24 February 2021

Rubisco, Evolution, and the implications of rational intervention in the future of life

 If you're unfamiliar with the most abundant enzyme on Earth, Rubisco, (upon which essentially all plant and animal life is totally dependent), you might wish to read this. For those who are curious about life, the universe and everything. What is truly amazing is that a long, LONG time ago, nature came up with an OK, but not great, way to fix carbon into the very stuff of life, but it was before there was a lot of oxygen in the atmosphere, so it's not quite good enough at distinguishing CO2 from Oxygen. But humans, whose adaptive intelligence is THE most significant development since the evolution of photosynthesis, are about to dramatically improve the efficiency of Rubisco, after 3½ billion years, by modifying its natural form to make it better at rejecting oxygen and latching on to CO2, which is its function.

I never learned this stuff in school...the importance, function, and name for Rubisco wasn't really understood until about 1980. But it is a truly fundamental aspect of life that everyone should know about in basic outline.
This passage near the end of the admittedly highly technical article is to me the most interesting.
"Even though evolution is generally considered to be a highly creative force, its nature is actually rather conservative. Once a biological solution is found by evolution, the space to explore new evolutionary paths dramatically narrows, as evolution rather tends to work in a tinkering fashion by improving and recombining existing parts and pieces. This pattern is also reflected in RubisCO's history: ....
"With the advent of synthetic biology, however, it becomes possible to realize completely novel biological solutions that are based on rational considerations and not bound by historical-evolutionary constraints. Currently, several ideas are followed to overcome RubisCO's inefficiency with synthetic biological methods: Some approaches aim at replaying the evolution of RubisCO with RubisCO variants [54] or resurrected ancestors [10•], which are placed under strong O2 selection to create alternate RubisCOs that could break the Pareto front of modern-day RubisCOs. ....
"The most radical approaches, however, aim at completely redesigning photosynthetic carbon metabolism. Some efforts aim at realizing a synthetic photorespiration that would allow for additional CO2 fixation and could cover up for RubisCO's side reaction with O2 [56]. ...
"Only the future will tell whether carbon fixation through an alternatively evolved RubisCO, a neo-RubisCO, or RubisCO-independent synthetic pathways will allow us to rewrite or even overwrite the chapter of RubisCO's evolution."
Implicit in this whole discussion is a concept I think is emerging and will become dominant in our civilization before too long. And that is that, whether you think of it teleologically or not, one function of the evolution of humanity is that evolution will become free of the conservatism mentioned in this passage, and truly novel solutions that will allow life to thrive and exist in ways it never has before, in environments far beyond earth in space and time, will come about, with the intervention of human intelligence as a critical factor in future evolution. A Brave New World, which I think will happen whether as individual humans we want it to or not. https://www.sciencedirect.com/science/article/pii/S095816691730099X

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