F Rosa Rubicondior: Unintelligent Designer News - Compensating for the Designer's RuBisCo Blunder

Monday 16 August 2021

Unintelligent Designer News - Compensating for the Designer's RuBisCo Blunder

So much greenery as RuBisCo makes up in quantity what it lacks in quality - but it's still not enough to feed 9 billion people (by 2050).
Scientists take step to improve crops’ photosynthesis, yields | Cornell Chronicle

The world is heading for a severe food shortage as we approach a projected 9 billion people by 2050 (assuming global warming doesn't get us first!). To feed that number of people, farmers need to increase crop yields by some 50%. But there is a major road-block to achieving anything like that productivity from plants, because the entire system, indeed the entire cycle of life on Earth (save for a few chemosynthetic bacteria) is dependent on what must rate as the worst pieces of 'design' in all biology - RuBisCo.

RuBisCo, or to give it its full chemical name, ribulose-1,5-bisphosphate carboxylase/oxygenase, would be a major embarrassment to intelligent [sic] design advocates if they had the knowledge and intellect to understand it. It is responsible for taking 6 molecules of inorganic carbon dioxide (CO2) and 6 molecules of water (H2O) and, using just the energy in sunlight, making a molecule of glucose (C6H12O6) which is then used as the energy source and as the basic building block for many structural and storage carbohydrates such as cellulose, lignin (wood) starch, glycogen, etc. This forms the very basis of almost all food chains. It also, in the process, makes 6 molecules of oxygen (O2) as a waste product.

Incidentally, note that 'living' (organic) glucose molecules are made out of non-living (inorganic) molecules, and all without the involvement of god magic!

The problem is, RuBisCo is notoriously bad at what it does. Not only is it highly inefficient as catalysing enzymes go, catalysing only about four reactions a second as opposed to the hundreds or thousands of reactions a second for most enzymes, but it finds it hard to tell CO2 from molecular oxygen (O2) which, when RuBisCo tries to 'fix' it, produces a toxic product that stops RuBisCo working and wastes energy.

To anyone familiar with the way evolution works, this is easy to understand because the process of photosynthesis arose when the atmosphere on Earth contained little or no oxygen and, no matter how inefficient it was, the ability to 'fix' abundant CO2 and turn it into something as useful as glucose gave an enormous advantage to those organisms that could do it. The result was the first great toxic waste disaster as these organisms contaminated the atmosphere with their waste product - lots of the (then) toxic molecular oxygen. A side effect of this was that the iron dissolved in the world's oceans oxidized and precipitated out to form a layer of iron oxide in the geological column.

The survivors of the resulting mass extinction were those organisms (and there were only single-celled organisms in those times) that could use the oxygen to 'burn' glucose and release the energy stored in it to power their own metabolism. The problem was that living organisms quickly became dependent on this hugely inefficient RuBisCo molecule and still are. This is the reason there is so much green in the world, as plants need enormous quantities of the stuff, along with the associated green chlorophyll pigment, making up in quantity what it lacks in quality, to power their photosynthesis to produce enough glucose.

They do it via endosymbiotic organisms, derived from those early photosynthesising organisms, in the form of chloroplasts incorporated into their cells - complete with all their inefficiency.

To an ID Creationist, this explanation is not allowed by dogma so they have to credit this ludicrously complex and highly inefficient system to their beloved invisible magic friend as an example of a 'design' of which any real intelligent designer would be ashamed. But anyway, that's a problem for Creationist frauds to explain to their credulous dupes if ever any of them ever find the courage to learn about it and ask the obvious questions.

Fortunately, we now have scientists to intelligently design something better, using science, not magic.

What the team from Cornell University are trying to emulate is the evolved way that some cyanobacteria partially overcome the problem with a twofold approach. Firstly, they isolate the mechanism from atmospheric O2 inside a 'carboxysome' and secondly, they concentrate the carbon dioxide in the carboxysomes so RuBisCo has more of it to work with. The trick should simply be a matter of inserting these cyanobacterial carboxysomes into our crops, just as you might expect a real intelligent designer who supposedly came up with carboxysomes to have done, but of course, evolution can't do what an intelligent entity would do and use one solution evolved in one line for a different line altogether. The evolutionary process has no mechanism, appart from the rare examples of horizontal gene transfer, of jumping a solution to a problem from one branch of the evolutionary tree to another. If the process were controlled by an intelligent designer, however, that should be well within its capabilities.

However, it is not that simple either, as normal plants contain an enzyme called carbonic anhydrase whose job is to maintain a balance between the CO2 in the cell and sodium bicarbonate by catalysing the creation of bicarbonate from CO2 and water and also reversing that process as the dynamics change. And this would prevent the carboxysomes from concentrating the CO2 at high enough levels. The cell would just end up with lots of bicarbonate.
So what the scientists have done is a feasibility study involving the removal of carbonic anhydrase. As they report in their paper published in Proceedings of the National Academy of Sciences (PNAS), they found that plants won't grow properly if you remove all the carbonic anhydrase but that growth can be restored if the crops are grown in a chamber containing a high level of CO2, which results in the spontaneous creation of bicarbonate. Obviously, it would not be possible to grow all the crops needed in special chambers, but what they can do is engineer the crops to contain a CO2 transporter molecule in their cell membrane, so they can now grow normally without the damaging presence of carbonic anhydrase! What the research has shown is that the absence of carbonic anhydrase is not, in itself, fatal, even though bicarbonate is needed for normal cell metabolism.
And that is where real intelligence trumps the unintelligent, utilitarian process of evolution by natural selection, and how we can tell that neither our food crops, nor the process of photosynthesis with its ludicrously inefficient RuBisCo, were intelligently designed.

Sadly, the full paper is behind an expensive paywall, but the abstract is available here. Also available is a Cornell University news release announcing the publication of the paper and explaining the background to the problem and the research.

In their Abstract the team explain the significance of their work as:

Carbonic anhydrase enzymes located in chloroplast stroma have been hypothesized to facilitate photosynthesis in C3 plants because they catalyze a reaction involving bicarbonate and CO2, a substrate of the carbon-fixing enzyme RuBisCO. To test this possibility, tobacco mutants completely lacking chloroplast stromal carbonic anhydrase activity were produced by CRISPR/Cas9 mutagenesis. The plants displayed normal photosystem II activity and CO2 assimilation but also abnormal development and increased reactive oxygen species and stromal pH. We conclude that chloroplast carbonic anhydrase does not play a direct role in providing CO2 for carbon fixation. Instead, as is also true in microorganisms, carbonic anhydrase is necessary to supply bicarbonate for biosynthetic processes.
The question though is whether people will be willing to eat food crops that have been genetically engineered to contain the genes of cyanobacteria, even though we know exactly what those genes do, and more importantly, don't do, and that our food supplies depend on it.

But all these scientists are doing really is a modern and quicker version of what humans have been doing now for thousands of years, ever since we domesticated our first animals and plants and began breeding from the best to create the next generation - improving on what Creationism's putative magic designer designed for us, because it wasn't up to the required standard and needed considerable improvement.
If you wish to know more about RuBisCo and why it is such a problem for ID advocates, I devote a section of my popular book, The Unintelligent Designer: Refuting the Intelligent Design Hoax to the subject.

Thank you for sharing!

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