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* Blanca Barquera
Blanca Barquera
Researchers Discover Mysterious Workings of Cholera Bacteria
An enzyme in the bacteria that causes cholera employs a previously unknown mechanism to generate energy, according to recent findings by a team of Rensselaer researchers. Because the enzyme is not found in most other organisms, including humans, the finding offers insights into how to defeat the bacteria without harming humans.

The team’s findings were published in Proceedings of the National Academy of Science.

Blanca Barquera, associate professor of biology, led the team (including research professor Joel Morgan and postdoctoral fellow Oscar Juarez) in studying Na+-NQR, an enzyme that is essentially two linked machines to create energy from food and electrically charge the cell membrane of Vibrio cholerae, powering many cellular functions.

Vibrio cholerae causes cholera, a disease transmitted primarily through contaminated drinking water. Cholera, which kills through dehydration caused by severe diarrhea and vomiting, is a major cause of death in the developing world, and in the aftermath of catastrophes that compromise water systems.
Barquera’s team found that the way in which the two machines are linked in Na+-NQR is different from other respiratory enzymes and likely involves much more movement of the protein than has been observed in other enzymes.

Their work stems from an interest in cellular respiration, whereby — in what amounts to a controlled burn — electrons are moved from food to oxygen. This process releases energy.

“Cellular respiration is remarkable,” Barquera said. “It is one of the most efficient energy conversion processes known, and does not require high temperatures. This efficiency has drawn the attention of researchers.”

In more complex organisms, like humans, the process of creating energy for a cell — respiration — takes place in specialized organelles within the cell called mitochondria. But in bacteria, which lack mitochondria, respiration occurs in the cell membrane. Na+-NQR is a respiratory enzyme found on the cell membrane of Vibrio Cholerae.

The enzyme creates energy through respiration and uses that energy to pump ions out of the cell, electrically charging the cell membrane and providing power for all the functions of the cell. Unlike similar enzymes found in many animals and bacteria, Na+-NQR pumps sodium ions out of the cell, rather than protons.

“It works in a very different way from enzymes in other bacteria and mitochondria. The catch and release of ions is done by movement of the protein,” Barquera said.

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Inside Rensselaer
Volume 4, Number 12, August 27, 2010
©2010 Rensselaer Polytechnic Institute
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