Tal­mu­dic Ques­tion #55

The Cen­tral Dogma of Mol­e­c­u­lar Bi­ol­ogy has never been se­ri­ously chal­lenged. Here is your chance: can you con­ceive of a mech­a­nism whereby ge­netic in­for­ma­tion can flow di­rectly from pro­teins to nu­cleic acids?

 

 

 

 

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16 years ago

A kind of chimera be­tween a chap­er­one, a ri­bo­some and a RNA-poly­merase. The chap­eron do­main will un­fold the pro­tein so the side chains of the amino acids could be recog­nised and read by the ri­bo­some do­main. In this part, each side chain will be aso­ci­ated with a set of spe­cific three bases. For ex­am­ple, leucine with its long hy­dro­car­bon chain will al­ways be aso­ci­ated with a cy­to­sine, uracil and cy­to­sine. There is not need for a de­gen­er­ate code this time be­cause we go from 20 to 64 amino acids. This is the tricky part, be­cause it is dif­fi­cult to imag­ine an ac­tive cen­ter that has the side chain and al­lows the en­trance and lo­ca­tion of nu­cleotides. Af­ter that, the poly­mer­iza­tion of nu­cleic acid oc­curs (I bet for RNA) thanks to the poly­merase do­main.
Be­cause it is an in­ver­sion of the proc­cess I pro­pose the name of chap­er­o­borimerase for this chimeric macro­mol­e­cule
By the way. Con­grat­u­la­tions for the re­cent prize.

Nathan Myers
16 years ago

Na­ture knows no dogma.
The sim­plest case would be a pro­tein that ex­cises a whole gene. If that's too crude, I find it easy enough to be­lieve in a pro­tein that rec­og­nizes a par­tic­u­lar se­quence, and sub­sti­tutes one base for an­other in a spec­i­fied po­si­tion, e.g. turn­ing FOXP2 from simian to hu­man form.
De­tails, please, on the prize?
Elio's re­ply. Plane ticket to Stock­holm is in the mail

16 years ago

This de­scrip­tion of "non-Dog­matic" in­for­ma­tion trans­fer re­minds me of all the great de­bates be­tween Crick and Gamov and the oth­ers about how cod­ing would work. But I do won­der if we are miss­ing things. The Cairns-Smith "life from clay" was one ap­proach:
http://en.wikipedia.org/wiki/Graham_Cairns-Smith
And so far as the deeply weird, how about "cor­ti­cal in­her­i­tance"? First de­scribed in pro­tists, it is far more wide­spread:
http://science.jrank.org/pages/48371/Cortical-Inheritance.html
Who knows what we are all miss­ing? Joshua Leder­berg used to won­der if we are so fix­ated on DNA/RNA based life that we might miss "shadow life" here on Earth! He used to sug­gest try­ing to grow or­gan­isms from an in­ocu­lum to which was added a huge amount of ra­dioac­tive phos­pho­rus. I don't know if any­one ever tried that!