Wednesday, August 25, 2010

Mirror, mirror

Day 294
Day 294,
originally uploaded by JimmyMac210.

When I heard a while ago that a team of researchers had expanded the genetic code by altering the subcellular machinery used to synthesize proteins I thought this would be big all over the mainstream media. I was wrong, however, and I have heard nary a peep on how this could lead to all sorts of interesting mutant enzymes and bizarre polypeptides by substituting other things in place of the twenty-two amino acids that naturally occur on Earth.

I would like to propose a slightly different hack made possible with the expanded vocabulary: mirror image proteins. We could designate twenty-two of the four base pair sequences with mirror-reversed optical isomers of the standard amino acids, generate the appropriate mRNA sequence to assemble them in exactly the same way as proteins we already know, and have the ribosomes and tRNA machinery start to produce these backward polypeptides. I would guess that these would fold in exactly the same way as the conventional proteins, only reversed, with the left-handed alpha helices and other structural elements matching up just as they should. Going further, we could take the entire genome of an organism and rewrite it using our new four base pair language, provide it with the wrong-handed nutrients needed, and have it generate all the proteins making up that creature but completely reversed. It would take a little bit of work to engineer the mirror cells needed to house this machinery, but given enough time I am sure it could be done. We would start with microbes and work our way up to larger animals and plants once we had everything in place.

In the end, we would have a completely mirror-reversed organism relying on the alternate coding in order to grow and reproduce. If we were to eat that organism, we would not be able to digest it very well at all and so would be inherently low in calories. But just maybe it might taste wonderful.