecular acrobatics just to eat. Because they're encased by two membranes, they must haul nutrients across both. To test one theory of how the bacteria manage this feat, researchers used computer simulations of two proteins involved in importing vitamin B12. Here, the protein (red) anchored in the inner membrane of bacteria tugs on a much larger protein (green and blue) in the outer membrane. Part of the larger protein unwinds, creating a pore through which the vitamin can pass. Courtesy of biophysicist Emad Tajkhorshid of University of Illinois at Urbana-Champaign.
Researchers aren't certain what causes autism, but studies of two protein families may offer a lead. To help nerve cells in the brain chat through synapses, two proteins—neuroligins and neurexins—partner to form a bridge across the synapse. Now, molecular pharmacologist Palmer Taylor of the University of California, San Diego, and colleagues have generated a structural model of this protein complex. The results offer a framework for understanding how changes in the proteins could impair synaptic connections. And, since mutations in the genes encoding neuroligins and neurexins are linked to autism, the findings could help explain this neurological disorder.
This work was also supported by NIH's National Institute of Environmental Health Sciences and National Institute of Diabetes and Digestive and Kidney Diseases.
Protein chemist Richard Roberts and his colleagues at the University of Southern California have extended the lives of fruit flies by blocking just a single receptor, a type of protein that transmits signals across the cell membrane. Using a method developed by Roberts, the team made short proteins, or peptides, and looked for the ones that could block a receptor involved in fruit fly aging. After finding protein-blocking peptides, the researchers genetically altered fruit flies to produce them. Those flies lived a third longer than normal. The approach could help researchers figure out how to block similar receptors involved in aging and disease.
Mouse with the FIG4 Charcot-Marie-Tooth disease mutation. Courtesy of Miriam Meisler. High
(51 KB JPEG)
Charcot-Marie-Tooth disease is a common inherited neurological disorder that often leads to pain and muscle weakness in the feet and legs. After three years of scientific sleuthing, geneticist Miriam Meisler of the University of Michigan has identified a previously unknown cause of the disease—a mutation in a gene called FIG4. Meisler's team discovered that a strain of laboratory mice with a wobbly gait had mutations in FIG4. Additional studies showed that a number of people with Charcot-Marie-Tooth disease also had this genetic change. The discovery could lead to a genetic test for one form of the condition and to new strategies for treating its symptoms.
This work was also supported by NIH's National Institute of Neurological Disorders and Stroke.
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