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Overview

Although most bacteria and other microbes will never cause infectious diseases in humans, many do, and those tiny stealth invaders are the focus of much current research in biochemistry and biology. Developing an understanding of the complex interactions between molecules—the molecular mechanisms—that allow microbes to assault our bodies is essential in the discovery of new medicines. Antibiotics, the current weapons in our arsenal against bacterial terrorists, are becoming obsolete as the bacteria mutate and antibiotic resistant forms flourish while their more susceptible siblings are wiped out. Treatments for viral infections, such as the common cold, have been even more elusive because viruses use the machinery of our own cells to reproduce. Antibiotics are completely ineffective against viruses because viruses are not cellular and cannot make more of themselves unless they are protectively established in our own cells.

In search of new cures, biochemists and other scientists study the proteins that do the dirty work of these terrorist organisms. A microbe’s job is to get a grip on the victim organism (host) and to avoid being taken out by the host’s immune system. At the molecular level, disease-causing organisms have virulence factors (proteins) that attach to binding-sites (also proteins) usually on the host cell’s outer membrane (plasma membrane). Researchers seek to understand these interactions in order to develop drugs that can keep an invader’s proteins from completing their mission. Often this means that the medicine must lock onto the harmful proteins or block the binding site on the plasma membrane of the host cell. The new medicines must have a sensitive guidance system so that they seek and destroy only the microbes and not the host. Investigating the molecular mechanisms of disease in order to design new drugs is also critical in treating genetic diseases and diseases associated with aging.

Why This Science Matters

Anyone who has experienced the misery of Strep throat knows that in spite of their microscopic size bacteria have far reaching effects on our quality of life: fever; chills; aching muscles; raw, burning throat; and fatigue. If the bacterium is anthrax, or the 0157:H7 strain of E. coli, instead of Streptococcus, things can quickly go from bad to worse, and even Strep has variations that are deadly. Also, people with compromised immune systems or immunosuppressant diseases often experience alarming symptoms from bacterial infections and many die. Pseudomonas bacteria can multiply out of control in the lungs of people with cystic fibrosis and can be deadly. Certain strains of Pseudomonas create a jelly-like layer around themselves that gives them resistance to antibiotics. Around the world, millions of people become sick each year from pathogens in water, either from drinking it or swimming in it. Others who have just had surgery contract bacterial infections sometimes caused by Staphylococcus aureus, referred to as Staph. Anthrax has become a concern due to recent bio-terrorist attacks.

When antibiotics first became available to treat disease, many people thought that bacteria would no longer pose a threat to humans or livestock. However, the rise of antibiotic resistant bacteria makes it clear that we have a long way to go. That is why research into the molecular mechanisms of bacterial infections is so important. Similar research seeks to understand the mechanisms by which other pathogens (disease-causing organisms), such as viruses, interact with our immune systems. Other research aims to understand the molecular mechanisms of non-infectious diseases, such as Alzheimer’s, cancer and heart disease.

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Teacher Credit: Lesson developed by Ann Marie Wellhouse, founder of River Valley Charter School, who currently teaches classes in science leadership and science investigations and has also taught biology and earth science.

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