Structural highlights
Function
TGT_ECOLI Catalyzes the base-exchange of a guanine (G) residue with the queuine precursor 7-aminomethyl-7-deazaguanine (PreQ1) at position 34 (anticodon wobble position) in tRNAs with GU(N) anticodons (tRNA-Asp, -Asn, -His and -Tyr). Catalysis occurs through a double-displacement mechanism. The nucleophile active site attacks the C1' of nucleotide 34 to detach the guanine base from the RNA, forming a covalent enzyme-RNA intermediate. The proton acceptor active site deprotonates the incoming PreQ1, allowing a nucleophilic attack on the C1' of the ribose to form the product. After dissociation, two additional enzymatic reactions on the tRNA convert PreQ1 to queuine (Q), resulting in the hypermodified nucleoside queuosine (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine).[HAMAP-Rule:MF_00168][1] [2]
References
- ↑ Kittendorf JD, Barcomb LM, Nonekowski ST, Garcia GA. tRNA-guanine transglycosylase from Escherichia coli: molecular mechanism and role of aspartate 89. Biochemistry. 2001 Nov 27;40(47):14123-33. doi: 10.1021/bi0110589. PMID:11714265 doi:https://dx.doi.org/10.1021/bi0110589
- ↑ Kittendorf JD, Sgraja T, Reuter K, Klebe G, Garcia GA. An essential role for aspartate 264 in catalysis by tRNA-guanine transglycosylase from Escherichia coli. J Biol Chem. 2003 Oct 24;278(43):42369-76. Epub 2003 Aug 8. PMID:12909636 doi:https://dx.doi.org/10.1074/jbc.M304323200