New study finds two amino acids are the Marie Kondo of molecular liquid phase separation

September 15, 2020

NEW YORK, Sept. 15, 2020 - The last several years have brought mounting evidence that the molecules inside our cells can self-organize into liquid droplets that merge and separate like oil in water in order to facilitate various cellular activities. Now, a team of biologists at the Advanced Science Research Center at The Graduate Center, CUNY (CUNY ASRC) have identified unique roles for the amino acids arginine and lysine in contributing to liquid phase properties and their regulation. Their findings are available today online in Nature Communications.

Known as liquid-liquid phase separation, the process allows some molecules within a cell to cloister themselves into membraneless organelles in order to carry out certain duties without interruption from other molecules. The mechanism can also allow molecules to create multiphase droplets that resemble, say, a drop of honey inside a drop of oil surrounded by water in order to carry out sophisticated jobs.

"This is a really exciting new research area because it uncovers a core biological function that, when gone awry, may be at the root of disease, particularly neurodegeneration as in ALS or Alzheimer's," said principal investigator and Graduate Center, CUNY Biochemistry Professor Shana Elbaum-Garfinkle, whose lab at the CUNY ASRC Structural Biology Initiative conducted the study. "With an understanding of how individual amino acids contribute to phase behavior, we can begin to investigate what's going wrong in liquid phase separation that may interfere with normal biological function and potentially design therapies that can modulate the process."

Researchers have suspected for a while that arginine and lysine -- two of the 20 amino acids that make up all proteins -- were responsible for regulating liquid phase separation, but they weren't certain how each contributed to phase behavior and to creating the differing viscosities that cloister molecules into separate communities.

"Arginine and lysine are very similar amino acids in terms of both being positively charged, but they differ in terms of binding capability. We were really curious to understand what effect this difference would have on the material properties, such as viscosity or fluidity, of the droplets they form," said Rachel Fisher, the paper's first author and a postdoc in Elbaum-Garfinkle's lab. "We also wanted to know how these differences manifest themselves when the arginine and lysine systems are combined. Will the droplets coexist? When we saw they did, we then wanted to understand how we could modulate this multi-phase behavior."

To answer their questions, Elbaum-Garfinkle's team used a technique called microrheology -- whereby tiny tracers are used to probe material structures -- to track and investigate the properties of arginine and lysine droplets. They found that arginine-rich droplets were over 100 times more viscous than lysine-rich droplets, comparable to the difference between a thick syrup or ketchup and oil. The viscosity differences are significant enough that if lysine and arginine polymers are combined, they don't mix. Instead, they create multi-phase droplets that sit within one another like Dutch nesting dolls. Additionally, arginine has such strong binding properties that under some conditions it can compete with lysine and replace or dissolve lysine droplets. The researchers further identified ways to tune the balance between competition and coexistence of the two phases. The results present a novel mechanism for designing, controlling or intervening in molecular liquid phases.
-end-
This study was funded by the National Institute of Neurological Disorders.

About the Advanced Science Research Center

The ASRC at The Graduate Center elevates scientific research and education at CUNY and beyond through initiatives in five distinctive, but increasingly interconnected disciplines: environmental sciences, nanoscience, neuroscience, photonics, and structural biology. The ASRC promotes a collaborative, interdisciplinary research culture with renowned researchers from each of the initiatives working side-by-side in the ASRC's core facilities, sharing equipment that is among the most advanced available.

About The Graduate Center of The City University of New York

The Graduate Center of The City University of New York (CUNY) is a leader in public graduate education devoted to enhancing the public good through pioneering research, serious learning, and reasoned debate. The Graduate Center offers ambitious students more than 40 doctoral and master's programs of the highest caliber, taught by top faculty from throughout CUNY -- the nation's largest public urban university. Through its nearly 40 centers, institutes, and initiatives, including its Advanced Science Research Center (ASRC), The Graduate Center influences public policy and discourse and shapes innovation. The Graduate Center's extensive public programs make it a home for culture and conversation.

Advanced Science Research Center, GC/CUNY

Related Amino Acids Articles from Brightsurf:

Igniting the synthetic transport of amino acids in living cells
Researchers from ICIQ's Ballester group and IRBBarcelona's Palacín group have published a paper in Chem showing how a synthetic carrier calix[4]pyrrole cavitand can transport amino acids across liposome and cell membranes bringing future therapies a step closer.

Microwaves are useful to combine amino acids with hetero-steroids
Aza-steroids are important class of compounds because of their numerous biological activities.

New study finds two amino acids are the Marie Kondo of molecular liquid phase separation
a team of biologists at the Advanced Science Research Center at The Graduate Center, CUNY (CUNY ASRC) have identified unique roles for the amino acids arginine and lysine in contributing to molecule liquid phase properties and their regulation.

Prediction of protein disorder from amino acid sequence
Structural disorder is vital for proteins' function in diverse biological processes.

A natural amino acid could be a novel treatment for polyglutamine diseases
Researchers from Osaka University, National Center of Neurology and Psychiatry, and Niigata University identified the amino acid arginine as a potential disease-modifying drug for polyglutamine diseases, including familial spinocerebellar ataxia and Huntington disease.

Alzheimer's: Can an amino acid help to restore memories?
Scientists at the Laboratoire des Maladies Neurodégénératives (CNRS/CEA/Université Paris-Saclay) and the Neurocentre Magendie (INSERM/Université de Bordeaux) have just shown that a metabolic pathway plays a determining role in Alzheimer's disease's memory problems.

New study indicates amino acid may be useful in treating ALS
A naturally occurring amino acid is gaining attention as a possible treatment for ALS following a new study published in the Journal of Neuropathology & Experimental Neurology.

Breaking up amino acids with radiation
A new experimental and theoretical study published in EPJ D has shown how the ions formed when electrons collide with one amino acid, glutamine, differ according to the energy of the colliding electrons.

To make amino acids, just add electricity
By finding the right combination of abundantly available starting materials and catalyst, Kyushu University researchers were able to synthesize amino acids with high efficiency through a reaction driven by electricity.

Nanopores can identify the amino acids in proteins, the first step to sequencing
While DNA sequencing is a useful tool for determining what's going on in a cell or a person's body, it only tells part of the story.

Read More: Amino Acids News and Amino Acids Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.