biological motors otherwise motor proteins; molecular motors (rus. моторы, биологические otherwise моторные белки; биологические наномоторы; молекулярные моторы) — motor proteins and protein complexes that generate mechanical force to enable cell movement, intracellular transport and other biological processes.

Description

Biological motors include motor proteins, such as myosins, kinesins and dyneins that enable muscular contractions, cell motility and division, endocytosis, exocytosis and intracellular transport of organelles and macromolecules. The aforementioned motor proteins are the so-called linear motors that perform mechanical functions through moving in one direction along the cytoskeleton components – microfilaments (myosins) or microtubules (kinesins and dyneins).

For energy supply linear motors use adenosine triphosphate (ATP) – the energy currency of life. Motor proteins engaged in direct or inverse motion usually generate different forces. All motor proteins are controlled by cellular systems which activate and inhibit such proteins and support their interaction with the cargo they carry.

Bacteria have a rotary motor that resembles an electric motor, the so-called flagellar motor complex. This system rotates the flagellae and provides cell motility in liquid. Another rotary motor, ATP synthase, is present in all living organisms. In the cells of animals and plants, ATP synthase is integrated in the inner membrane of mitochondria - cellular power plants. It uses the electrochemical gradient of protons on the mitochondrial membrane to synthesise ATP. The activity of this motor is reversible, i.e. it can decompose ATP and use the energy to generate the proton gradient on the mitochondrial membrane.

Special motor proteins generate substantial mechanical forces and move along DNA. Such proteins include DNA and RNA polymerases that synthesise nucleic acids from a DNA matrix, topoisomerase that unwinds DNA strands, as well as protein and RNA-protein systems for packing a viral genome into capsid.

The table shows the mechanical parameters of some biological motors.

Biological motors have nanoscale sizes and are often much more efficient than macromotors created by humans. They are ecologically safe and biocompatible. While biological motors are proteins encoding by corresponding genes, they can be synthesised and designed to have the required properties using genetic engineering. Biomolecular motors are attractive to nanotechnology because today they are virtually the only existing nanomotors (artificial nanomotors are currently in the initial stage of development). A disadvantage of biological motors is the special environment required for their performance, i.e. liquid medium with a specific salt composition, temperature and pH. This is a major limitation for their use. But these requirements do not limit the use of biological motors in nanomedicine, for example, in the development of diagnostic labs-on-a chip, gene and drug delivery systems, bionanoelectromechanical systems (bioNEMS), etc. 

Illustrations



Author

  • Shirinsky Vladimir P.

Source

  1. Molecular Motors / Ed. by Schliwa, Manfred. — Weinheim: Wiley–VCH, 2002.-582 p.

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