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Researchers from the Universities of
Edinburgh, Goettingen, Tuebingen, and Strasbourg have discovered how a natural
antibiotic called dermcidin, produced by the skin when humans sweat, is a
highly efficient germ-fighting tool. The scientists uncovered the atomic
structure of the compound and were then able to determine what makes dermcidin
such an efficient weapon against dangerous germs.
When the skin is injured by a cut,
scratch, or insect sting, antibiotic agents secreted in sweat glands kill the
germs. These natural substances, called antimicrobial peptides, are more
effective than man-made antibiotics as germs are not able to quickly develop
resistance against them. They attack the weak point in the germs, their cell walls,
which cannot be changed quickly to resist the attack. Scientists already knew
that dermcidin was activated in salty, slightly acidic sweat. This sweat then
forms tiny channels perforating germs’ cell membranes, which are stabilized by
charged zinc particles in sweat. The water and charged particles flow
uncontrollably across the membrane, killing harmful bugs.
The researchers used a combination
of techniques to discover the atomic structure of the molecular channel and
found it to be unusually long, permeable, and adaptable, representing a new
class of membrane protein. The team found that dermcidin can adapt to widely
variable types of membrane. They believe this explains why dermcidin is such an
efficient broad-spectrum antibiotic and can fight off bacteria and fungi
simultaneously. Dermcidin is active against many well-known organisms such as
Mycobacterium tuberculosis and Staphylococcus aureus. The researchers hope that
this finding can contribute to developing a new class of antibiotics that can
kill some of these dangerous germs.
The full report, “Crystal Structure
and Functional Mechanism of a Human Antimicrobial Membrane Channel,” is
published online ahead of print in the journal Proceedings of the National
Academy of Sciences of the United States of America (February 20, 2013;
doi:10.1073/pnas.1214739110).
The Friends of AIDS Foundation is
dedicated to enhancing the quality of life for HIV positive individuals and
empowering people to make healthy choices to prevent the spread of the HIV
virus. To learn more about The Friends of AIDS Foundation, please visit: http://www.friendsofaids.org.
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