tRNA wybutosine-synthesizing protein 3
{{Short description|Enzyme}}
{{Infobox enzyme
| name = tRNA wybutosine-synthesizing protein 3
| image = TYW3 protein.png
| width = 250px
| caption = The enzyme as folded by AlphaFold
| EC_number = 2.1.1.282
| CAS_number =
| GO_code =
}}
tRNA wybutosine-synthesizing protein 3, known also as tRNAPhe 7-[(3-amino-3-carboxypropyl)-4-demethylwyosine37-N4]-methyltransferase, abbreviated to TYW3 is an S-adenosyl-L-methionine-dependent methyltransferase that is involved in the biosynthetic pathway of wybutosine, a hyper-modified guanosine possessing tricyclic base found at the 3'-position which is close to the anticodon of eukaryotic phenylalanine tRNA.{{cite web |author= |date= 7 April 2025|title= tRNA-yW synthesizing protein 3 homolog [ Homo sapiens (human) ]|url=https://www.ncbi.nlm.nih.gov/gene/127253 |website= NIH|location= |publisher=Protein Databases |access-date=26 April 2025}} TYW3 is believed to also methylate the carboxyl group of leucine to form α-leucine esters.{{cite web |last= |first= |date= 2025|title= P53177 · TYW3_YEAST|url= https://www.uniprot.org/uniprotkb/P53177/entry|website=UniProt |location= Database|publisher= |access-date=26 April 2025}} The enzyme catalyzes the following reaction,
:4-demethyl-7-[(3S)-3-amino-3-carboxypropyl]wyosine(37) + S-adenosyl-L-methionine = 7-[(3S)-3-amino-3-carboxypropyl]wyosine(37) + S-adenosyl-L-homocysteine + H+
The modifications this enzyme makes are important for translational reading-frame maintenance. TYW3 is found in all eukaryotes and in some archaea, but not in bacteria.{{cite web |author= |date= 2025|title= ENZYME entry: EC 2.1.1.282|url=https://enzyme.expasy.org/EC/2.1.1.282 |website=Expasy |location= |publisher= |access-date=26 April 2025}}{{cite web |author= |date= 2025|title=TRNA ENZYME EC NUM |url= https://www.genome.jp/dbget-bin/www_bget?ec:2.1.1.282|website= KEGG|location=Database |publisher= |access-date=26 April 2025}}