Featured Research

from universities, journals, and other organizations

Scientists Uncover Break-And-Entry Strategy Of Disease-Causing Bacteria

Date:
January 12, 2001
Source:
Washington University School Of Medicine
Summary:
As bacteria become resistant to current antibiotics, scientists are searching for the root causes of infection in order to develop more effective treatments. Researchers at Washington University School of Medicine in St. Louis have come one step closer to understanding how bacteria such as Streptococcus and Staphylococcus operate: These pathogens introduce their toxins by punching holes in the host-cell membrane.

St. Louis, Jan. 12, 2001 —- As bacteria become resistant to current antibiotics, scientists are searching for the root causes of infection in order to develop more effective treatments. Researchers at Washington University School of Medicine in St. Louis have come one step closer to understanding how bacteria such as Streptococcus and Staphylococcus operate: These pathogens introduce their toxins by punching holes in the host-cell membrane. The cover of the Jan. 12 issue of Cell features the research. Scientists have made great strides in understanding how Gram-negative bacteria, such as Salmonella and E. coli, infiltrate host cells and establish infection. However, a second class of bacteria called Gram-positive causes human diseases such as strep throat, necrotizing faciitis, toxic shock syndrome and rheumatic fever. "Gram-positive organisms are responsible for five of the top six bacterial infections that are now resistant to multiple antibiotics available today," says study leader Michael G. Caparon, Ph.D., associate professor of molecular microbiology.

The first authors of the study are M.D./Ph.D. student John C. Madden and Natividad Ruiz, Ph.D., now at Princeton University.

Gram-negative bacteria inject previously healthy cells with toxins that disrupt essential processes. Several laboratories have visualized needle-like projections from these bacteria into host cells. Presumably, the projections serve as syringes.

Caparon and colleagues discovered that Gram-positive bacteria use an equivalent technique. Most Gram-positive pathogens contain proteins called cholesterol-dependent cytolysins (CDC). Because these molecules have persisted throughout the evolution of this diverse group, they might play a critical role in infection, the researchers surmised.

Studying the molecular basis of infection has been difficult in the past. But thanks to improved techniques, Caparon’s group was able to manipulate the bacteria genetically. The researchers made defined mutants of Streptococcus pyogenes, the Gram-positive, flesh-eating bacterium that also causes strep throat and impetigo. By studying the consequences of the genetic defects, they uncovered specific points in the infection pathway.

S. pyogenes contains a CDC called streptolysin O (SLO). The researchers found that this protein chips away at the outer membranes of targeted cells, creating large holes or pores. SLO does not enter cells, however. Instead, a protein called SPN (S. pyogenes NAD-glycohydrolase) gets into cells after SLO has done its work. "SLO appears to pave the way for the entry of SPN, which is useless outside cells," Caparon says. "Once inside, SPN manipulates certain cellular processes."

His group hopes to determine how SPN affects host cells. Once scientists learn exactly how Gram-positive bacteria cause disease, they can step back and see where they can intervene. "New classes of current antibiotics simply buy us a little time. We have to come up with new ways of thinking about the problem," Caparon says.

Madden JC, Ruiz N, Caparon M. Cytolysin-mediated translocation (CMT): A functional equivalent of Type III Secretion in Gram-positive bacteria. Cell, vol. 104 pp. 1-20, Jan. 12, 2001.

Funded by Public Health Service Grants from the National Institutes of Health.


Story Source:

The above story is based on materials provided by Washington University School Of Medicine. Note: Materials may be edited for content and length.


Cite This Page:

Washington University School Of Medicine. "Scientists Uncover Break-And-Entry Strategy Of Disease-Causing Bacteria." ScienceDaily. ScienceDaily, 12 January 2001. <www.sciencedaily.com/releases/2001/01/010111194856.htm>.
Washington University School Of Medicine. (2001, January 12). Scientists Uncover Break-And-Entry Strategy Of Disease-Causing Bacteria. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2001/01/010111194856.htm
Washington University School Of Medicine. "Scientists Uncover Break-And-Entry Strategy Of Disease-Causing Bacteria." ScienceDaily. www.sciencedaily.com/releases/2001/01/010111194856.htm (accessed July 24, 2014).

Share This




More Plants & Animals News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Dogs Appear To Become Jealous Of Owners' Attention

Dogs Appear To Become Jealous Of Owners' Attention

Newsy (July 23, 2014) A U.C. San Diego researcher says jealousy isn't just a human trait, and dogs aren't the best at sharing the attention of humans with other dogs. Video provided by Newsy
Powered by NewsLook.com
Professor Creates Site Revealing Where People's Cats Live

Professor Creates Site Revealing Where People's Cats Live

Newsy (July 23, 2014) ​It's called I Know Where Your Cat Lives, and you can keep hitting the "Random Cat" button to find more real cats all over the world. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins