ATP

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The Biological Motors That Power Our Bodies

October 14, 2024 by 50 Comments

Most of us will probably be able to recall at least vaguely that a molecule called ATP is essential for making our bodies move, but this molecule is only a small part of a much larger system. Although we usually aren’t aware of it, our bodies consist of a massive collection of biological motors and related structures, which enable our muscles to contract, nutrients and fluids to move around, and our cells to divide and prosper. Within the biochemical soup that makes up single- and multi-cellular lifeforms, it are these mechanisms that turn a gooey soup into something that can do much more than just gently slosh around in primordial puddles.

There are many similarities between a single-cell organism like a bacteria and eukaryotic multi-cellular organisms like us humans, but the transition to the latter requires significantly more complicated structures. An example for this are cilia, which together with motor proteins like myosin and kinesin form the foundations of our body’s basic functioning. Quite literally supporting all this is the cytoskeleton, which is a feature that our eukaryotic cells have in common with bacteria and archaea, except that eukaryotic cytoskeletons are significantly more complex.

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A cartoon of the Sun above a windmill and a solar panel with a lightning bolt going to a big grey gear with "AAAp" written on it. A small "e-" on a circle is next to it, indicating electricity transfer. Further to the right is an ADP molecule connected to a curved arrow going through the AAAp gear to turn into ATP. Three cartoon shapes, presumably illustrating biological processes are on the right with arrows pointing from the ATP.

Powering Biology With Batteries

July 21, 2024 by 18 Comments

We’ve all been there — you forgot your lunch, but there are AC outlets galore. Wouldn’t it be so much simpler if you could just plug in like your phone? Don’t try it yet, but biologists have taken us one step further to being able to fuel ourselves on those sweet, sweet electrons.

Using an “electrobiological module” of 3-4 enzymes, the amusingly named AAA (acid/aldehyde ATP) cycle regenerates ATP in biological systems directly from electricity. The process takes place at -0.6 V vs a standard hydrogen electrode (SHE), and is compatible with biological transcription/translation processes like “RNA and protein synthesis from DNA.”

The process isn’t dependent on any membranes to foul or more complicated sets of enzymes making it ideal for in vitro synthetic biology since you don’t have to worry about keeping as many components in an ideal environment. We’re particularly interested in how this might apply to DNA computing which we keep being promised will someday be the best thing since the transistor.

Maybe in the future we’ll all jack in instead of eating our daily food pill? If this all seems like something you’ve heard of before, but in reverse, maybe you’re thinking of microbial fuel cells.

Binding of the Rab5(GTP) to EEA1 triggers a transition of the EEA1 molecule from a rigid, extended state to a more flexible, collapsed state. (Credit: Anupam Singh et al., 2023)

Not Just ATP: Two-Component Molecular Motor Using GTPase Cycle Demonstrates Mechanotransduction

May 17, 2023 by 15 Comments

For most of us who haven’t entirely slept through biology classes, it’s probably no secret that ATP (adenosine triphosphate) is the compound which provides the energy needed for us to move our muscles and for our body to maintain and repair itself, yet less know is guanosine triphosphate (GTP). Up till now GTP was thought to be not used for mechanical action like molecular motors, but recent research by Anupam Singh and colleagues in Nature Physics (press release) has shown that two GTPase hydrolase enzymes (Rab5 and EEA1) function effectively as a reversible molecular motor.

Although much of the heavy lifting in the body has shifted to use ATP with ATPases such as myosin and kinesin, GTPases have retained their functional roles in mostly signal transduction (acting as switches or timers), a tethered EEA1 enzyme performs mechanical force when a Rab5 enzyme (in its activated, GTP state) binds to it. Within e.g. a cell this can pull membranes and other structures together. Most importantly, the researchers found that no external influence was necessary for the inactive (GDP) Rab5 enzyme to separate and EEA1 to revert back to its original state, completing a full cycle.

This discovery not only gives us another intriguing glimpse into the inner workings of biological systems, but also increases our understanding of how these molecular motors work, opening intriguing possibilities for constructing our own synthetic structures such as protein engines, where mechanical movement is needed on scales which require such molecular motors.

(Heading image: Binding of the Rab5(GTP) to EEA1 triggers a transition of the EEA1 molecule from a rigid, extended state to a more flexible, collapsed state. (Credit: Anupam Singh et al., 2023) )