Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nasty bacteria need sunlight to do their worst

27.08.2007
Certain types of bacteria have sunlight-sensing molecules similar to those found in plants, according to a new study. Surprisingly, at least one species—responsible for causing the flu-like disorder Brucellosis—needs light to maximize its virulence. The work suggests an entirely new model for bacterial virulence based on light sensitivity.

The paper was authored by an international team* of collaborators including Trevor Swartz, lead author who was a former postdoctoral and visiting investigator at Carnegie’s Department of Plant Biology at the time of the study, and Winslow Briggs and Tong-Seung Tseng currently at the department. The research appears in the August 24 issue of the journal Science. It is the first detailed study into the function of plant-like light-sensing molecules in bacteria.

“The central message is that many bacteria have signaling proteins that contain the same light-absorbing domain as those found in the higher plants,” Briggs explains. “One of these is a vicious pathogen called Brucella. A species of Brucella is a serious pathogen of cattle that causes abortion of calves, and another species is a nasty pathogen of humans.”

The bacterial sensors are closely related to phototropins—the light receptor molecules that cause a plant to grow toward a light source. They share a protein sequence called a LOV (pronounced “love”) domain, so named because it can detect light, oxygen, and/or voltage. Briggs and his colleagues were the first to discover and describe plant LOV domains in 1998.

... more about:
»Brucella »Domain »Kinase »LOV »Swartz »bacterial »virulence

LOV-domain proteins have been found in more than 100 different bacteria. For the purposes of this study, the researchers narrowed the field to a handful of candidates with well-known LOV sequences that closely resemble those in plants. They eventually settled on four species: Brucella melitensis, Brucella abortus, Erythrobacter litoralis and Pseudomonas syringae.

In the case of B. abortus, and possibly others, the presence of a LOV domain is more than mere coincidence. When the researchers disabled the LOV-domain protein gene in this species, its virulence—measured as the ability to reproduce efficiently enough to cause disease—dropped to less than 10% of normal, “wild-type” bacteria.

In a simple experiment involving two layers of light-blocking aluminum foil, they achieved a similar drop in virulence, demonstrating that B. abortus depends on sunlight to do its dirty work.

“Brucella has been extensively studied for years because of its threat to livestock and the effect it has on our food supply—one of the key reasons we pasteurize milk is to prevent infection by Brucella,” explained Swartz. “But no one has previously demonstrated any type of light response in Brucella’s lifecycle. This is an exciting result that could possibly provide for a novel therapeutic avenue to treat and prevent infection.”

“People studying non-photosynthetic bacteria, whether the bugs are pathogenic or not, pay no attention to light conditions and are completely unaware that light might play some essential role in their physiology,” Briggs added.

When it is in the dark, a LOV domain uses weak chemical bonds to hold onto a small molecular group known as a chromophore. When it absorbs light, however, the LOV domain temporarily tightens its grip on the chromophore by forming a more stable bond. This reaction is essentially a biochemical switch, and when the light source is blocked or removed, the LOV domain relaxes its grip on the chromophore once again. Activated LOV domains can switch on yet another signaling molecule, known as a kinase, forming a coupled biochemical pathway referred to as a "two-component system."

The function of LOV proteins is fairly well documented in plants. Although researchers had previously documented LOV proteins in bacteria, Briggs, Tseng, Swartz, and their colleagues are the first to examine their function in detail. They found that bacterial LOV domains activate a common signaling pathway that begins with a specific type of kinase known as histidine kinase.

“Bacteria have a large collection of these so-called histidine kinases that are activated by nutrients such as sugar and amino acids, or toxic substances,” Briggs said. “Our work is the first ever to demonstrate a light-activated histidine kinase in a bacterium and demonstrate that it plays an essential role in bacterial virulence.”

*In addition to Briggs, Tseng, and Swartz, co-authors on the paper are: Marcus A. Frederickson and Roberto A. Bogomolni of the University of California, Santa Cruz; Gastón Paris and Fernando A. Goldbaum of the Fundacion Instituto Leloir, CONICET, Buenos Aires, Argentina; Diego J. Comerci and Rodolfo A. Ugalde of the Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín, CONICET, San Martín, Argentina; Gireesh Rajashekara of the University of Wisconsin and Ohio State University; Jung-Gun Kim and Mary Beth Mudgett of Stanford University; and Gary A. Splitter of the University of Wisconsin.

**Swartz initiated the study while a research faculty member at the University of California, Santa Cruz; he is currently at Genentech, Inc.

This research was funded by the National Science Foundation, the National Institutes of Health, the US Department of Agriculture, the Howard Hughes Medical Institute, the Binational Agricultural Research and Development Fund, and the Agencia Nacional de Promoción Científica y Tecnológica (Argentina).

The Carnegie Institution of Washington (www.carnegieinstitution.org), a private nonprofit organization, has been a pioneering force in basic scientific research since 1902. It has six research departments: the Geophysical Laboratory and the Department of Terrestrial Magnetism, both located in Washington, D.C.; The Observatories, in Pasadena, California, and Chile; the Department of Plant Biology and the Department of Global Ecology, in Stanford, California; and the Department of Embryology, in Baltimore, Maryland.

Winslow Briggs | EurekAlert!
Further information:
http://www.stanford.edu
http://www.carnegieinstitution.org

Further reports about: Brucella Domain Kinase LOV Swartz bacterial virulence

More articles from Life Sciences:

nachricht Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg

nachricht Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>