Researchers at Columbia University, in collaboration with biologists in Baylor College of Medicine, have made a significant step in understanding and imaging protein synthesis, pinpointing exactly where and when cells produce new proteins.
Assistant Professor Wei Min's team developed a new technique to produce high-resolution imaging of newly synthesized proteins inside living cells. The findings were published in the July 9th issue of The Proceedings of the National Academy of Sciences (Volume 110; Issue 28).
Proteins carry out almost every crucial biological function. Synthesis of new proteins is a key step in gene expression and is a major process by which cells respond rapidly to environmental cues in physiological and pathological conditions, such as cancer, autism and oxidative stress. A cell's proteome (i.e., the sum of all the cell's proteins) is highly dynamic and tightly regulated by both protein synthesis and disposal to maintain homeostasis and ensure normal functioning of the body. Many intricate biological processes, such as cell growth, differentiation and diseases, involve new protein synthesis at a specific location and time.
In particular, long-lasting neuronal plasticity (changes in neural pathways and synapses that come from alterations in behavior, environment and bodily injury), such as those underlying learning and long-term memory, require new protein synthesis in a site- and time- dependent manner inside neurons.
Min and colleagues' new technique harnesses deuterium (a heavier cousin of the normal hydrogen atom), which was first discovered by Harold Urey in 1932, also at Columbia University. When hydrogen is replaced by deuterium, the biochemical activities of amino acids change very little. When added to growth media for culturing cells, these deuterium-labeled amino acids are incorporated by the natural cell machineries as the necessary building blocks for new protein production. Hence, only newly synthesized proteins by living cells will carry the special deuterium atoms connected to carbon atoms. The carbon-deuterium bonds vibrate at a distinct frequency, different from almost all natural chemical bonds existing inside cells.
The Columbia team utilized an emerging technique called stimulated Raman scattering (SRS) microscopy to target the unique vibrational motion of carbon-deuterium bonds carried by the newly synthesized proteins. They found that by quickly scanning a focused laser spot across the sample, point-by-point, SRS microscopy is capable of delivering location-dependent concentration maps of carbon-deuterium bonds inside living cells.
"Incorporation of deuterium-labeled amino acids to new proteins is minimally disruptive, and their biochemical properties are almost identical to their natural counterparts," says Lu Wei, the lead author of the paper. "Our technique is highly sensitive, specific, and compatible with living systems under physiological conditions that don't require killing cells or staining."
Prior to this discovery, the ability to observe protein synthesis in living cells had eluded scientists, who devoted extensive efforts to achieving this goal. A classic strategy that involves labeling amino acids with radioisotopes to trace and quantify proteome dynamics requires the samples be killed and exposed to films. Fluorescence microscopy, another popular method, takes advantage of the inherent glowing of green fluorescent protein (GFP) to follow a protein. While this process does work on individual proteins, scientists can't observe the cell's entire proteome. A third technique, bioorthogonal noncanonical amino acid tagging (BONCAT) metabolically incorporates unnatural (biosynthetic) amino acids containing reactive chemical groups. However, the method generally requires killing cells and subsequent dye staining, a process that presents an issue for live tissues and animals. Therefore, it is extremely challenging and desirable to quantitatively image proteome synthesis in living cells, tissues and animals with high resolution. Min's research opens the door for a new method to study living cells, presenting opportunities to understand previously unanswered questions about the behavior of cells as they perform their functions.
The next step for Min's team is to capture where and when a new protein is produced inside brain tissues when an animal is subject to various lab exercises to form long-term memory. "Our new technique will greatly facilitate understanding the molecular mechanisms of many complex behaviors such as learning and diseases," he says.
Beth Kwon | Source: EurekAlert!
Further information: www.columbia.edu
Further Reports about: amino acid > biological process > brain tissue > building block > carbon atom > chemical bond > individual protein > living cell > long-term memory > molecular mechanism > protein synthesis > SRS
More articles from Life Sciences:
Molecular snapshot of the plant immune system’s signal box
11.12.2013 | Max Planck Institute for Plant Breeding Research, Köln
Successful Teamwork: Unusual fungal metabolites with antitumor activity discovered by crowdsourcing
11.12.2013 | Angewandte Chemie International Edition
The molecular architecture of three key proteins and their complexes reveals how plants fine-tune their immune response to pathogens
Plants rarely get sick in their natural environment. When the threat of infection arises, a quick decision is made about the necessary countermeasures. The course is set by a protein which forms complexes with its partner proteins for this purpose.
Jane Parker from the Max Planck Institute for Plant Breeding ...
Researchers studying speciation of butterfly orchids on the Azores have been startled to discover that the answer to a long-debated question "Do the islands support one species or two species?" is actually "three species".
Hochstetter's Butterfly-orchid, newly recognized following application of a battery of scientific techniques and reveling in a complex taxonomic history worthy of Sherlock Holmes, is arguably Europe's rarest orchid species. Under threat in its mountain-top retreat, the orchid urgently requires conservation recognition.
A lavishly illustrated publication, titled "Systematic revision of Platanthera in ...
Researchers from Brown University and the University of Hawaii have found some mineralogical surprises in the Moon's largest impact crater.
Data from the Moon Mineralogy Mapper that flew aboard India's Chandrayaan-1 lunar orbiter shows a diverse mineralogy in the subsurface of the giant South Pole Aitken basin.
The differing mineral signatures could be reflective of the minerals dredged up at the time of the giant impact 4 billion years ago, ...
In power electronics systems bonded connections create the central electrical connections between adjoining surfaces.
The quality of these bonded connections is one of the main factors that determines the reliability and availability of drive systems in electric vehicles, and hence constitutes a major design challenge for German auto manufacturers aiming to electrify their vehicles.
Now the partners participating in the RoBE (Robust Bonds in ...
International team of scientists develops new feedback method for optimizing the laser pulse shapes used in the control of chemical reactions
In many ways, traditional chemical synthesis is similar to cooking. To alter the final product, you can change the ingredients or their ratio, change the method of mixing ingredients, or change the temperature or pressure of the environment of the ingredients.
Like an accomplished chef, chemists have become very skilled ...
11.12.2013 | Information Technology
11.12.2013 | Life Sciences
11.12.2013 | Agricultural and Forestry Science
11.12.2013 | Event News
10.12.2013 | Event News
05.12.2013 | Event News