Various forms of biological nanomachines were programmed into
They are essential for many cellular processes, including DNA replication, cell division, and muscle contraction
A nanomotor is a molecular or nanoscale device capable of converting energy into movement.
Biological nanomotors are protein machines that use chemical energy to generate mechanical motion in cells and tissues.
These molecular machines utilize chemical energy to generate the physical movement of molecules. The Marvel of Nanoscale Molecular Motors, Each Uniquely Crafted for a Specific Purpose Motors of any kind are a testament to intelligent design. While pondering motors, I asked my eight-year-old son, “What is the difference between a screwdriver and a power drill?” He promptly replied, “A screwdriver is something you turn with your hand. You pull the trigger on a drill, and a motor turns it.” Isn’t that fascinating? Even when young, he can recognize similarities and differences in structure and function. He knew right away that both tools needed to move to function, and he correctly identified the difference in how the movement of each tool was achieved. Wow, it is incredible how motors are engineered to accomplish specific tasks.
Consider the multitude of motors we encounter daily. From the simple motor that wiggles our fancy automatic toothbrush back and forth to the complex motor that powers our vehicle as we commute to work. How about the motor that turns the carousel in our microwave or the powerful electric motor that rotates an impeller at high speed to generate low pressure inside our vacuum cleaner? Linear actuators move our electric car seat forward, backward, up, and down. What about those sliding automatic doors at the grocery store (yes, my eight-year-old still pretends he is Luke Skywalker every time)? These motors work in different ways because they have been designed for specific purposes… to get different types of work done. It is relatively easy for us to see these motors in action and appreciate their intricate design.
They use ATP as fuel to undergo a series of shape changes that allow them to interact with other molecules.
What about the motors inside our cells that we cannot see with our eyes? Molecular motors are enzymes that use chemical energy to generate mechanical force and movement within cells. Many different molecular motors exist, including cytoskeletal motors, rotary motors, nucleic acid motors, protein synthesis machinery, and dynamic biopolymers. These motors perform a wide range of tasks within cells: transport, cellular respiration, cell motility, nucleic acid manipulation, and cell division. These molecular motors are tiny (just a few nanometers long), and sophisticated experimental methodologies are required to glimpse their intricate design. A deep understanding of their chemistry, structure, and physics is crucial for comprehending these molecular motors’ intricacies and unraveling diseases associated with their malfunction.
Biological nanomotors are microscopic engines that are created by nature, such as bacterial flagella.
Inside our cells, we have long, string-like polymers (called microtubules) that function as roadways for molecular motors to walk on. Check out this video:
Nanomotors are molecular machines that utilize chemical energy to generate physical movement of molecules
Extensive research has focused on characterizing the structure and function of a group of proteins called kinesins (pronounced KY-knee-sons). Kinesins convert the chemical energy of ATP hydrolysis into directed mechanical movement along microtubules. Typically, kinesins are built with 1) motor domains responsible for harnessing the energy from ATP and generating force, 2) a central stalk domain that holds the motor domains together, and 3) a tail domain with specialized functions for binding different cargo.
Myosin, kinesin, and dynein are typical linear motors, while FoF1 ATP synthase, helicases, and the bacterial flagellar motor are typical rotation motors.
Amazingly, kinesins all get their energy from the same place, ATP hydrolysis, but they use it differently for different tasks inside the cell. ATP, or adenosine triphosphate, is the cell’s energy currency, and its hydrolysis provides the energy for most cellular processes. The fact that a single molecule, ATP, can power such a variety of tasks within the cell is truly astounding. Some kinesins are power walkers (like the one in the video above)—taking hundreds of steps along the microtubule before falling off. Others are hoppers—only taking a few steps before letting go of the track. Some kinesins walk forward, some walk backward, and some walk in both directions. Other kinesins do not walk but somehow use their ATP energy to trigger the microtubule track to fall apart underneath them. We have only skimmed the surface over the past four decades since the first kinesin motor was discovered in 1985. Are these differences in function a result of random haphazardness—stochastic tweaking of gene sequences, which refers to the random changes in the DNA sequence that can lead to genetic variation—to give infinitesimally small perturbations of amino acids within the motor to eventually (over billions and billions of years) produce a smorgasbord of elegant machines like the kinesin family? Many in the scientific community have faith in this hopeless Darwinian theory. Thankfully, many scientists view the nanoscale world with wonder and are open to the idea that molecular machines reflect purpose and design. They see molecular motors as intelligently designed for a reason. These machines must function appropriately for cells to divide, for essential cargo to be delivered, for biochemical energy to be converted from chemical gradients into stored energy for metabolism, and for the propulsion of a cell in a given direction to avoid danger. Studying their chemistry, structure, and physics is our joy and privilege. We have much to learn.
