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 Molecular Force Sensors
20.09.2017 | Max-Planck-Institut für Biochemie

nachricht Foster tadpoles trigger parental instinct in poison frogs
20.09.2017 | Veterinärmedizinische Universität Wien

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

Im Focus: Fast, convenient & standardized: New lab innovation for automated tissue engineering & drug

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.

MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...

Im Focus: Silencing bacteria

HZI researchers pave the way for new agents that render hospital pathogens mute

Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Molecular Force Sensors

20.09.2017 | Life Sciences

Producing electricity during flight

20.09.2017 | Power and Electrical Engineering

Tiny lasers from a gallery of whispers

20.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>