Bacteria have evolved a unique chemical mechanism to become antibiotic-resistant

Apr 28, 2011
Scientists have discovered a novel strategy by which antibiotic-resistant bacteria change their genetic make-up to evade multiple antibiotics. For the first time, scientists have been able to paint a detailed chemical picture of how a particular strain of bacteria has evolved to become resistant to antibiotics. The research is a key step toward designing compounds to prevent infections by recently evolved, drug-resistant "superbugs" that often are found in hospitals, as well as in the general population. A paper describing the research, by a team led by Squire Booker at Penn State University, will be posted by the journal Science on its early-online Science Express site on April 28, 2011. Credit: National Institutes of Health

For the first time, scientists have been able to paint a detailed chemical picture of how a particular strain of bacteria has evolved to become resistant to antibiotics. The research is a key step toward designing compounds to prevent infections by recently evolved, drug-resistant "superbugs" that often are found in hospitals, as well as in the general population.

A paper describing the research, by a team led by Squire Booker, an associate professor in the department of chemistry and the department of biochemistry and molecular biology at Penn State University, will be posted by the journal Science on its early-online site on 28 April. This paper is a continuation of research led by Booker published in another paper in Science earlier this month.

The team began by studying a protein made by a recently evolved "superbug." Booker explained that, several years ago, genetic studies had revealed that Staphylococcus sciuri -- a non-human -- had evolved a new gene called cfr. The protein created by this gene had been found to play a key role in one of the bacterium's mechanisms of antibiotic resistance. Later, the same gene was found to have crossed over into a strain of -- a very common kind of bacteria that constitutes part of the flora living in the human nose and on the skin, and which is now the cause of various antibiotic-resistant infections. Because this gene often is found within a mobile DNA element, it can move easily from a non-human pathogen to other species of bacteria that infect humans. "The gene, which has been found in Staphylococcus aureus isolates in the United States, Mexico, Brazil, Spain, Italy, and Ireland, effectively renders the bacteria resistant to seven classes of ," Booker explained. "Clearly, bacteria with this gene have a distinct . However, until now, the detailed process by which the protein encoded by that gene affected the of the bacteria was unclear; that is, we didn't have a clear 3D picture of what was going on at the molecular level."

To solve the chemical mystery of how such bacteria outsmart so many antibiotics, Booker and his team investigated how the Cfr protein accomplishes a task called methylation -- a process by which enzymes add a small molecular tag to a particular location on a nucleotide -- a molecule that is the structural unit of RNA and DNA. When this molecular tag is added by a protein called RlmN, it facilitates the proper functioning of the bacterial ribosome -- a gigantic macromolecular machine that is responsible for making proteins that bacteria need to survive. Many classes of antibiotics bind to the ribosome, disrupting its function and thereby killing the bacteria. The Cfr protein performs an identical function as the RlmN protein, but it adds the molecular tag at a different location on the same nucleotide. The addition of the tag blocks binding of antibiotics to the ribosome without disrupting its function. "What had perplexed scientists is that the locations to which RlmN and Cfr add molecular tags are chemically different from all others to which tags routinely are appended, and should be resistant to modification by standard chemical methods," Booker said. "What we've discovered here is so exciting because it represents a truly new chemical mechanism for methylation. We now have a very clear chemical picture of a very clever mechanism for antibiotic resistance that some have evolved."

Booker also said he believes the next step will be to use this new information to design compounds that could work in conjunction with typical antibiotics. "Because we know the specific mechanism by which bacterial cells evade several classes of antibiotics, we can begin to think about how to disrupt the process so that standard antibiotics can do their jobs," he said.

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Skeptic_Heretic
5 / 5 (3) Apr 28, 2011
For the first time, scientists have been able to paint a detailed chemical picture of how a particular strain of bacteria has evolved to become resistant to antibiotics. The research is a key step toward designing compounds to prevent infections by recently evolved, drug-resistant "superbugs" that often are found in hospitals, as well as in the general population.

Although this is a great advancement, I think it is overly optimistic. The real threat of bacterial resistance is presented by horizontal gene transfer between species of bacteria, which we've discovered happens far more readily and often than originally thought.
jamesrm
not rated yet Apr 28, 2011
Must have missed this
"Because this gene often is found within a mobile DNA element, it can move easily from a non-human pathogen to other species of bacteria that infect humans."
epsi00
not rated yet Apr 28, 2011
This is good news. Really good. Not sure how long it's going to take for the scientists to come up with something that can defeat bacterial resistance to antibiotics. And not sure how long it will take the bacteria to come up with a new process to evolve new resistance.
Fig1024
5 / 5 (2) Apr 28, 2011
And still, only about 30-40% of Americans believe in evolution.
Even if that number was 80%, it's still be unflattering.
Mahal_Kita
1 / 5 (3) Apr 29, 2011
And still, only about 30-40% of Americans believe in evolution.
Even if that number was 80%, it's still be unflattering.


The argument could very well be that such a remarkable step in the organisms efficiency must be contributed to the 'Hand of God.' Everything we humans experienced since we are banned from Paradise is punishment, and the punishment is ongoing.
ComputerWiz
not rated yet Apr 29, 2011
Everything we humans experienced since we are banned from Paradise is punishment, and the punishment is ongoing.

Some of us think that, instead of being "banned from Paradise", we were given the priceless gift of Independence.
unknownorgin
not rated yet Apr 30, 2011
I am glad to see this article properly identify hospitals as sources of infection. Because of the concentration of infected patients the bacteria rides on lint from the beds and out into the comunity through the ventelation system to infect more people and increase the problem. Hospitals will not sterlize thier exhust air unless forced by law to do so because they could be found liable for health care costs incurred by people living near the hospital. This research will save alot of lives and show that proper sanitation is key to stopping this deadly superbug.
Beard
not rated yet May 01, 2011
The argument could very well be that such a remarkable step in the organisms efficiency must be contributed to the 'Hand of God.' Everything we humans experienced since we are banned from Paradise is punishment, and the punishment is ongoing.


What an absolutely miserable and defeatist worldview. No wonder it was so popular during the Dark Ages.
Megadeth312
5 / 5 (1) May 01, 2011
@unknownorgin

comunity - Community
ventelation - Ventilation
sterlize - Sterilize
thier - Their
exhust - Exhaust
alot - A lot

:)
jmcanoy1860
not rated yet May 03, 2011

The argument could very well be that such a remarkable step in the organisms efficiency must be contributed to the 'Hand of God.' Everything we humans experienced since we are banned from Paradise is punishment, and the punishment is ongoing.


You are talking about the same crap jebus supposedly died to atone for right?

Did you just refer to something being "contributed to the hand of God." Typos are one thing. Not using words correctly is another.

Your explanation still requires a mechanism. Magic man and Magic is not a mechanism. Perhaps you should have CONTRIBUTED more to your education and less to tithes.
Javinator
5 / 5 (1) May 03, 2011
And still, only about 30-40% of Americans believe in evolution.
Even if that number was 80%, it's still be unflattering.


The argument could very well be that such a remarkable step in the organisms efficiency must be contributed to the 'Hand of God.' Everything we humans experienced since we are banned from Paradise is punishment, and the punishment is ongoing.


Or the Matrix.
Skeptic_Heretic
not rated yet May 03, 2011
Everything we humans experienced since we are banned from Paradise is punishment, and the punishment is ongoing.
Decreased mortality, longer life spans, fewer deaths during childhood, organized society, affluence, the internet....

Yep, real terrible punishment going on. If anything, it appears paradise really sucks compared to punishment. Are you sure your god is benevolent?