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The hidden structure of ribosomal RNA: Why are these specific shapes so critical for protein synthesis?
Ribosomal RNA (rRNA) is a noncoding RNA that is essential for protein synthesis as a major component of ribosomes in all cells. As a nuclear enzyme, rRNA carries out protein synthesis in the ribosome. rRNA is transcribed from ribosomal DNA (rDNA) and subsequently associates with ribosomal proteins to form small and large ribosomal subunits. rRNA is the physical and mechanical factor of the ribosome, enforcing the processing and translation of transfer RNA (tRNA) and messenger RNA (mRNA) to ultimately synthesize proteins. Although rRNA is never translated into protein, it makes up 80% of the RNA in most cells.
"Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins, but this ratio varies between prokaryotes and eukaryotes."
Structure of ribosomal RNA
Although the primary structure of rRNA sequences varies between different organisms, base pairing within these sequences generally forms a stem-loop structure. The length and position of the stem-loop structures of these rRNAs allow them to create similar three-dimensional structures across species. Through these structures, rRNA is able to form tight and specific interactions with ribosomal proteins to form ribosomal subunits.
"The specific structure of rRNA is closely related to the function of the ribosome."
RRNA Functions
rRNA plays an important role in the translation process, facilitating the conversion of the mRNA coding sequence into amino acids by binding to mRNA and tRNA. When tRNA is sandwiched between the small and large subunits, rRNA begins to catalyze protein synthesis. In the small subunit, the mRNA interacts with the anticodon of the tRNA, while in the large subunit, the amino acid acceptor of the tRNA interacts with the large subunit rRNA to form a ribosome-catalyzed ester-amine exchange reaction, converting a newly synthesized The C-terminus of the peptide is transferred from the tRNA to the amino acid. This series of processes can be carried out at the site of rRNA formation.
"A ribosome has three such binding sites, called the A, P, and E sites."
Assembly of rRNA
Integration of rRNA into the ribosome begins with its folding, modification, and association with ribosomal proteins to form the small subunit (SSU) and the large subunit (LSU). In prokaryotes, this process generally takes place in the cytoplasm, while in eukaryotes, it mainly occurs in the nucleolus. The synthesis of rRNA requires the participation of RNA polymerase, which makes the generation of ribosomes a key biosynthetic process in cells.
Evolution and conservation of rRNA sequences
The conservation of rRNA sequences and their ubiquity among different species provide us with a powerful tool for studying biological evolution. Because of the importance of rRNA function, these sequences have remained virtually unchanged over time. Phylogenic information is derived from 16S rRNA and has become the main method for distinguishing similar prokaryotic species. This demonstrates the key role of rRNA in biology.
Conclusion"The construction of evolutionary trees depends on the sequence changes of rRNA, which enables us to better understand the evolution of life."
The hidden structure of ribosomal RNA not only plays an indispensable role in protein synthesis, but also provides important insights into many aspects of basic biology. As research continues to deepen, we may be able to uncover more mysteries behind these structures. Will this change our understanding of the mechanisms of life?
