Biological motors

Citation

Rudall, B.H. (1999), "Biological motors", Kybernetes, Vol. 28 No. 5. https://doi.org/10.1108/k.1999.06728eaa.007

Biological motors

Keywords Automation, Cybernetics, Research, Technological developments

Abstract Reports and surveys are given of selected current research and development in systems and cybernetics. They include: Language interface, Automated automobile, Innovative space technology, Software reliability and safety, Automatic analysis of handwritten documents, High-tech musical instruments, Biological motors, Interplay between smell and the mind, Cybernetics and automation.

Biological motors

Nano-mechanics brings new devices

An article in the UK's Guardian Newspaper's Science and Technology Supplement (Online, November 1998) by Michael Brooks, with the title "Nature's Motors" reminded us of the great progress being made in nanotechnology and of the work of non-profit making organisations such as the Foresight Institute. This Institute works towards the creation of machines based on those present in living organisms. They would be on a scale that might enable us to build tiny machines, such as robots, that could be assembled atom by atom to carry out a variety of functions. This is perhaps best illustrated by the advances in microsurgery inside the body that have been previously reported in these surveys and reports.

The biological context

What has biology to offer to nano-technology? Nature's motors are invariably small, yet powerful and above all efficient for the task to be performed. We are reminded in this article that in moving your eyes over this text for example, you are performing a task that is beyond the understanding of modern science. The simple movement of the muscles in the eye is still a mystery. It is suggested that inside the muscles tiny proteins called myosins are doing the work but we do not know how they accomplish it. This is taken as an example of a biological motor and we are told that the body contains billions of them that break up the chemicals that, as a whole, make us what we are.

The biological input to nano-mechanics then becomes apparent. Can we mimic human biology? We are told that living beings are collections of machines with functions that include those required for exertion and movement and those that are involved in almost everything that happens inside a living creature's body.

Block's research

Dr Steven Block of Princeton University, USA, is a molecular biologist who doubts some of the goals that have already been mentioned in this report, and does not consider them to be truly realistic. He has, however completed research into biological motors. His research team's studies have recently been published on RNA polymerase which is an enzyme which rips through DNA, separating its twin strands so that it can duplicate itself. This is of course of regarded as an essential part of life, that is that every cell relies on this process.

The Block team has found that the RNA polymerase is in effect a powerful motor. He describes it as being somewhat like a biological snowplough. It is a few millionths of a millimetre in size and is able to exert force equivalent to the weight of a red blood cell more than a thousand times its size. Dr Block says that: "exertion that separates DNA strands is fuelled by the DNA itself. It is as if you were laying down an asphalt road using the asphalt itself as a fuel".

As to how a biological motor could work, he says: "This is truly a fundamental question for which a good answer has not been developed. The more we study it the more mysteries and enigmas we come across".

The list quoted of examples of biological motor functions is very extensive. It would include, for example:

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  bacteria that use a rotary motor to twist tails for propulsion;

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  sperm cells - the start of life - use their motors to swim to an egg;

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  cell division after fertilisation involves motors to take chemicals from one place to another; and

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  hairs in the ear use motors to change their shape for optimum performance.

In Michael Brooks' report he says that: "One of the biggest surprises in biological motor research came with the discovery of the 'railway within': a molecular motor called kinesin pulls chemicals around a cell using tracks called microtubules". Block is reported to have taken a kinesin motor molecule, attached it to a micron-diameter plastic bead, and watched it pull the bead along microtubles fixed to a microscope slide. It is said that by holding the bead using "laser tweezers" - this is where the bead can be trapped in the brightest part of a laser beam - Block has carried out a tug of war with the kinesin motor to measure its capabilities. It has been stated that kinesin has the strength of myosin motors in muscles, but is five or six times weaker than RNA polymerase. Kinesin, it seems, is also able to travel around cells at around 800 nanometres a second, which is about 3mm per hour and 200 times faster than RNA polymerase.

Future studies

Obviously we require to understand a great deal more about these motors, particularly as research suggests that many diseases such as schizophrenia, anaemia etc. are linked to their breakdown or absence. The result is that many scientists are discussing how biological motors could be introduced into living organisms to cure such diseases. This we are told, is where gene therapy comes onto the scene.

Unlike many other scientists Block regards this research as fundamental science and not, it is emphasised by Brooks, either clinical medical science or a way of building tiny robots. Although Block apparently concedes that the Foresight Institute, and its founder Eric Drexler are probably right to look to biology, Blocker says of Drexler that:

He believes that if one is to think about building machines on the scale of proteins we have a lot to learn from the way that nature builds things. Whether we can recapitulate nature's way of building an artificial machine remains to be seen.

Readers have the opportunity to obtain more information about this research by visiting: http://www.molbio.princeton.edu/block/block.html; kinesin sites at: http://util.ucsf.edu/people/kull/kinesin.html; Foresight Institute at: www.foresight.org