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 Tag it EASI – a new method for accurate protein analysis
20.06.2018 | Max-Planck-Institut für Biochemie

nachricht How to track and trace a protein: Nanosensors monitor intracellular deliveries
19.06.2018 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Could this material enable autonomous vehicles to come to market sooner?

20.06.2018 | Materials Sciences

Innovative autonomous system for identifying schools of fish

20.06.2018 | Information Technology

Controlling robots with brainwaves and hand gestures

20.06.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>