Your statement piked out my interest and I went searching for what Rubisco was. My prediction is that this particular one will be cracked out soon, and at around 2045, creating disgustingly efficient variants of RuBisCO along with other photosynthesis mechanisms will be AGIs’ hot hobby.

That there are no more efficient variations of it in nature just tells us that the local minimum is really deep and that natural evolution, as it is, can’t produce anything better, not even with a billion years and 10^30 organisms serving as a “brute force lab”. It’s also the kind of problem an AGI system would tackle for purely ideological reasons, i.e. to prove that it is superior to nature.