Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 
Datenbankrecherche:

 

Pinpointing Protein Locations

13.02.2013
An innovative technique which pinpoints protein locations and helps researchers unravel the protein's functions has been developed by the researchers from the Massachusetts Institute of Technology (MIT), researchers who recently moved from MIT to the Ulsan National Institute of Science (UNIST) explain.
Scientist from MIT have now developed a technique that can tag all of the proteins in a particular region of a cell, allowing them to more accurately map those proteins.

“There was no previous high-quality map of the matrix subdomain of mitochondria, and now we have one” said Alice Ting, the Ellen Swallow Richards Associate Professor of Chemistry at MIT. “We’re still really far from that goal, but the overarching motivation is to get closer to that goal.”

Diagram of a mitochondrion

This innovative technique combines the strengths of two existing techniques — microscopic imaging and mass spectrometry — to map proteins in a specific cell location and generate a comprehensive list of all the proteins in that area.

In a paper appearing in the Jan. 31 online edition of Science, Rhee and colleagues used the new technique to identify nearly 500 proteins located in the mitochondrial matrix — the innermost compartment found in mitochondria, which can be thought of as the power houses of the cell where energy is generated. Previous attempts to map the entire set of proteins in the matrix (proteome) yielded a list of only 37 proteins.

Protein labeling

Using fluorescence or electron microscopy, scientists can determine protein locations with high resolution, but only a handful of a cell’s ~20,000 proteins can be imaged at once. “It’s a bandwidth problem,” Ting says. “You certainly couldn’t image all the proteins in the proteome at once in a single cell, because there’s no way to spectrally separate that many channels of information.”

With mass spectrometry, which uses ionization to detect the mass and chemical structure of a compound, scientists can analyze a cell’s entire complement of proteins in a single experiment. However, the process requires dissolving the cell membrane to release a cell’s contents, which jumbles all of the proteins together. By purifying the mixture and extracting specific organelles, it is then possible to figure out which proteins were in those organelles, but the process is messy and often unreliable.
The new MIT approach tags proteins within living cells before mass spectrometry is done, allowing spatial information to be captured before the cell is broken apart. This information is then reconstructed during analysis by noting which proteins carry the location tag.

The new system makes use of a chemical tag that includes biotin, one of the B vitamins. To label proteins with biotin, the researchers first designed a new enzyme they dubbed APEX. This enzyme is a *peroxidase*, meaning that it removes an electron and a proton in a reaction known as oxidation.
“What you do is tag the proteins with biotin while the cell is still alive, and then you just pull out those proteins,” Ting says. “Therefore you bypass all of the problems that are associated with trying to purify regions of cells and organelles, because you don’t have to anymore.”

A comprehensive list

To demonstrate the technique’s power, the researchers created a comprehensive list of the proteins found in the mitochondrial matrix. Most of a cell’s energy generation takes place in mitochondria, as well as many biosynthetic processes.
Using the new method, the team increased the number of proteins known to be located in the mitochondrial matrix. “There was no previous high-quality map of the matrix subdomain of mitochondria, and now we have one,” says Ting, adding that this new wealth of information should help biologists to learn more about the functions of many of those proteins.

Already, the team has found that an enzyme called ppox — involved in synthesizing heme, the iron-porphyrin complex found in hemoglobin — is not located where biologists had thought it was. As heme precursors move through the biosynthetic pathway, they are shuttled to different parts of the cell. Finding that ppox is in the matrix means that there must be unknown transporter proteins bringing heme precursors into the matrix, Ting says.

The researchers are now investigating proteins found in another compartment of the mitochondria, the intermembrane space. They are also modifying the chemistry of the labeling system so they can use it for other tasks such as mapping the topology of membrane proteins and detecting specific protein-protein interactions.

The lead scientists of this research are Hyun-Woo Rhee (former MIT postdoc, currently Assistant Professor, School of Nano-Bioscience and Chemical Engineering, UNIST) and Peng Zou, who received a PhD from MIT in 2012.

REFERENCE:

Hyun-Woo Rhee, Peng Zou, Namrata D. Udeshi, Jeffrey D. Martell, Vamsi K. Mootha, Steven A. Carr, and Alice Y. Ting. 2013. Proteomic Mapping of Mitochondria in Living Cells via Spatially Restricted Enzymatic Tagging. Science 1230593. Published online 31 January 2013 [DOI:10.1126/science.1230593]
Journal information
ScienceXpress

Eunhee Song | Research asia research news
Further information:
http://www.unist.ac.kr
http://www.researchsea.com

More articles from Life Sciences:

nachricht Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Mit solaren Gebäudehüllen Architektur gestalten

Solarthermie ist in der breiten Öffentlichkeit derzeit durch dunkelblaue, rechteckige Kollektoren auf Hausdächern besetzt. Für ästhetisch hochwertige Architektur werden Technologien benötigt, die dem Architekten mehr Gestaltungsspielraum für Niedrigst- und Plusenergiegebäude geben. Im Projekt »ArKol« entwickeln Forscher des Fraunhofer ISE gemeinsam mit Partnern aktuell zwei Fassadenkollektoren für solare Wärmeerzeugung, die ein hohes Maß an Designflexibilität erlauben: einen Streifenkollektor für opake sowie eine solarthermische Jalousie für transparente Fassadenanteile. Der aktuelle Stand der beiden Entwicklungen wird auf der BAU 2017 vorgestellt.

Im Projekt »ArKol – Entwicklung von architektonisch hoch integrierten Fassadekollektoren mit Heat Pipes« entwickelt das Fraunhofer ISE gemeinsam mit Partnern...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: Mit Bindfaden und Schere - die Chromosomenverteilung in der Meiose

Was einmal fest verbunden war sollte nicht getrennt werden? Nicht so in der Meiose, der Zellteilung in der Gameten, Spermien und Eizellen entstehen. Am Anfang der Meiose hält der ringförmige Proteinkomplex Kohäsin die Chromosomenstränge, auf denen die Bauanleitung des Körpers gespeichert ist, zusammen wie ein Bindfaden. Damit am Ende jede Eizelle und jedes Spermium nur einen Chromosomensatz erhält, müssen die Bindfäden aufgeschnitten werden. Forscher vom Max-Planck-Institut für Biochemie zeigen in der Bäckerhefe wie ein auch im Menschen vorkommendes Kinase-Enzym das Aufschneiden der Kohäsinringe kontrolliert und mit dem Austritt aus der Meiose und der Gametenbildung koordiniert.

Warum sehen Kinder eigentlich ihren Eltern ähnlich? Die meisten Zellen unseres Körpers sind diploid, d.h. sie besitzen zwei Kopien von jedem Chromosom – eine...

Im Focus: Der Klang des Ozeans

Umfassende Langzeitstudie zur Geräuschkulisse im Südpolarmeer veröffentlicht

Fast drei Jahre lang haben AWI-Wissenschaftler mit Unterwasser-Mikrofonen in das Südpolarmeer hineingehorcht und einen „Chor“ aus Walen und Robben vernommen....

Im Focus: Wie man eine 80t schwere Betonschale aufbläst

An der TU Wien wurde eine Alternative zu teuren und aufwendigen Schalungen für Kuppelbauten entwickelt, die nun in einem Testbauwerk für die ÖBB-Infrastruktur umgesetzt wird.

Die Schalung für Kuppelbauten aus Beton ist normalerweise aufwändig und teuer. Eine mögliche kostengünstige und ressourcenschonende Alternative bietet die an...

Alle Focus-News des Innovations-reports >>>

Anzeige

Anzeige

IHR
JOB & KARRIERE
SERVICE
im innovations-report
in Kooperation mit academics
Veranstaltungen

Aquakulturen und Fangquoten – was hilft gegen Überfischung?

16.01.2017 | Veranstaltungen

14. BF21-Jahrestagung „Mobilität & Kfz-Versicherung im Fokus“

12.01.2017 | Veranstaltungen

Leipziger Biogas-Fachgespräch lädt zum "Branchengespräch Biogas2020+" nach Nossen

11.01.2017 | Veranstaltungen

 
VideoLinks
B2B-VideoLinks
Weitere VideoLinks >>>
Aktuelle Beiträge

Weltweit erste Solarstraße in Frankreich eingeweiht

16.01.2017 | Energie und Elektrotechnik

Proteinforschung: Der Computer als Mikroskop

16.01.2017 | Biowissenschaften Chemie

Vermeintlich junger Stern entpuppt sich als galaktischer Greis

16.01.2017 | Physik Astronomie