Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Purdue scientists reveal how bacteria build homes inside healthy cells

21.12.2011
Bacteria are able to build camouflaged homes for themselves inside healthy cells - and cause disease - by manipulating a natural cellular process.

Purdue University biologists led a team that revealed how a pair of proteins from the bacteria Legionella pneumophila, which causes Legionnaires disease, alters a host protein in order to divert raw materials within the cell for use in building and disguising a large structure that houses the bacteria as it replicates.

Zhao-Qing Luo, the associate professor of biological sciences who headed the study, said the modification of the host protein creates a dam, blocking proteins that would be used as bricks in cellular construction from reaching their destination. The protein "bricks" are then diverted and incorporated into a bacterial structure called a vacuole that houses bacteria as it replicates within the cell. Because the vacuole contains materials natural to the cell, it goes unrecognized as a foreign structure.

"The bacterial proteins use the cellular membrane proteins to build their house, which is sort of like a balloon," Luo said. "It needs to stretch and grow bigger as more bacterial replication occurs. The membrane material helps the vacuole be more rubbery and stretchy, and it also camouflages the structure. The bacteria is stealing material from the cell to build their own house and then disguising it so it blends in with the neighborhood."

The method by which the bacteria achieve this theft is what was most surprising to Luo.

The bacterial proteins, named AnkX and Lem3, modify the host protein through a biochemical process called phosphorylcholination that is used by healthy cells to regulate immune response. Phosphorylcholination is known to happen in many organisms and involves adding a small chemical group, called the phosphorylcholine moiety, to a target molecule, he said.

The team discovered that AnkX adds the phosphorylcholine moiety to a host protein involved in moving proteins from the cell's endoplasmic reticulum to their cellular destinations. The modification effectively shuts down this process and creates a dam that blocks the proteins from reaching their destination.

The bacterial protein Lem3 is positioned outside the vacuole and reverses the modification of the host protein to ensure that the protein "bricks" are free to be used in creation of the bacterial structure.

This study was the first to identify proteins that directly add and remove the phosphorylcholine moiety, Luo said.

"We were surprised to find that the bacterial proteins use the phosphorylcholination process and to discover that this process is reversible," he said. "This is evidence of a new way signals are relayed within cells, and we are eager to investigate it."

The team also found that the phosphorylcholination reaction is carried out at a specific site on the protein called the Fic domain. Previous studies had shown this site induced a different reaction called AMPylation.

It is rare for a domain to catalyze more than one reaction, and it was thought this site's only responsibility was to transfer the chemical group necessary for AMPylation, Luo said.

"Revealing that this domain has dual roles is very important to identify or screen for compounds to inhibit its activity and fight disease," he said. "This domain has a much broader involvement in biochemical reactions than we thought and may be a promising target for effective treatments."

During infection bacteria deliver hundreds of proteins into healthy cells that alter cellular processes to turn the hostile environment into one hospitable to bacterial replication, but the specific roles of only about 20 proteins are known, Luo said.

"In order to pinpoint proteins that would be good targets for new antibiotics, we need to determine their roles and importance to the success of infection," he said. "We need to understand at the biochemical level exactly what these proteins do and how they take over natural cellular processes. Then we can work on finding ways to block these activities, stop the infection and save lives."

A paper detailing their National Institutes of Health-funded work is published in the current issue of the Proceedings of National Academy of Sciences. In addition to Luo, Purdue graduate student Yunhao Tan and Randy Ronald of Indiana University co-authored the paper.

Luo next plans to use the bacterial proteins as a tool to learn more about the complex cellular processes controlled by phosphorylcholination and to determine the biochemical processes role in cell signaling.

Writer: Elizabeth K. Gardner, 765-494-2081, ekgardner@purdue.edu

Source: Zhao-Wing Luo, 765-496-6697, luoz@purdue.edu

Elizabeth K. Gardner | EurekAlert!
Further information:
http://www.purdue.edu

More articles from Life Sciences:

nachricht Seeing on the Quick: New Insights into Active Vision in the Brain
15.08.2018 | Eberhard Karls Universität Tübingen

nachricht New Approach to Treating Chronic Itch
15.08.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Unraveling the nature of 'whistlers' from space in the lab

15.08.2018 | Physics and Astronomy

Diving robots find Antarctic winter seas exhale surprising amounts of carbon dioxide

15.08.2018 | Earth Sciences

Early opaque universe linked to galaxy scarcity

15.08.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>