The researchers were inspired by ribosomes , This figure shows ribosomal translation RNA chain . picture source ：Omikron/Science Photo Library
The study supports the idea that “RNA The world ” Another statement based on the hypothesis ,“RNA The world ” The hypothesis is that , stay DNA And the protein it encodes before it evolved , The first organism is based on RNA The chain . Standard theory holds that , stay “RNA The world ” in , Life can be complex and primitive RNA Chain form existence , They can copy themselves , And can compete with other chains . later , these “RNA enzyme ” May have evolved the ability to make proteins , And finally transform their genetic information into more stable DNA.
But how this happens is still a question , Part of the reason is that RNA The efficiency of the composed catalyst is far lower than that of the protein enzymes found in all living cells today . The study's corresponding author 、 Organic chemist, University of Munich, Germany Thomas Carell Think , Despite the discovery of RNA catalyst , But their catalytic ability is very poor .
When studying this problem , The researchers were RNA Inspiration for its role in the manufacture of proteins in all modern organisms ： Genes that encode RNA chain （ Is usually DNA The base sequence is copied from ） Through ribosomes , Ribosomes produce one amino acid at a time , Form the corresponding protein .
Unlike most enzymes , Ribosomes themselves are not just made up of proteins , It's up to you RNA Fragment composition , These fragments play an important role in the synthesis of proteins . Besides , Ribosomes contain standard RNA Nucleoside A、C、G、U A modified version of .
The researchers connected two segments common in living cells RNA, A synthetic RNA molecular , These include two modified nucleosides . At the first specific nucleoside site , Synthetic molecules can bind to an amino acid , Then the amino acid laterally binds to the adjacent second specific nucleoside . And then , The researchers separated the original RNA chain , And introduces a new RNA chain , The RNA Chains carry their own amino acids , And form strong covalent bonds with amino acids previously attached to the second chain .
This process is carried out step by step , A short chain of amino acids , Mini protein —— peptide , And attached to RNA On . The formation of chemical bonds between amino acids requires energy , Researchers provide energy by stimulating amino acids with various reactants in solution .
Martin Express , This is a very exciting discovery .“ Not only because it is based on RNA The formation of peptides indicates a new path , The discovery also reveals naturally occurring RNA New evolutionary significance of modified bases .”Martin Add , The result shows that RNA Played an important role in the origin of life .
Biophysical chemist at Georgia Institute of technology Loren Williams Agree with this , He thinks that , If RNA The origin of protein is related to the origin of protein , And their emergence is not independent , Then this will fundamentally turn to support “RNA - Protein world ”, And away “RNA The world ”.
To prove that this is a reasonable origin of life , Scientists must take a few further steps . The team RNA The peptides formed on are composed of random sequences of amino acids , Instead of being stored in RNA Determined by the information in .Carell say , Bigger RNA The structure can be folded in a specific position “ distinguish ” The shape of a particular amino acid , Produce a definite structure . These are complicated RNA- Peptide mixtures may have catalytic properties , And influenced by evolutionary pressure , Become more efficient .Carell Think , If molecules can replicate , There will be similar micro organisms .
author ： Xinyu source ： Science China Press