Cool Video: How a Microtubule Builds and Deconstructs

A microtubule, part of the cell’s skeleton, builds and deconstructs. Credit: Eva Nogales lab, University of California, Berkeley.

In this animation, tubulin proteins snap into place like Lego blocks to build a microtubule, part of the cell’s skeleton. When construction ends, this long hollow cylinder falls to pieces from its top end. The breakdown is critical for many basic biological processes, including cell division, when rapidly shortening microtubules pull chromosomes into each daughter cell.

Until recently, scientists didn’t know exactly what drove microtubules to fall apart. A research team led by Eva Nogales of the Lawrence Berkeley National Laboratory and the University of California, Berkeley, now has an explanation.

Using high-powered microscopy, the scientists peered into the structure of a microtubule and found how a chemical reaction puts the stacking tubulin proteins under intense strain. The only thing keeping the proteins from springing apart is the pressure from the addition of more tubulin. So when assembly stops, the microtubule deconstructs.

The team also learned that Taxol, a common cancer drug, relieves this tension and allows microtubules to remain intact indefinitely. With microtubules frozen in place, a cancer cell cannot divide and eventually dies.

Because of this research, scientists now better understand both the success behind a common cancer drug and the molecular basis underlying the workings of microtubules.

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Bleach vs. Bacteria

Screenshot of the video showing how chlorine affects a bacterial protein
Exposure to hypochlorous acid causes bacterial proteins to unfold and stick to one another, leading to cell death. Credit: Video segment courtesy of the American Chemistry Council. View video

Spring cleaning often involves chlorine bleach, which has been used as a disinfectant for hundreds of years. But our bodies have been using bleach’s active component, hypochlorous acid, to help clean house for millennia. As part of our natural response to infection, certain types of immune cells produce hypochlorous acid to help kill invading microbes, including bacteria.

Researchers funded by the National Institutes of Health have made strides in understanding exactly how bleach kills bacteria—and how bacteria’s own defenses can protect against the cellular stress caused by bleach. The insights gained may lead to the development of new drugs to breach these microbial defenses, helping our bodies fight disease.

Continue reading this new Inside Life Science article.

Transporter Protein Dance Moves

Animation depicts the changes that allow a protein transporter to do its job.

In this video, Emad Tajkhorshid of the University of Illinois at Urbana-Champaign explains the molecular dance of transporter proteins, molecules that move substances across the cell membrane.

In this video, Emad Tajkhorshid of the University of Illinois at Urbana-Champaign explains the molecular dance of ABC transporters, a family of molecular machines that utilize ATP to move substances across the cell membrane. Tajkhorshid and his team recently used computational methods to map the movements between two known structural models of MsbA, a bacterial version of a transporter in human cells that helps to export anti-cancer drugs. They then described the individual steps of the molecular motions during the transport cycle. Understanding the process at such a detailed level could suggest new targets for treating a range of diseases, including some drug-resistant cancers that often make more transporter proteins to kick out medications meant to kill them.

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Cool Video: How Bee Venom Toxin Kills Cells

Credit: Huey Huang, Rice University.

Credit: Huey Huang, Rice University.

A new video, starring the toxin in bee venom, might help scientists design new drugs to combat bacterial infections. The video, by Rice University biophysicist Huey Huang Exit icon, condenses 6.5 minutes into less than a minute to show how the toxin, called melittin, destroys an animal or bacterial cell.

What looks like a red balloon is an artificial cell filled with red dye. Melittin molecules are colored green and float on the cell’s surface like twigs on a pond. As melittin accumulates on the cell’s membrane, the membrane expands to accommodate it. In the video, the membrane stretches into a column on the left.

When melittin levels reach a critical threshold, countless pinhole leaks burst open in the membrane. The cell’s vital fluids—red dye in the video—leak out through these pores. Within minutes, the cell collapses.

Many organisms use such a pore-forming technique to kill attacking bacterial cells. This research reveals molecular-level details of the strategy, bringing pharmaceutical scientists a step closer to harnessing it in the design of new antibiotics.

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