#bacterial toxin

[biology-geology-beaches-india]

The Scientific Research Notes of S. Sunkavally, Printed Part, page.128.

Dates unclear, but certainly between 2006-2012.

[medicomunicare]

Toxic platforms to hit cancer at the core: diphteria gives the example by breaking decay

Toxic platforms to hit cancer at the core: diphteria gives the example by breaking decay

A group of researchers from University of Toronto Engineering and SickKids Hospital have developed a new way to deliver molecules that target specific genes within cells. Their platform, which uses a modified form of a bacterial toxin, has been shown to downregulate critical genes in cancer cells, and could be used for other genetic diseases as well. The team, led by professors Molly Shoichet and…

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[biofixer-blog]

     Toxin for Self Protection : the case of Deadly Cholera Protein

Bacteria pull no punches when they fight to protect themselves. Some bacteria build toxins so powerful that a single molecule can kill an entire cell. This is far more effective than chemical poisons like cyanide or arsenic. Chemical poisons attack important molecules one by one, so many, many molecules of cyanide are needed to kill a cell. Bacterial toxins use two strategies to make their toxins far more deadly than this.

        The first strategy used to build super-deadly toxins is to use a targeting mechanism to deliver the toxin directly to the unlucky cell. Cholera toxin, ( shown as ribbon model on the second photo ), has a ring of five identical protein chains, colored blue here, which binds to carbohydrates on the surface of cells. This delivers the toxic part of the molecule, colored red, to the cell, where it can wreak its havoc.         The second deadly strategy is to use a toxic enzyme instead of a chemical poison. Enzymes are designed to perform their reactions over and over again, hopping from target to target and making their chemical changes. Thus, one enzyme can modify a whole cell full of molecules. Cholera uses this strategy once it gets inside cells. The toxic portion hops from molecule to molecule, disabling each one in turn, until the entire cell is killed.

         The catalytic portion of cholera toxin performs a single function: it seeks out the G proteins used for cellular signaling and attaches an ADP molecule to them (for more on G-proteins. This converts the G-protein into a permanently active state, so it sends a never-ending signal. This confuses the cell, and among other things, it begins to transport lots of water and sodium outwards. This floods the intestine, leading to life-threatening dehydration.

         "The two-part strategy employed by cholera toxin is highly effective, so much so that it is used by many different organisms that seek to protect themselves."

(Photo Credit: Prtotein Data Bank.)