http://www.physorg.com/news132856182.html

 

Published: 15 hours ago, 17:29 EST, June 16, 2008

 

Researchers witness assembly of molecules critical to protein function

 

Depicted is a molecular representation of a four iron- four sulfur cluster in which the sulfur is shown in yellow and iron in green. Credit: Callie Raulfs

 

 

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 Friedreich'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.

Source: Virginia Tech

The legacy of Marie Schlau: literature to help cure Friedreich's Ataxia

If you feel like reading an unputdownable novel while collaborating with a just and solidary cause, "The Legacy of Marie Schlau" is your book! 100% of all funds raised will be dedicated to medical research to find a cure for Friedreich's Ataxia, a neurodegenerative disease that affects mostly young people, shortening their life expectancy and confining them to a wheelchair.

The life of Marie Schlau, a German Jewish girl born in 1833 hides great unsolved mysteries: accidents, disappearances, enigmas, unknown diagnoses, disturbing murders, love, tenderness, greed, lies, death ... alternatively a different story unfolds every time and takes us closer to the present. Thus, there are two parallel stories unravelling, each in a different age and place, which surprisingly converge in a revelatory chapter.

Paperback and Kindle versions for "The legacy of Marie Schlau" available for sale at Amazon now!

https://www.amazon.com/Legacy-Marie-Schlau-collective-Friedreichs-ebook/dp/B01N28AFWZ

 

Research projects currently being financed by BabelFAmily

Currently, BabelFAmily is financing two promising research projects aimed at finding a cure for Friedreich's Ataxia. Whenever you make a donation to us or purchase a copy of "The legacy of Marie Schlau", this is where all funds raised will be devoted to:

1) Gene Therapy for Friedreich's Ataxia research project:

https://www.irbbarcelona.org/en/news/international-patient-advocates-partner-to-fund-spanish-gene-therapy-project-to-treat

The project is the result of an initiative of Spanish people affected by this rare disease who are grouped in GENEFA in collaboration with the Spanish Federation of Ataxias and the BabelFAmily. The Friedreich’s Ataxia Research Alliance (FARA), one of the main patients’ associations in the United States now joins the endeavour.

2) Frataxin delivery research project:

https://www.irbbarcelona.org/en/news/new-research-front-to-tackle-friedreichs-ataxia
The associations of patients and families Babel Family and the Asociación Granadina de la Ataxia de Friedreich (ASOGAF) channel 80,000 euros of their donations (50% from each organisation) into a new 18-month project at the Institute for Research in Biomedicine (IRB Barcelona). The project specifically aims to complete a step necessary in order to move towards a future frataxin replacement therapy for the brain, where the reduction of this protein causes the most damage in patients with Friedreich’s Ataxia.

The study is headed by Ernest Giralt, head of the Peptides and Proteins Lab, who has many years of experience and is a recognised expert in peptide chemistry and new systems of through which to delivery drugs to the brain, such as peptide shuttles—molecules that have the capacity to carry the drug across the barrier that surrounds and protects the brain. Since the lab started its relation with these patients’ associations in 2013*, it has been developing another two projects into Friedrich’s Ataxia.

 

 

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