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Chemical Reaction: Talking Germs

By: Steve Herman
Posted: August 7, 2007, from the August 2007 issue of GCI Magazine.

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The V. harveyi attracted attention due to its bioluminescence. These bacteria have some basic chemistry similar to the firefly, discussed in a previous column4. The reaction involves luciferin catalyzed by luciferase with ATP as a cofactor. In different organisms, the genes and proteins involved in bioluminescence are unrelated. It may be confusing that the substrates and enzymes, though chemically different, are all referred to as luciferin and luciferase. To avoid confusion they should each be identified with the appropriate organism.

Into the Ocean’s Depths

Bioluminescence is common in the marine environment. It is most prevalent at mid-ocean depths, where it may occur in more than 95% of the individual organisms, and the light emission of luminous organisms exerts a significant influence on marine ecology. Bioluminescence is rare in the terrestrial environment, though firefly displays are among the most spectacular demonstrations of this process.

Autoinducers regulate mRNA production for specific genes in response to population density. Operons are a set of adjacent structural genes in bacteria whose mRNA is synthesized in one piece. V. harveyi have autoinducers LuxN and LuxQ, both transduced with the aid of LuxO through the relay protein LuxU5.

Okay, the details of Lux proteins are complicated and well left to specialists. The important point is that it involves proteins that send and receive signals. The signals are a call to action through the triggering of gene synthesis. Through this process, a single bacterium amazingly becomes part of a large group acting in unison. The news coming from Princeton is that this is pervasive in the bacterial world, not a rare phenomenon, and that it promises great opportunities for medical science.

Beyond Bacteria

There’s extensive knowledge of communication within and between cells beyond bacteria and bioluminescent organisms. If there is extensive damage to a cell’s DNA or it needs more collagen, researchers and scientists understand the signaling. Modern treatment cosmetics use these cellular communications to make efficacious products—at least in theory.