RRNA----ribosomal RNA

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ribosomal RNA(Ribosomal RNA, RRNA) is one of the main RNA in biological cells and is a catalytic enzyme, but it does not function when it exists alone. The function can only be performed when a ribosome (a membrane-free cell) is formed in conjunction with a variety of ribosome proteins. The formation of peptide bonds between 23S and 28S rRNA in the process of translation as a peptide-derived peptide catalyzed by peptides (including proteins). rRNA is a single-stranded RNA, but folds to form a wide range of double-stranded areas.

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• 1 rRNA in prokaryotic organisms and eukaryotic organisms
  • 1.1 70s rRNA in ribosomes
    • 1.1.1 30s rRNA precursor
    • 1.1.2  16s rRNA
    • 1.1.3 5s RRNA
    • 1.1.4 23s RRNA
  • 1.2 80S ribosomes in the rRNA
    • 1.2.1 45S rRNA precursor
    • 1.2.2 18S RRNA
    • 1.2.3 5S RRNA
    • 1.2.4 5.8S RRNA
    • 1.2.5 28S RRNA
  • 1.3 Other rRNA
• 2 importance of rRNA
• 3 Research Value
• 4 related Genes
• 5 See also
• 6 References
• 7 External Links

rRNA in prokaryotic organisms and eukaryotic organisms

The ribosomes of prokaryotic and eukaryotic organisms can be divided into two subunits that can be separated from one another:

Biological species	Type	Jaki	Small subunit
Proto-nuclear organisms	70S	50S (5S, 23S)	30S (16S)
Eukaryotic organisms	902	60S (5S, 5.8S and 28S)	40S (18S)

Note: "S" (settling rate) This unit cannot be added directly, because it represents the measurement of sedimentation velocity rather than quality. The sedimentation rate of each subunit is affected by its shape and by its quality.

rRNA in the 70S ribosome

The 70S ribosomes of prokaryotic and eukaryotic cells contain 3 different rRNA, of which 30S ribosomes contain 16S rrna,50s ribosome subunits containing 5S RRNA and 23S RRNA. ^{[1] These 3 types of rRNA are structurally distinct. [2]}

The genes for encoding bacteria three species of rRNA are often combined in a 16s-23s-5s sequence to co-transcribe in the same manipulator. In the bacterial genome, there are often multiple rrnA (for example, seven E. coli: RrnA, B, C, D, E, G, and H^{[3]), which can still be obtained from other manipulators by means of a gene conversion, when some of them are knocked out. [4] archaea exist only a single group of rRNA manipulators.}

30S rRNA precursor
Main article: 30S rRNA precursor

16S and 23S rRNA in 70S ribosomes are processed by 30S rRNA precursors, and the relative molecular mass of the 30S rRNA precursor is approximately 2 MDa. In this process, the specific base of the 30S RRNA precursor was methylated, and then hydrolyzed to produce 17S and 25S RRNA Intermediate products, and then by the role of nuclease to remove a small number of nucleotide residues will eventually be 16S and 23S RRNA respectively. The 5S rRNA is separated from the 3 ' end of the 30S rRNA. ^[5]

16S RRNA
Main article: 16S RRNA

The 30S ribosome subunits of the prokaryotic organisms contain 16S RRNA. The relative molecular mass of the 16S rRNA is approximately 0.6 MDa,^{[6] The length is about 1540 NT. [7] in the 30S ribosome subunit assembly process, 16S rRNA with its ribosome protein S4, S7, S8, S15, S17 and S20 first into a primary complex. [8]}

16S rRNA about half of the nucleotides form a chain base pair, which has about 60 spirals, and the unpaired part of the molecule forms a synaptic ring. In the presence of sufficient concentrations of mg2+, the isolated 16S rRNA is in close condition, similar to the structure of the 30S ribosome subunit. It has been found that some sequences in 16S rRNA are related to the combination of 30S ribosomal subunits, mRNA and some translation factors in protein synthesis. ^{[9] The 3 ' end of the ribosome 16S rRNA can identify the 5 ' Dalgarno sequence of the mRNA to be translated, and[10] initiates the translation. Other studies have shown that 16S rRNA can also interact with tRNA that enter the ribosome P-site. [All]}

16S rRNA as a molecular study of taxonomy and phylogenetic evolution ^{[12] is highly valued,[13]16s rRNA sequence analysis is one of the most accurate techniques in the study of bacterial taxonomy. [14] with the rapid development of molecular biology and the application of this technology in medical microbiology research, the study of 16S rRNA as the basis of microbial classification gradually developed [15] and has been widely recognized. [+]}

The 16S rRNA part of the prokaryotic 70S ribosome a site is the action target of the aminoglycoside antibiotic, which hinders the translation of the proto-nucleus by combining with the A-site of the 16S rRNA. ^{[17] But the plasmid-mediated 16S rRNA methylation enzyme can be 16S rRNA methylation, resulting in bacteria to produce a higher resistance to the antibiotic. [+]}

5S RRNA
Main article: 5S RRNA

Basically, all 70S ribosomes and 80S ribosomes (except for a few fungi, a few protozoa, and mitochondrial ribosomes [19] of a few more advanced animals ^{) contain 5S RRNA in large bases.}

The relative molecular mass of the 5S rRNA is approximately kDa,^{[6] The length is approximately 5 NT, and[20] The molecule has a spiral. [21] It binds to ribosomes protein L5, L18, and L25 in the 50S ribosome Yaki of the 70S ribosome. [22]5s rRNA about 60% of nucleotides form a chain base pair. [9] studies have shown that the 5S rRNA has a sequence complementary to a specific sequence of tRNA. [All]}

The 5S rRNA in the 70S ribosome is considered to be a sensing device that facilitates the communication of functional centers in the ribosome and organizes translation. [ ^{25]in the absence of 5S rRNA of the ribosome's peptide-transferase activity will decline. [+]}

23S RRNA
Main article: 23S RRNA

The relative molecular mass of the 23S rRNA is approximately 1.2 MDa,^{[6] The length is about 2900 nt,[27] The molecule is more than half of the nucleotides in the molecule double chain form exists,[9] produces more than 100 spirals. [28] it in the 70S ribosome 50S sub-base with ribosomes protein L1, L2, L3, L4, L9 and L23 to form a primary complex. [29] The Electron microscope study of 23S rRNA in tight state shows that the shape of 23S rRNA is similar to the 50S ribosome subunit. [9]}

23S rRNA is the core of ribosome catalytic function,^{[30] Its structure domain Ⅴ has the activity of peptide transferase. [31] The 23S rRNA part of the ribosome p site has a specific area capable of forming a complementary base pair with the tRNA entering the ribosome. [+]}

The 23S rRNA part of the P-site is the role of the large-ring lactone antibiotic, which extends through the peptide chain with 23S rRNA obstruction. However, some bacteria can be mediated by the ERM Gene 23S rRNA ^{[33] methylation of 23S rRNA,[34] thereby reducing the affinity of the ribosome to antibiotics, and bacteria can be changed through the ribosome to affect the role of antibiotics. [+]}

rRNA in the 80S ribosome
Small subunit of ribosomal RNA in the 5 ' end domain, from RFAM data. This example is: RF00177

80S ribosomes contain 4 different rRNA, of which 40S ribosomes (small subunits) contain 18S RRNA, while 60S ribosome subunits (Jaki) contain 5S RRNA, 5.8S RRNA, and 28S RRNA.

28S, 5.8S, and 18S rRNA are transcribed by a single transcription unit (45S RDNA), separated by two inter-recording intervals. ^{[36]45s rDNA is organized in 5 gene clusters, with approximately 30-40 repetitions in each cluster (eukaryotic organisms usually have multiple rDNA backups in tandem repeats), and about 300-400 rDNA repeat segments exist in five clusters (13, 14, 15, On chromosome 21 and 22nd).}

45S rRNA precursor
Main article: 45S rRNA precursor

The 28S RRNA, 5.8S RRNA, and 18S RRNA in the 80S ribosomes are produced by a 45S RRNA precursor of about 14,000 NT in the nucleus. During processing, more than 100 nucleotides of the rRNA precursor are methylated, and a series of enzymatic reactions are cut into several RNA chains. ^[5]

18S RRNA
Main article: 18S RRNA

The 18S rRNA is a homologous RNA of 16S rRNA with a relative molecular mass of approximately 0.7 MDa,^{[6] at a length of about 1900 NT. [27]18s rRNA in addition to the 16S rRNA slightly longer and more than a few arm and ring structure, the spatial structure of the two are very similar,[9] in the ribosome play a fundamental role in the same.}

5S RRNA
Main article: 5S RRNA

5S RDNA in eukaryotic cells exist in tandem repeats (about 200-300 true 5S RDNA, and there are many scattered pseudo-genes), the largest human being on the long arm of chromosome 1th, band 41st-42nd. 5S rDNA is different from the other three types of 80S ribosomes in the rRNA gene, which is not located in the nucleus and is transcribed by RNA polymerase Iii.

5.8S RRNA
Main article: 5.8S RRNA

The relative molecular mass of the 5.8S rRNA is approximately kDa,^{[6] which is approximately NT in length. [27] also exists in the Archaea cells.}

The 5.8S rRNA in ribosomes is thought to play a role in aiding the ribosome translocation. ^{[Panax Notoginseng]}

The 5.8S rRNA can be used as an internal reference gene for miRNA detection. ^[+]

28S RRNA
Main article: 28S RRNA

The 28S rRNA is a homologous RNA of 23S rRNA with a relative molecular mass of approximately 1.7 MDa,^{[6] at a length of about 4700 NT. [27] Eukaryotic 28S rRNA is similar in structure to E. coli 23S rRNA. [9]}

other rRNA

• Mammalian cell mitochondria contain a 55S ribosome, its 28S ribosome subunit (small subunit) contains a length of about 950 NT 12S RRNA, its 39S ribosome subunit (Jaki) contains a length of about 1560 NT another 16S RRNA. ^[+]

• The chloroplast of some plant cells also contains 80S ribosomes, so there are 4 kinds of rRNA molecules.

The importance of rRNA

Some characteristics of rRNA are important in the study of species evolution and medicine.

• rRNA is a gene that is expressed in all cells, that is, all organisms that have a cellular structure have rRNA^{[39]. Therefore, it is possible to classify a certain organism by sequencing the genes of the encoded rRNA, and to calculate the difference between the relevant population or the estimated species. More than rRNA have been sequenced and the results of sequencing are stored in special databases such as Rdp-ii[40] and Silva[41].}

• The RRNA in the ribosome is a target site for a variety of clinically relevant antibiotics, for example: Barong can be specifically combined with a area of 30S small subunit of the prokaryotic ribosome (16S RRNA in the area), interfering with the normal process of translation ^{[42]. Other antibiotics that have been sterilized by the reaction with rRNA are: chloramphenicol, erythromycin, Clindamycin, Enterococci, ricin, aflatoxin, doxycycline, streptomycin, and sulfur-chain mitomycin.}

Research value

In recent years phylogenetic tree, RRNA sequence (especially small subunit rrna,ssu RRNA) became the most commonly used tree basis, because the SSU RRNA has the following characteristics:

• Moderate in length, usually 1200-1900 NT, can provide enough information but is not long.
• It is widely distributed in all cells with cellular structure, and the evolutionary process is relatively slow. The conservative zone can be used to build a unified evolutionary tree of all life, and the variable regions can be used to differentiate genera or species.
• The horizontal transfer of rRNA gene is very difficult to occur, because its function is very basic and important, it needs the fine regulation of translation mechanism to realize function.

related genes
Ribosome-Jaki ribosomal protein gene from cytoplasmic matrixShowMitochondrial ribosome-Jaki ribosomal protein geneShowRibosome-ribosomal protein gene of cytoplasmic matrix ribosome small subunitShowRibosomal protein gene of mitochondrial ribosome small subunitShowSee

• Rna
• RDNA
• Transcription
• Ribosome
• Ribosome genotyping
• Ribose nuclear protein
• Ribosome protein

RRNA----ribosomal RNA