Nav: Home

Physics of life: Motor proteins and membrane dynamics

July 25, 2019

Motility is an essential property of many cell types, and is driven by molecular motors. A Ludwig-Maximilians-Universitaet (LMU)in M has now discovered that the motor protein myosin VI contributes directly to the deformation of the cell membrane, as required for locomotion or endocytosis.

Membranes composed of a lipid bilayer define the outer surface of nucleated cells (the plasma membrane) and delimit the vital organelles within these cells, such as mitochondria and nuclei. The membrane curvature determines the three-dimensional form of these structures, and is therefore a key factor in their respective functions. Furthermore, the ability to actively deform membranes is indispensable for many cellular processes. Using a combination of experimental and theoretical approaches, LMU research groups led by Prof. Claudia Veigel (Biomedical Center) and Prof. Erwin Frey (Arnold Sommerfeld Center for Theoretical Physics), who are also members of the Munich Center for Nanoscience (CeNS), have now demonstrated that proteins called molecular motors are directly involved in the control of membrane deformation. The new findings appear in the online journal Nature Communications.

Formation and dynamics of the membrane curvature is the result of a complex interplay between many different proteins, in which the cytoskeleton - with which molecular motors interact - plays a significant part. The motor interactions enable the cell's internal skeleton to be dynamically broken down locally, and reassembled into new configurations. These processes in turn indirectly exert forces onto the cytoplasmic membrane. The motor proteins move along the various filament systems, which together comprise the cytoskeleton, transporting molecular cargos to their destinations. However, the motor proteins themselves can also act as signaling molecules. "We have now discovered a completely new type of function for one particular motor protein, called myosin VI: this motor directly engages with the components of the plasma membrane and dynamically alters its shape," says Laeschkir Würthner, joint first author of the study.

"Using fluorescent markers and super-resolution fluorescence microscopy we were able to experimentally confirm that myosin VI binds directly to the membrane. Combining these experiments with triangular-shaped gold nano-particles we also found that this interaction occurs in a remarkably selective and highly cooperative fashion - specifically at locations where the membrane curvature adopts a saddle shape. The binding sites appear at nano-pores, which are induced by thermal fluctuations. When myosin VI molecules dock at these sites, they do so in a dynamically variable, flower-like pattern, which can reach diameters of several micrometers around each pore. In our experiments, the circumference of these 'flowers' grows at a constant rate, which is directly proportional to the concentration of myosin available," Veigel explains.

The authors of the study propose that this newly discovered function of myosin-based motors is involved in important cellular processes, such as endocytosis and the formation of membrane protrusions. "We have also developed a quantitative theoretical model, which correctly describes the protein-membrane interaction and the resulting dynamics of membrane morphology," says Frey. "We believe that, in the near future, our new assay and the model that underpins it will help us to uncover other mechanisms of membrane deformation, and elucidate the universal role of membrane curvature in cellular function."

Ludwig-Maximilians-Universität München

Related Proteins Articles:

Discovering, counting, cataloguing proteins
Scientists describe a well-defined mitochondrial proteome in baker's yeast.
Interrogating proteins
Scientists from the University of Bristol have designed a new protein structure, and are using it to understand how protein structures are stabilized.
Ancient proteins studied in detail
How did protein interactions arise and how have they developed?
What can we learn from dinosaur proteins?
Researchers recently confirmed it is possible to extract proteins from 80-million-year-old dinosaur bones.
Relocation of proteins with a new nanobody tool
Researchers at the Biozentrum of the University of Basel have developed a new method by which proteins can be transported to a new location in a cell.
Proteins that can take the heat
Ancient proteins may offer clues on how to engineer proteins that can withstand the high temperatures required in industrial applications, according to new research published in the Proceedings of the National Academy of Sciences.
Designer proteins fold DNA
Florian Praetorius and Professor Hendrik Dietz of the Technical University of Munich have developed a new method that can be used to construct custom hybrid structures using DNA and proteins.
The proteins that domesticated our genomes
EPFL scientists have carried out a genomic and evolutionary study of a large and enigmatic family of human proteins, to demonstrate that it is responsible for harnessing the millions of transposable elements in the human genome.
Rare proteins collapse earlier
Some organisms are able to survive in hot springs, while others can only live at mild temperatures because their proteins aren't able to withstand such extreme heat.
How proteins reshape cell membranes
Small 'bubbles' frequently form on membranes of cells and are taken up into their interior.

Related Proteins Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...