23S ribosomal RNA
Encyclopedia
The 23S rRNA is a 2904 nt
long (in E. coli
) component of the large prokaryotic subunit (50S
)
The ribosomal peptidyl transferase
activity resides in this rRNA. This is achieved by a base A2486 which the nitrogen at position 3 acts as a base and accepts the H from the amino group of the aa-tRNA in the A site, the aa-tRNA with its free electron (nucleophile
) reacts
with the carboxyl group of the peptide ester
linked to the tRNA in the P site. The Oxygen reforms its double bond and the P site tRNA leaves thanks to the donation of the proton by the adenine base.
The adenine base can accept the proton in the first place thanks to several bases with which it coordinates and potassium ion acting as a charge relay.
Chloramphenicol
binds to A2451 and A2452 residues in the 23S rRNA of the ribosome
and inhibits peptide bond formation. Linezolid
and quinupristin-dalfopristin also bind to the 23S rRNA and cross-resistance has been demonstrated between these antibiotics.
Nucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
long (in E. coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
) component of the large prokaryotic subunit (50S
50S
50S is the larger subunit of the 70S ribosome of prokaryotes. It is the site of inhibition for antibiotics such as macrolides, chloramphenicol, clindamycin, and the pleuromutilins. It includes the subunits 5S and 23S.-Structure:...
)
The ribosomal peptidyl transferase
Peptidyl transferase
The Peptidyl transferase is an aminoacyltransferase as well as the primary enzymatic function of the ribosome, which forms peptide links between adjacent amino acids using tRNAs during the translation process of protein biosynthesis....
activity resides in this rRNA. This is achieved by a base A2486 which the nitrogen at position 3 acts as a base and accepts the H from the amino group of the aa-tRNA in the A site, the aa-tRNA with its free electron (nucleophile
Nucleophile
A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...
) reacts
Nucleophilic acyl substitution
Nucleophilic acyl substitution describes the substitution reaction involving nucleophiles and acyl compounds. Acyl compounds are carboxylic acid derivatives including esters, amides and acid halides...
with the carboxyl group of the peptide ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
linked to the tRNA in the P site. The Oxygen reforms its double bond and the P site tRNA leaves thanks to the donation of the proton by the adenine base.
The adenine base can accept the proton in the first place thanks to several bases with which it coordinates and potassium ion acting as a charge relay.
Chloramphenicol
Chloramphenicol
Chloramphenicol is a bacteriostatic antimicrobial that became available in 1949. It is considered a prototypical broad-spectrum antibiotic, alongside the tetracyclines, and as it is both cheap and easy to manufacture it is frequently found as a drug of choice in the third world.Chloramphenicol is...
binds to A2451 and A2452 residues in the 23S rRNA of the ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....
and inhibits peptide bond formation. Linezolid
Linezolid
Linezolid is a synthetic antibiotic used for the treatment of serious infections caused by Gram-positive bacteria that are resistant to several other antibiotics...
and quinupristin-dalfopristin also bind to the 23S rRNA and cross-resistance has been demonstrated between these antibiotics.