Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Organelle’s discovery challenges theory, could alter approach to disease treatment

18.06.2003


Researchers looking inside a pathogenic soil bacterium have found an organelle, a subcellular pouch, existing independently from the plasma membrane. The discovery within a prokaryotic organism challenges the theory on the origin of eukaryotic organelles and suggests a targeted approach to killing many disease-causing organisms.


Acidocalcisomes (the black spheres) as viewed in a trypanosome, a family of parasites that cause African sleeping sickness, Chagas disease and leishmaniasis and the first organisms where Docampo found this organelle. The cell is approximately 10 microns long and 4 microns wide. Courtesy of Kildare Miranda



"The organelle we found in the bacterium Agrobacterium tumefaciens is practically identical to the organelle called acidocalcisome in unicellular eukaryotes," said Roberto Docampo, a professor of veterinary pathobiology in the College of Veterinary Medicine at the University of Illinois at Urbana-Champaign.

Docampo began researching these organelles in 1994. He soon determined that a tiny granule in yeast, fungi and bacteria, thought to be for storage, was a fully operational organelle containing pyrophosphatase, a pump-like enzyme that allows proton transport. He named it an acidocalcisome for its acidic and calcium components. In 2000, he reported its existence in Plasmodium berghei, a malaria-causing eukaryotic parasite.


The newest discovery appeared in a paper published online this month by the Journal of Biological Chemistry. The paper, by Docampo and colleagues at the Center for Zoonoses Research and Laboratory of Molecular Parasitology at Illinois, will be published in a later print edition of the journal.

Agrobacterium tumefaciens is a prokaryote, a unicellular organism lacking membrane-bound nuclei. It causes crown gall disease in many broad-leaved plants but also is a favored tool for plant breeding because of its model system of DNA transfer into the hosts it invades. Samples were provided to Docampo’s team by biotechnology researcher Stephen K. Farrand, a professor of microbiology and crop sciences at Illinois.

Bacteria and other prokaryotes generally lack an endomembrane system.

Thus bacteria are presumed to lack compartments such as organelles not somehow linked to the plasma membrane ringing the organisms.

"What we describe is a discrete organelle independent of the plasma membrane," Docampo said. "It has a proton pump in its membrane, which is used to maintain its interior acidic content. This has never been described before in a bacterium."

The existence of discrete organelles is a defining component of unicellular eukaryotes, which have membrane-bound nuclei and specialized structures in their cell boundaries. The evolution of eukaryotic organelles "is a matter of extensive debate," Docampo said. The principle of endosymbiosis says that as microorganisms engulfed others, then new, membrane-surrounded organelles emerged in eukaryotes.

"It appears that this organelle has been conserved in evolution from prokaryotes to eukaryotes, since it is present in both. This argues against the belief that all eukaryotic organelles were formed when early eukaryotes swallowed prokaryotes," he said.

Using transmission electron and immunoelectron microscopy and X-ray microanalysis on the bacterium, researchers got a highly magnified and illuminated view.

They applied a fluorescent dye into the suspected organelle. They saw a membrane around it. The dye stained areas only within it, not in the cytosol. Serum containing antibodies to peptides related to pyrophosphatase unveiled this pump-like enzyme, and other staining techniques revealed high levels of polyphosphate only in the organelle.

Many parasites such as those that cause malaria, African sleeping sickness and toxoplasmosis and bacteria that contain these acidocalcisome organelles are pathogens.

Some pharmaceutical approaches have targeted pyrophosphate-related enzymes, Docampo said. "Our suggestion is that if drugs specifically targeted these organelles, you may be able to kill the entire organisms."

In addition to Docampo, other Illinois researchers were Manfredo Seufferheld, Mauricio C.F. Vieira, Felix A. Ruiz, Claudia O. Rodrigues and Silvia N.J. Moreno. The National Institutes of Health funded the research through a grant to Docampo.

Jim Barlow | UIUC
Further information:
http://www.news.uiuc.edu/scitips/03/0617organelle.html

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

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

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>