DNA and RNA make muscle fibers...

Scientists have recently discovered that DNA and RNA make muscle fibers. I know what you are thinking, did you get your information from a biology textbook written in 1965? Well, you would be misinterpreting what I am saying. Scientists from Stanford University have recently been able to construct sliding filament models only with DNA and RNA interacting with actin instead of myosin heads.

Normally, a muscle contracts when myosin heads move actin with the expenditure of ATP. This is a one directional motion that consists of a contraction phase where the myofibril is shortened and the relaxation phase where the muscle cell passively relaxes.

Figure 1

The biomechanical motors use RNA arms to interact with actin filament as seen in figure 1. By creating a tetramer of RNA arms they have constructed a rotatory device that interacts with the actin filament shown in figure 2. With this device, they have created two separate biomechanical motors. The first contains a stationary RNA motor that moves the actin filament in and out much like a muscle fiber. I say in and out because by adding a set of two DNA constructed switches, they are able to reverse the direction of the tetramer motor allowing the motor to be bidirectional. This precedes the abilities of a normal muscle fiber. The RNA model can also be activated through ions or photons of light.

Figure 2

The second model involves a stationary actin filament and a mobile RNA tetramer that acts like a train car running along a track. This functions similar to kinesin moving along microtubules. The biomechanical motors can be set up to perform a multitude of different tasks simultaneously.

The practical applications for this are to one day provide prosthetics for damaged structures but on a cellular level.  Many structures in the body use biomechanical motors like muscle fibers and kinesin but also structures like cilia and even F1 ATPase. They also see practical applications in the transportation of molecular cargo. Ultimately they would like to genetically encode them into cells to allow them to perform intracellular tasks.

Figure 3

Currently, artificially created motors are far less efficient at converting chemical energy to mechanical energy and vice versa, but the hope is to one day precede or diversify the abilities of cellular motors. These motors have a long ways to go, but it is considered to be the most advanced engineered biomolecular motor currently created and can be the foundation for many technological advancements of the future.   

         

References

Biomolecular motors. (2005, December 07). Retrieved from http://www.sciencedirect.com/science/article/pii/S1369702105712864

Borman, S. (n.d.). Engineered myosin motor uses RNA arm to march on protein fibers. Retrieved from https://cen.acs.org/articles/95/i45/Engineered-myosin-motor-uses-RNA.html