Navigation Links
Scientists crack code of critical bacterial defense mechanism
Date:4/25/2010

COLUMBUS, Ohio Scientists have combined chemistry and biology research techniques to explain how certain bacteria grow structures on their surfaces that allow them to simultaneously cause illness and protect themselves from the body's defenses.

The researchers are the first to reproduce a specific component of this natural process in a test tube an essential step to fully understanding how these structures grow.

With the new method described, these and other researchers now can delve even deeper into the various interactions that must occur for these structures called lipopolysaccharides to form, potentially discovering new antibiotic targets along the way.

Lipopolysaccharides are composed primarily of polysaccharides strings of sugars that are attached to bacterial cell surfaces. They help bacteria hide from the immune system and also serve as identifiers of a given type of bacteria, making them attractive targets for drugs. But before a drug can be designed to inhibit their growth, scientists must first understand how polysaccharides are developed in the first place.

"We were able to answer some of the questions about how components of this growth system do their jobs. This will allow us to more fully characterize lipopolysaccharide biosynthesis in vitro, a process which may shed light on useful targets for developing antibiotic agents," said Robert Woodward, a graduate student in chemistry at Ohio State University and lead author of the study.

The study is published in the April 25 online edition of the journal Nature Chemical Biology.

The researchers used a harmless strain of Escherichia coli as a model for this work, which would apply to other E. coli strains and similar Gram-negative bacteria, a reference to how their cell walls are structured.

The surface of these bacteria house the lipopolysaccharide, which is a three-part molecular structure embedded into the cell membrane. Two sections of this structure are well understood, but the third, called the O-polysaccharide, has to date been impossible to reproduce.

Two significant challenges have hindered research efforts in this area: The five sugars strung together to compose this section of the molecule are difficult to chemically prepare in the lab, and one of the key enzymes that initiates the structure's growth process doesn't easily function in a water-based solution in a test tube.

Ohio State synthetic chemists and biochemists put their heads together to solve these two problems, Woodward said.

To produce the five-sugar chain, the researchers started with a chemically prepared building block containing a single sugar and introduced enzymes that generated a five-sugar unit from that single carbohydrate.

"The first part was done chemically, and in the second part, we used the exact same enzymes that are normally present in a bacterial cell to transform the single sugar into a five-sugar string," Woodward said.

Once these sugars join to make a five-sugar chain, a specific number of these chains are joined together to fully form the O-polysaccharide. A protein is required to connect those chains the protein that doesn't respond well to the test-tube environment.

Early attempts to produce this protein in the lab resulted in clumping structures that did not function. So Woodward and colleagues produced this protein in the presence of what are known as "chaperone" proteins.

"And basically what the chaperones do is help the protein fold into its correct state. We were able to produce the desired enzyme and also were able to verify that it was functional," Woodward said.

This protein is called Wzy. It is a sugar polymerase, or an enzyme that interacts with the five-sugar chain to begin the process of linking several five-sugar units together.

Getting this far into the process was important, but the researchers also completed one additional step to define yet another protein's role.

Wzy connected the five-sugar chains, but it did so with no defined limit to the number of five-sugar units involved, a feature that does not match the natural process. On an actual bacterial cell wall, the length of the polysaccharide falls within a relatively narrow range of the number of chains connected.

So the scientists introduced another protein, called Wzz, to the mixture. This protein is known as a "chain length regulator." With this protein in the mix, the lengths of the resulting polysaccharides were confined to a much more narrow range.

"We were able to replicate the exact polysaccharide biosynthetic pathway in vitro, getting the correct lengths," Woodward said. "This is important because now you can begin to look at a whole host of other properties in the system."

The group already started trying to answer one compelling question: whether the two proteins, Wzy and Wzz, have to interact to fully achieve formation of the polysaccharide.

"We've shown in some preliminary results that they do interact, but we haven't determined whether that interaction has any functional relevance," Woodward said.

With this knowledge in hand, researchers now have access to information about how all three parts of the lipopolysaccharide, the large biomolecule on Gram-negative bacteria cell surfaces, is formed. One thing they already knew is that the entire process takes place on an inner membrane and is then exported to the outer membrane on the cell surface.

Now that scientists can reproduce formation of the lipopolysaccharide, they can more directly characterize the export process a step in the pathway that serves as another potential antibiotic target, Woodward noted.


'/>"/>

Contact: Robert Woodward
woodward.69@osu.edu
614-292-8704
Ohio State University
Source:Eurekalert

Related biology news :

1. Scientists discover key step for regulating embryonic development
2. Scientists sever molecular signals that prolific parasite uses to puppeteer cells
3. Scientists create artificial human skin with biomechanical properties using tissue engineering
4. Brown scientists elected to American Academy of Arts and Sciences
5. Scripps Research scientists reveal how genetic mutations may cause type 1 diabetes
6. 2 Hopkins scientists awarded European honorary doctorates
7. Chinese scientists discover marker indicating the developmental potential of stem cells
8. Scientists find new genes for cancer, other diseases in plants, yeast and worms
9. Scripps Research scientists solve mystery of fragile stem cells
10. Ontario Cancer Institute, US scientists discover compound that kills lymphoma cells
11. UTHealth stem cell scientists explore treatments for blood disorders and lung diseases
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/29/2017)... 29, 2017  higi, the health IT company that ... North America , today announced a Series B ... of EveryMove. The new investment and acquisition accelerates higi,s ... to transform population health activities through the collection and ... higi collects and secures data today on behalf ...
(Date:3/27/2017)... , March 27, 2017  Catholic Health ... and Management Systems Society (HIMSS) Analytics for achieving ... Adoption Model sm . In addition, CHS previously ... U.S. hospitals using an electronic medical record (EMR). ... its high level of EMR usage in an ...
(Date:3/24/2017)... , Mar 24, 2017 Research and Markets ... System Market Analysis & Trends - Industry Forecast to 2025" ... ... grow at a CAGR of around 15.1% over the next decade ... industry report analyzes the market estimates and forecasts for all the ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... Calif. , Oct. 10, 2017 SomaGenics ... from the NIH to develop RealSeq®-SC (Single Cell), expected ... for profiling small RNAs (including microRNAs) from single cells ... Program highlights the need to accelerate development of approaches ... "New techniques for measuring levels ...
(Date:10/9/2017)... ... ... The award-winning American Farmer television series will feature 3 Bar Biologics in an ... on RFD-TV. , With global population estimates nearing ten billion people by 2050, ... a growing nation. At the same time, many of our valuable resources are becoming ...
(Date:10/7/2017)... Phoenix, Arizona (PRWEB) , ... ... ... than 15 years’ experience providing advanced instruments and applications consulting for microscopy ... the in-house expertise in application consulting, Nanoscience Analytical offers a broad range ...
(Date:10/6/2017)... D.C. (PRWEB) , ... October 06, 2017 , ... ... will host a lunch discussion and webinar on INSIGhT, the first-ever adaptive clinical ... Principal Investigator, Dana-Farber Cancer Institute. The event is free and open to the ...
Breaking Biology Technology: