Do all ribosomes adhere to a single genetic code?

[bascule]

In Surely You're Joking, Mr. Feynman, Feynman talks about his brief stint as a biologist. One of the experiments he helped perform was transplanting ribosomes from mice into bacteria and seeing if they would work in place of the bacteria's own ribosomes. Unfortunately, Feynman had contaminated the ribosomes so the experiment failed, however he claimed other scientists would go on to discover that the way ribosomes map tri-nucleotide codons to peptides is universal for all forms of life, i.e. there is a single universal genetic code shared between all life on earth.

 

Wikipedia claims:

 

http://en.wikipedia.org/wiki/Ribosome

 

Ribosomes from bacteria, archaea and eukaryotes (the three domains of life on Earth), have significantly different structure and RNA.

 

Wikipedia also provides this table of codon to peptide mappings:

 

http://en.wikipedia.org/wiki/Genetic_code#RNA_codon_table

 

Does this just mean that ribosomes are structured differently between different domains of life, but still share the same code and perform the same function?

[GDG]

In Surely You're Joking, Mr. Feynman, Feynman talks about his brief stint as a biologist. One of the experiments he helped perform was transplanting ribosomes from mice into bacteria and seeing if they would work in place of the bacteria's own ribosomes. Unfortunately, Feynman had contaminated the ribosomes so the experiment failed, however he claimed other scientists would go on to discover that the way ribosomes map tri-nucleotide codons to peptides is universal for all forms of life, i.e. there is a single universal genetic code shared between all life on earth.

 

Wikipedia claims:

 

http://en.wikipedia.org/wiki/Ribosome

 

 

 

Wikipedia also provides this table of codon to peptide mappings:

 

http://en.wikipedia.org/wiki/Genetic_code#RNA_codon_table

 

Does this just mean that ribosomes are structured differently between different domains of life, but still share the same code and perform the same function?

 

Yes, there are different forms of ribosome: at least bacteria and eukaryotes have ribosomes of different sizes, and our mitochondrial ribosomes more closely resemble bacterial ribosomes.

 

However, the ribosome is not what enforces the genetic code: nothing in the ribosome specifies a particular nucleotide or a particular amino acid. The code is really determined by the aminoacyl-t-rna synthases, which are the enzymes that recognize a particular anticodon on a tRNA, and charge the other end of the tRNA with the appropriate corresponding amino acid.

 

There are a few idiosyncratic differences in genetic code in a few different species (see, e.g., Wikipedia), but these are pretty rare (apart from mitochondria, which have a slightly different code).

[bascule]

So the question remains can you transplant ribosomes from one domain of life to another and have them function properly? That's what Feynman implied.

[CharonY]

Essentially no. Some of the details between eu- and prokaryotic translation intitiation are different, requiring additional factors in eukaryotes. A simple transplantation of the ribosomes alone would thus render them dysfunctional. And as mentioned by GDG the code itself is essentially not ribsomally enforced.