Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Bacteria that cause tooth decay able to survive without important biochemical pathway


’Essential’ system may be unnecessary in S. mutans

Leave it to the bacteria that cause tooth decay to be able to live without something all cells were thought to require.

Scientists have long believed a certain biochemical pathway involved in the folding and delivery of proteins to cell membranes is essential for survival. Now University of Florida researchers have discovered that Streptococcus mutans, the decay-causing organism that thrives in many a mouth, can do just fine without it.

The findings, reported this month in the Proceedings of the National Academy of Sciences, have rocked the cellular biology scientific community, which has long considered the pathway to be crucial. The report may also explain why strains of the bacteria can survive in the harsh acidic environment they create in the mouth.

"We were met with skepticism … because the dogma was that this biochemical pathway is key for all living cells," said study investigator Jeannine Brady, Ph.D., an associate professor of oral biology at the UF College of Dentistry. "As far as we know, this is the first example of any bacteria that can cope without this pathway; all of the existing literature indicated it is vital."

The signal recognition particle, or SRP, pathway is a primary mechanism by which proteins are chaperoned from cellular assembly lines, where they are made, to the protective outer surface of the cells, where they are inserted. Without a steady infusion of proteins, the membrane weakens and the cell - in this case, a bacterium - becomes unable to protect itself from harsh environmental conditions.

In the human mouth, its natural environment, it is typically S. mutans that goes on the attack. When sugary foods are eaten, the S. mutans population explodes, excreting lactic acid as it digests sugar. The acid makes life difficult for other helpful bacteria and demineralizes tooth enamel, causing decay.

According to the U.S. Centers for Disease Control and Prevention, 95 percent of adult Americans suffer from tooth decay. Considered by the U.S. surgeon general to be a "silent epidemic," tooth decay is a chronic childhood disease that affects five times more children than asthma and is estimated to result in 51 million lost school hours.

In an effort to understand how best to combat the tooth-decaying properties of S. mutans, Brady and her team set out to learn how the organism was able to survive its own acid. To find out, the researchers tinkered with systematically turning off several genes, individually and in combination, to see how the bacteria responded.

"We found S. mutans can survive, with normal growth, without the SRP pathway," said Adnan Hasona, Ph.D., a research assistant professor of oral biology and the study’s lead author.

The bacteria altered to lack SRP components were able to adapt and survive gradual increases in acid resulting from their own metabolism, suggesting a backup pathway was in place.

But, like goldfish dropped in new water, the altered bacteria could not contend with sudden environmental change. When artificially shocked with acid to a pH below that where tooth demineralization begins, the altered bacteria became sick and unable to grow. Shocking the bacteria with other environmental stressors, such as high salt levels or the presence of hydrogen peroxide, also caused them to weaken, Hasona said.

"So, at least in this organism, we learned the SRP pathway seems to enable it to respond rapidly to environmental stress, but it was not at all necessary for the organism’s viability during non-stress conditions," Brady said.

Brady’s team surmised that two other molecules, called YidC1 and YidC2, might be acting as alternate routes for protein delivery in the absence of the SRP pathway. They tested their hypothesis and found that S. mutans could continue to function in non-stress conditions without the SRP and YidC1 genes, but not without the YidC2 and SRP simultaneously.

"The fact that the bacteria could survive without the SRP pathway was the most striking finding for scientists in the membrane protein insertion field," said Ross E. Dalbey, Ph.D., a professor of chemistry at The Ohio State University. "The big question now is discovering how these proteins are targeted in the absence of the SRP pathway, and I think that will be an important area of future research."

Dalbey said the YidC2 and the SRP pathway could become targets in fighting tooth decay because they have been shown to enable S. mutans to grow in acidic conditions. Additionally, the YidC molecule has been demonstrated to be important to bacterial virulence and growth and has the potential to become a target in fighting infectious diseases, he said.

"Really, we started with a very basic question related primarily to S. mutans, ’how does this bacteria tolerate acid?’" said Brady. "Asking that question has opened the door much more widely to learning things that are more fundamental about how living organisms insert proteins and how membrane function is determined by proteins.

"We now know that things are not always as straightforward as they seem," she said.

Lindy McCollum-Brounley | EurekAlert!
Further information:

More articles from Health and Medicine:

nachricht Advanced analysis of brain structure shape may track progression to Alzheimer's disease
26.10.2016 | Massachusetts General Hospital

nachricht Indian roadside refuse fires produce toxic rainbow
26.10.2016 | Duke University

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

How nanoscience will improve our health and lives in the coming years

27.10.2016 | Materials Sciences

OU-led team discovers rare, newborn tri-star system using ALMA

27.10.2016 | Physics and Astronomy

'Neighbor maps' reveal the genome's 3-D shape

27.10.2016 | Life Sciences

More VideoLinks >>>