To have functional messenger RNA translation: What is required?
One of the principal molecular nano factories required to give life a first go is the Ribosome which translates the digital information in messenger RNA into the amino acid alphabet, the analog information which polymerizes amino acids to produce proteins, information enriched polymers. But there is an entire armada of proteins and ribozymes required for this central process. I will list what is required, here.
Comparative genomic reconstructions of the gene repertoire of LUCA(S) point to a complex translation system that includes at least 18 of the 20 aminoacyl-tRNA synthetases (aaRS), several translation factors, at least 40 ribosomal proteins, and several enzymes involved in rRNA and tRNA modification. It appears that the core of the translation system was already fully shaped in LUCA(S) (Anantharaman, et al., 2002).
Koonin, the logic of chance, page 376
Breaking the evolution of the translation system into incremental steps, each associated with a biologically plausible selective advantage is extremely difficult even within a speculative scheme let alone experimentally.
Messenger RNA
Messenger RNA (mRNA) is a single-stranded RNA molecule that corresponds to the genetic sequence of a gene and is read by the ribosome in the process of producing a protein. Non-eukaryotic mRNA is, in essence, mature upon transcription and requires no processing, except in rare cases. Eukaryotic pre-mRNA requires several processing steps before its transport to the cytoplasm and its translation by the ribosome. That includes Splicing, 5' cap addition, Editing, Polyadenylation, Transport, mRNAs must be exported from the nucleus to the cytoplasm—a process regulated by different signaling pathways. 1 RNA repair has now been demonstrated to be a genuine biological process and appears to be present in all three domains of life. As with DNA, RNA can be damaged as well as incorrectly copied. The cell checks that an mRNA is correctly synthesized and deals with incorrectly copied RNAs through quality control. In both eukaryotes and bacteria, there are mechanisms for eliminating transcripts that fail to pass quality control. Without proofreading and repair, the number of mRNAs carrying coding errors could be significant.
The Ribosome
All cells use homologous ribosomes that consist of three universally conserved RNA molecules and some 50 proteins, of which about 20 are universally conserved. Additional universally conserved components of the translation system include about 30 tRNAs, several translation factors, 18 aminoacyl-tRNA synthetases, and several tRNA modification enzymes ( Koonin, the logic of chance, page 213) Eukaryotic and prokaryotic ribosomal subunits differ
significantly in size and complexity. 3
In bacteria, the large 50S ribosomal subunit has 31 proteins, and the small 30S ribosomal subunit has 21 proteins. In eukaryotes, the large 60S ribosomal subunit has 49 proteins, and the small 40S ribosomal subunit has 33 proteins.
Ribosome biogenesis
Ribosome biogenesis is one of the most crucial and energy-consuming processes of any cell. In eukaryotic cells ribosomes are preassembled in the nucleus and exported to the cytoplasm where they undergo final maturation. This involves the release of trans-acting shuttling factors, transport factors, incorporation of the remaining ribosomal proteins, and final rRNA processing steps. 4 In eukaryotic cells, ribosome biogenesis requires the coordinated activity of all three RNA polymerases and the orchestrated work of many (>200) transiently associated ribosome assembly factors. A large number of non-ribosomal factors (N 200) and snoRNAs (75), and ∼100 molecular chaperones are involved in ribosome assembly 3
1. https://en.wikipedia.org/wiki/Messenger_RNA
2. https://jcs.biologists.org/content/126/21/4815
3. https://sci-hub.tw/https://www.sciencedirect.com/science/article/pii/S0167488909002651?via%3Dihub
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2866757/#:~:text=In%20eukaryotic%20cells%20ribosomes%20are,and%20final%20rRNA%20processing%20steps.
One of the principal molecular nano factories required to give life a first go is the Ribosome which translates the digital information in messenger RNA into the amino acid alphabet, the analog information which polymerizes amino acids to produce proteins, information enriched polymers. But there is an entire armada of proteins and ribozymes required for this central process. I will list what is required, here.
Comparative genomic reconstructions of the gene repertoire of LUCA(S) point to a complex translation system that includes at least 18 of the 20 aminoacyl-tRNA synthetases (aaRS), several translation factors, at least 40 ribosomal proteins, and several enzymes involved in rRNA and tRNA modification. It appears that the core of the translation system was already fully shaped in LUCA(S) (Anantharaman, et al., 2002).
Koonin, the logic of chance, page 376
Breaking the evolution of the translation system into incremental steps, each associated with a biologically plausible selective advantage is extremely difficult even within a speculative scheme let alone experimentally.
Messenger RNA
Messenger RNA (mRNA) is a single-stranded RNA molecule that corresponds to the genetic sequence of a gene and is read by the ribosome in the process of producing a protein. Non-eukaryotic mRNA is, in essence, mature upon transcription and requires no processing, except in rare cases. Eukaryotic pre-mRNA requires several processing steps before its transport to the cytoplasm and its translation by the ribosome. That includes Splicing, 5' cap addition, Editing, Polyadenylation, Transport, mRNAs must be exported from the nucleus to the cytoplasm—a process regulated by different signaling pathways. 1 RNA repair has now been demonstrated to be a genuine biological process and appears to be present in all three domains of life. As with DNA, RNA can be damaged as well as incorrectly copied. The cell checks that an mRNA is correctly synthesized and deals with incorrectly copied RNAs through quality control. In both eukaryotes and bacteria, there are mechanisms for eliminating transcripts that fail to pass quality control. Without proofreading and repair, the number of mRNAs carrying coding errors could be significant.
The Ribosome
All cells use homologous ribosomes that consist of three universally conserved RNA molecules and some 50 proteins, of which about 20 are universally conserved. Additional universally conserved components of the translation system include about 30 tRNAs, several translation factors, 18 aminoacyl-tRNA synthetases, and several tRNA modification enzymes ( Koonin, the logic of chance, page 213) Eukaryotic and prokaryotic ribosomal subunits differ
significantly in size and complexity. 3
In bacteria, the large 50S ribosomal subunit has 31 proteins, and the small 30S ribosomal subunit has 21 proteins. In eukaryotes, the large 60S ribosomal subunit has 49 proteins, and the small 40S ribosomal subunit has 33 proteins.
Ribosome biogenesis
Ribosome biogenesis is one of the most crucial and energy-consuming processes of any cell. In eukaryotic cells ribosomes are preassembled in the nucleus and exported to the cytoplasm where they undergo final maturation. This involves the release of trans-acting shuttling factors, transport factors, incorporation of the remaining ribosomal proteins, and final rRNA processing steps. 4 In eukaryotic cells, ribosome biogenesis requires the coordinated activity of all three RNA polymerases and the orchestrated work of many (>200) transiently associated ribosome assembly factors. A large number of non-ribosomal factors (N 200) and snoRNAs (75), and ∼100 molecular chaperones are involved in ribosome assembly 3
1. https://en.wikipedia.org/wiki/Messenger_RNA
2. https://jcs.biologists.org/content/126/21/4815
3. https://sci-hub.tw/https://www.sciencedirect.com/science/article/pii/S0167488909002651?via%3Dihub
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2866757/#:~:text=In%20eukaryotic%20cells%20ribosomes%20are,and%20final%20rRNA%20processing%20steps.
