Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers witness assembly of molecules critical to protein function

18.06.2008
A Virginia Tech research group lead by two biochemistry graduate students has isolated proteins responsible for the iron-sulfur cluster assembly process and witnessed the necessary protein interactions in vivo – within a cell. They have captured pathway intermediates and observed protein interactions between the two major players in iron-sulfur cluster assembly.

Iron-sulfur clusters are critical to life on earth. They are necessary for protein function in cellular processes, such as respiration in humans and other organisms and photosynthesis by plants. "But we do not understand how Fe-S molecules are made or the specifics of how they bond," said Callie Raulfs of Christiansburg, Va. "It does not happen spontaneously. It has to be regulated."

Diseases such as Friedrich's ataxia and several types of anemia are a result of iron-sulfur cluster (ISC) assembly malfunctions.

Using genetic and biochemical techniques, Ph.D. students Raulfs and Ina P. O'Carroll, of Tirana, Albania, have isolated components of the ISC machinery in the process of making iron-sulfur clusters. "This work provides insight into the sequential steps of the iron-sulfur cluster assembly process, helping to explain how molecules of iron and sulfur are synthesized and distributed in cells," said O'Carroll.

The work, "In vivo iron-sulfur cluster formation," by Raulfs, O'Carroll, Virginia Tech post-doctoral associates Patricia C. Dos Santos of Brazil and Mihaela-Carmen Unciuleac of Romania, and Dennis R. Dean of Blacksburg, professor of biochemistry and director of the Fralin Biotechnology Center at Virginia Tech, has been published in the Proceedings of the National Academy of Science (PNAS) Online Early Edition the week of June 16-20, 2008.

Previous studies by Dean and others have demonstrated that proteins can assemble clusters from components in vitro systems – that is, outside of an organism. Ten years ago, working with nitrogen-fixation systems, Dean's lab was the first to discover ISC proteins. Now Dean's students, Raulfs and O'Carroll, are the first to witness the assembly process in vivo – within a cell.

"The cool thing is we've come up with a way to observe ISC proteins from their native host with a cluster attached," said O'Carroll. "The system also allows us to capture different phases of the process."

The students have isolated three different intermediates of the ISC proteins involved in intercellular biosynthesis – or the cluster assembly process.

Rather than multiplying the proteins by placing them in E. coli, the Virginia Tech team used Azotobacter vinelandii, an aerobic, soil microbe that fixes nitrogen from the atmosphere, to obtain natural levels of the ISC proteins. "A vinelandii grows quickly and keeps the interior of the cell free of oxygen, which is important, since oxygen can destroy Fe-S clusters," said Raulfs, who first isolated a protein complex with a cluster attached, providing in vivo evidence that the two proteins get together and form a cluster.

"Because we are isolating proteins from the cell, we are also able to observe interactions between different Fe-S cluster asembly proteins," said O'Carroll. "We have been able to isolate a complex between the two major players in iron-sulfur assembly, the cluster assembly scaffold (IscU) and the sulfur-delivery protein (IscS)."

The methodology is to add a histidine amino acid tag to the ISC proteins "so we can fish the proteins out of the cell," said O'Carroll.

"Because we are fishing the cluster-containing protein out of the cell that has all of the other assembly proteins present at physiological levels, we are able to observe what else comes with the protein. What was really exciting in this case was that we saw large amounts of one of the other iron sulfur cluster assembly protein, IscS." said O'Carroll.

The work marks the first time researchers have been able to observe ISC proteins from the balanced environment of the native cell.

Next, they plan to determine the role of the individual genes in the set that produces ISC proteins in order to determine the effect of each gene on the assembly process. "The goal is to determine the events and the order in the ISC assembly process so we can figure out how cells make clusters and deliver them to specific target proteins," said O'Carroll.

The researchers are now developing a system that others can use to study proteins.

Susan Trulove | EurekAlert!
Further information:
http://www.vt.edu

More articles from Life Sciences:

nachricht The hidden structure of the periodic system
17.06.2019 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht Tiny probe that senses deep in the lung set to shed light on disease
17.06.2019 | University of Edinburgh

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The hidden structure of the periodic system

The well-known representation of chemical elements is just one example of how objects can be arranged and classified

The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...

Im Focus: MPSD team discovers light-induced ferroelectricity in strontium titanate

Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.

Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...

Im Focus: Determining the Earth’s gravity field more accurately than ever before

Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.

The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...

Im Focus: Tube anemone has the largest animal mitochondrial genome ever sequenced

Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.

The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....

Im Focus: Tiny light box opens new doors into the nanoworld

Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.

Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

Novel communications architecture for future ultra-high speed wireless networks

17.06.2019 | Information Technology

Climate Change in West Africa

17.06.2019 | Earth Sciences

Robotic fish to replace animal testing

17.06.2019 | Ecology, The Environment and Conservation

VideoLinks
Science & Research
Overview of more VideoLinks >>>