| Names | |
|---|---|
| IUPAC name N-[1-[(2R,3R,4S,5R)-3,4-dihydroxy-5-(hydroxymethyl)oxolan-2-yl]-2-oxopyrimidin-4-yl]acetamide | |
Other names
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| Identifiers | |
3D model (JSmol) | |
| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.021.087 |
| EC Number |
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| KEGG | |
PubChem CID | |
CompTox Dashboard (EPA) | |
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| Properties | |
| C11H15N3O6 | |
| Molar mass | 285.256 g·mol−1 |
| Appearance | white amorphous solid, sometimes yellow/brown |
| Density | 1.72 g/cm3 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
N4-Acetylcytidine (ac4C, ac4C) is a post-transcriptional modification found in tRNAs, [1] rRNAs, [1] and mRNAs. [1] [2] In this modification, the amino group at the N4 position of the RNA base cytosine is acetylated, resulting in the formation of an amide. [3] In vivo, this modification is considered highly conserved because it is seen in all three domains of life: archaea, bacteria, and eukarya. [3]
The first appearances of ac4C in the literature are from 1965 and 1966. [4] [5] These early studies refer to the acetylated nucleoside as N6-acetylcytidine and describe the acetylation as occurring on the exocyclic amino group of cytidine. [4] [5] After the IUPAC established a globalized nucleic acid notation in 1970, [6] the modern designation for the modified nucleotide became N4-acetyl cytidine. In 1965, M. Anteunis and M. Van Montagu report the in-vitro synthesis of N6-acetyl cytidine through the use of thiolacetic acid or α-acetoxyacrylonitrile and the characterization of the structure with proton magnetic resonance (PMR). [4] In 1966, Zachau and coworkers, reported the ellucidated primary structures of two serine tRNAs from yeast and mention the presence of N6-acetyl cytidine at the C12 position. [3] [5]
In vivo, the ac4C modification is installed by the enzyme N-acetyltransferase 10 (NAT10), sometimes with assistance from other cofactors such as THUMPD1. [1] [3] Across organisms, homologues of human NAT10 have been observed across archaea, bacteria, and eukarya. [1] In tRNA, rRNA, and mRNA, ac4C modifications are associated with contributions to efficiency of protein translation, as well as increased RNA stability. [1]
The RNA modification ac4C was first identified in tRNA in 1966, when Zachau and coworkers reported ac4C at position 12 of yeast serine tRNA. [5] In 1972, ac4C was reported at the wobble position of the E. coli elongator methionine tRNA. [7] This modification of the wobble base is thought to improve recognition of the AUG codon. [8] In tRNA for leucine and serine, the ac4C modification has been identified at position 12 in Saccharomyces cerevisiae . [9] Johansson and coworkers showed that ac4C contributes to tRNA stability. [9] Deletion of the TAN1 gene, which is required for ac4C formation, resulted in decreased levels of mature serine tRNA. [9]
In 1978, Thomas and coworkers found ac4C on rat 18S rRNA. [1] [10] In 1988, Johansen and coworkers observed ac4C in the 3' end helix of Dictyostelium discoideum 18S rRNA. [1] [11] In 1993, Bruenger and coworkers found ac4C on C. thermophila 5S rRNA. [1] [12] In 2014, Ito and coworkers reported that in HEK293 cells, NAT10 catalyzed the formation of ac4C at position 1842 on 18S rRNA. [1] [13] The acetylated rRNA has been associated with increased stability, particularly under thermal stress. [3]
In mRNA, the ac4C modification is also reported to be catalyzed by NAT10 and its homologues across species. [2] [14] In 2018, Arango and coworkers reported the ac4C modification in mRNA catalyzed by NAT10 in HeLa cells, identified the modification by using mass spectrometry and confirmed it with dot blot analysis. [14] In 2019, Tardu and coworkers quantitatively reported ac4C modifications in Saccharomyces cerevisiae using ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS) methods. [2]
In bacteria, TmcA-type RNA acetyltransferases catalyze the acetylation of the wobble base cytidine of initiator methionine tRNA. [3] [8] [15] An analysis of knockout strains in E. coli indicates that TmcA is nonessential and does not cause growth defects. [3] [8] [16]
In eukaryotes, the RNA acetyltransferases, human Nat10 and yeast Kre33, function alongside adapter proteins to install ac4C in leucine and serine tRNA and in helices 34 and 45 of 18S rRNA. [3] [13] [17] [18] Cellular studies identified the adapter proteins Thumpd1 for Nat10 and Tan1 for Kre33. [3] [9] It was also seen that rRNA acetylation requires an adapter short nucleolar RNA. [3] [18] Ito and coworkers found that Nat10 and Kre33 exclusively modified model RNAs containing a 5'-CCG-3' sequence. [3] [17]
Obtaining the modified nucleoside can be done in vitro, often with a one-pot synthesis. [4] [19] [20] In 1965, M. Anteunis and M. Van Montagu report the in-vitro synthesis of N6-acetyl cytidine through the use of thiolacetic acid or α-acetoxyacrylonitrile and the characterization of the structure with proton magnetic resonance (PMR). [4] In 1968, Montagu and coworkers also report success in obtaining the acetylated nucleoside using thioacetic acid. [19] However, they go on to say that with the nucleotide diphosphate or triphosphates, using thioacetic acid resulted in many side reactions. [19] In 1989, Bhat and coworkers reported success acetylating the nucleoside by dissolving it in dimethylformamide (DMF) and adding acetic anhydride as the acetylating agent. [20]
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