Caption: Cyclic peptide (middle) binds to iPGM (blue). Credit: National Center for Advancing Translational Sciences, NIH
When you think of the causes of infectious diseases, what first comes to mind are probably viruses and bacteria. But parasites are another important source of devastating infection, especially in the developing world. Now, NIH researchers and their collaborators have discovered a new kind of treatment that holds promise for fighting parasitic roundworms. A bonus of this result is that this same treatment might work also for certain deadly kinds of bacteria.
The researchers identified the potential new therapeutic after testing more than a trillion small protein fragments, called cyclic peptides, to find one that could disable a vital enzyme in the disease-causing organisms, but leave similar enzymes in humans unscathed. Not only does this discovery raise hope for better treatments for many parasitic and bacterial diseases, it highlights the value of screening peptides in the search for ways to treat conditions that do not respond well—or have stopped responding—to more traditional chemical drug compounds.
Caption: Composite image of beta-galactosidase showing how cryo-EM’s resolution has improved dramatically in recent years. Older images to the left, more recent to the right. Credit: Veronica Falconieri, Subramaniam Lab, National Cancer Institute
In the quest to find faster, better ways of mapping the structure of proteins and other key biological molecules, a growing number of researchers are turning to an innovative method that pushes the idea of a freeze frame to a whole new level: cryo-electron microscopy (cryo-EM). The technique, which involves flash-freezing molecules in liquid nitrogen and bombarding them with electrons to capture their images with a special camera, has advanced dramatically since its inception thanks to the efforts of many creative minds. In fact, cryo-EM has improved so much that its mapping performance now rivals that of X-ray crystallography , the long-time workhorse of drug developers and structural biologists.
To get an idea of just how far cryo-EM has come over the last decade, take a look at the composite image above, which shows a bacterial enzyme (beta-galactosidase) bound to a drug-like molecule (phenylethyl beta-D-thiogalactopyranoside). To the left, you see a blob-like area generated by cryo-EM methods that would have been considered state-of-the-art just a few years ago. To the right, there’s an exquisitely detailed structure, which was produced at more than 10-times greater resolution using the latest advances in cryo-EM. In fact, today’s cryo-EM is so powerful that researchers can almost make out individual atoms! Very impressive, and just one of the many reasons why the journal Nature Methods recently named cryo-EM its “Method of the Year” for 2015 .
Today’s feature in my Cool Video series is a scientific film noir from the University of Florida in Gainesville. Channeling Humphrey Bogart’s hard-boiled approach to detective work, the protagonist of this video is tracking down metabolites—molecules involved in biological mysteries with more twists and turns than “The Maltese Falcon.”
If you’d like a few more details before or after watching the video, here’s how the scientists themselves describe their project: “Inside our cells, chemical heroes, victims, and villains leave behind clues about our health. Meet Dr. Art Edison, one of many metabolomics PIs who are on the case. Their quest? To tail and fingerprint small molecules, called metabolites, which result from the chemical processes that fuel and sustain life. Metabolites can shed light on the state of health, nutrition, or disease in a living thing—whether human, animal, or plant. Funded by National Institutes of Health grant U24DK097209, the University of Florida Southeast Center for Integrated Metabolomics is sleuthing through these cellular secrets.”
Caption: Healthy zebrafish (top) compared to zebrafish with arrhythmia-causing mutation (bottom). Their hearts are shown to the right, with enlargement indicating a weaker heart. The heart’s outflow tract is marked OFT; atrium, a; and ventricle, v. Credit: Asimaki et al. Science Translational Medicine
Arrhythmia is a condition in which the heart loses its regular rhythm, beating either too rapidly or too slowly. Occasional irregular heartbeats are harmless, but if sustained they can cause dizziness, fainting, and even sudden death. There are a number of drugs available that can prevent arrhythmias, but none are perfect. Implanted devices can help—pacemakers can keep the heart from beating too slowly, and defibrillators can reset the heart’s rhythm with an electrical shock if a dangerously rapid rhythm develops.
But new treatments are needed. Now, an NIH-funded research team has created an animal model that is advancing efforts to find new drugs to prevent arrhythmia. Led by Jeffrey Saffitz at Beth Israel Deaconess Medical Center, Boston, researchers used genetic engineering techniques to produce zebrafish with genetic mutations identical to those in some people who suffer from a rare inherited disease called arrhythmogenic cardiomyopathy (ACM). In humans, ACM leads to dangerous arrhythmias that can cause sudden cardiac death, usually in people under the age of 35.