Bacillus anthracis is a gram positive rod bacteria which can cause a serious, and more often than not, lethal disease known simply as anthrax. Anthrax received a substantial amount of attention in 2001, when it was feared the bacteria would be used as a form of biological warfare. The situation was resolved, but not before 5 people were declared dead and another 17 injured in the space of several weeks. This led to an increase in the study of Bacillus anthracis, and although multiple discoveries have been made concerning methods of infection, there are still more questions to be answered.
Bacillus anthracis is highly virulent, a factor that can be largely attributed to its ability to form endospores, and its secretion of a substance known as anthrax toxin. Endospores are non-reproductive structures that are highly resistant to most processes that could kill a cell, such as extreme heat or radiation, and they form under circumstances of starvation as a way of preserving the toxin. Anthrax toxin itself is made of three components which are only lethal when combined. The three toxins are protective antigen, lethal factor, and edema factor; hereafter referred to as PA, LF, and EF respectively. LF is a Zn²⁺ dependent protease, and EF is a calmodulin-dependent adenylyl cyclase. 1
As a general summary, the anthrax toxin infects the host cell by creating a pore in the plasma membrane and causing the cell to intake LF/EF via receptor mediated endocytosis. LF and EF then create another pore to leave the endosome before it gets to its destination, releasing it into the cytosol before it is properly detected.
This infection begins as PA binds to surface receptors on the target host cell. It is necessary for infection for multiple PA toxin...
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...membrane, simulating the gradient across the endosomal membrane, such that the cis compartment is acidic and the trans compartment neutral, acidic side chains approaching the barrier from the cis direction will have a higher probability of being protonated and diffusing past the barrier. Thus thermal fluctuations of the polypeptide chain will be biased in the cis-to-trans direction, causing...a net translocation in that direction. Also, protons that become associated with acidic side chains in the cis compartment are released into the trans compartment, making the PA pore formally a protein–proton symporter
This mechanism for the active transport of LF and EF across the endosomal membrane is well supported, but is still under scrutiny.
Another largely unknown mechanism is how the two toxins are refolded once in the cytoplasm, and what they actually do from there.
Also contributing to the virulence of the bacteria are the exotoxins including invasive adenylate cyclase, tracheal cytotoxin, and lethal toxin. Invasive adenylate cyclase reduces local phagocytic activity as well as acting as a hemolysin. Tracheal toxin affects the ciliated respiratory epithelium by inhibiting the ciliary beating. This kills the cells and causes them to be eliminated from the mucosa. Tracheal toxin also stimulates the release of IL-1, which causes fever. Lastly, lethal toxin causes inflammation and local necrosis at infection sites.
Dr. Akabas ended his paper with a summary of his results. He concluded that Gly-91, Lys-95, and Gln-98 all line the CFTR channel and are arranged in a helical formation. Dr. Akabas also talked about the problems and surprises he faced during his experiment, such as a missense mutation of Gly-91 to Arg. In the end, substituted-cysteine-accessibility method exceeded the expectations of many and contributed greatly to our knowledge of the CFTR channel. Even though more research and discovery is being done today, we will always remember Dr. Akabas’s experiment as being the basis of the CFTR science.
Some strains of this microorganism produce C. perfringens enterotoxin (CPE), a group of toxins that cause a variety of adverse effects in the host. Strains of C. perfringens are classified as 5 biotypes, A – E, depending on the production of four major enterotoxins (α, β, ε and ι). In addition, strains of C. perfringens may also produce a number of other toxins including neuraminidase, hyaluronidase, and collagenase. For example, α-toxin, produced by C. perfringens type A, is primarily responsible for the production of gas gangrene. However, only roughly 5% of C. perfringens carry the CPE gene that codes for the production of these toxins. CPE is inactivated at 74oC.
The 2001 anthrax attacks was one of the worst bio-weapon attacks on the US in history. The attacks where done through the mail. The anthrax was placed in envelopes with a letter and mailed from various locations to different people and organizations. The anthrax filled letters ended up killing 5 people, causing 17 to become sick and exposing anthrax it is believed to as many as 30,000 people. During the mail process spores of anthrax from the letters escaped and got on mailroom equipment exposing postal employees. If a person was exposed to enough anthrax and developed symptoms they typically died in a few days. Postal workers during the attacks where told that anthrax will appear as a white powder t...
Kopp, Elizabeth, and Medzhitov, Ruslan. “A Plague on Host Defense.” The Journal of Experimental Medicine. .
Linkous, J. (2004). More details on new anthrax search. Retrieved Oct. 06, 2005, from CBS News Web site: http://www.cbsnews.com/stories/2004/10/05/national/main647441.shtml.
e. If saxtoxin is such a powerful toxin in people who eat contaminated shellfish, why does the toxin not poison/kill the host shellfish?
Extra credit 1). Propose an experiment to test the importance of this property for transmembrane protein insertion and orientation. Up to 2.5 pts¬¬
Membranes play an integral function in trapping and securing metabolic products within the borders of a cell within an aqueous environment. Without a selectively permeable border surrounding sites of anabolic function, potential useful products of this metabolism would simply diffuse away in the aqueous environment contained within and surrounding the cell. However, securing metabolites within the cell also comes with a price of not being able to acquire potentially useful compounds from the surrounding environment. Some very small gases and polar uncharged compounds are able to simply diffuse across this membrane, moving to the site of lower concentration on either side of the membrane. However, larger uncharged and charged polar molecules,
Anthrax is a very contagious, soil-borne disease. It is caused by Bacillus anthracis. Anthrax is a disease that is very common in herbivores which is why cattle and bison are so susceptible to it. Anthrax infections are very rare in humans. Anthrax is susceptible to most antibiotics, so treatment of animals at early signs of the disease should be effective. Treatment with antibiotics, such as Anthrax Spore Vaccine will counteract the vaccine, so should not be administered to animals who have been recently
Botulinum toxin is the toxin produced by the bacteria Clostridium botulinum. (CDC) This toxin is the most poisonous substance known to man. (Reddy) One gram of botulinum, if distributed evenly, could kill one million people if inhaled. (Reddy) Botulism, the disease caused by botulinum toxin, is very rare; there are only roughly 145 new cases in the United States each year. (CDC) However, even though the toxin is so poisonous, it’s also used in a common everyday item: Botox. (National)
Anthrax has been around for thousands of years. According to the Centers for Disease Control and Prevention (CDC), anthrax is believed to have originated in Egypt and Mesopotamia in the late 1300s B.C.E. during the time of the 10 plagues. Many believe it was the fifth plague. Ancient Greece and Rome also discovered anthrax, as the famous author Homer referenced it in The Iliad around 700 B.C. (https://www.cdc.gov/anthrax/resources/history/index.html). For many years, anthrax was studied in detail. Robert Koch was the first person to note the life cycle of the disease, and in 1881, the first vaccine for animals was created (https://www.cdc.gov/anthrax/resources/history/index.html). Anthrax is mostly found in animals such as ovine, bovine, equine, etc. It is a zoonotic disease meaning, it can be transferred from animal to human. People began to contract anthrax from meat consumption, specifically meat from cattle. As the animal vaccine became more popular, it was noted that the vaccine helped to lower the number of reported human anthrax
Louis Pasteur, in 1881, discovered the anthrax vaccine. Anthrax is an infection caused by many bacteria cells called “Bacillus”. These bacteria make “spores” which have a protective shell. This disease is most common in farm animals. They live in soil, and affect domestic a...
The first and best known example is the various sub-species of the bacterium ‘Bacillus thurnigenesis’. As mentioned earlier, these produce crystalline proteins otherwise known as ‘Δ-endotoxins’ or ‘cry proteins’ (Ellis et al, 2002). These endotoxins attack the digestive tract of the insect. The Bt spores then leaks from the gut and germinate in the insect causing death within few days. Bacillus thurnigenesis (Bt) Δ-endotoxins are well known for their ability to control a variety of insect pests, including members of Lepidoptera, Coleoptera, and Diptera
Anthrax is a very real and dangerous threat to all people who come in contact with it. The bacterial infection is caused by the bacteriaium Bacillus anthracis. Anthrax is divided into three categories all are contracted in different ways. The first type is called Cutaneous Anthrax; this is where anthrax spores make contact with the skin. If there is a cut or a lesion then a person can be infected. Cutaneous Anthrax is the most common way to get anthrax, but is also the least lethal. The second type of anthrax is called Pulmonary Anthrax this is where a person inhales the spores of anthrax directly into the lungs. If this type of anthrax is left untreated it could lead to death. The third type of anthrax is called Gastrointestinal Anthrax, this form results from eating meat from animals that have been infected with the anthrax bacteria. This causes the intestinal tract to become infected and this from is almost always fatal. This particular mode of anthrax has never been seen in the United States.