Cell-Type Guanylyl transferase
.
Enzymatic reaction:
RNA triphosphatase: EC:2.7.7.50 Rhea 67012
| virus | GTase |
|---|---|
| Vaccinia (Poxvirus) | D1R (GTase-Lys-GMP) |
| Orthoflavivirus (Dengue virus) | NS5 (GTase-Arg-GMP) |
| Orbivirus(Bluetongue virus) | VP4 (GTase-Lys-GMP) |
| Mammalian orthoreovirus | Lambda2(GTase-Lys-GMP) |
| Mimivirus | MimiCE (GTase-Lys-GMP) |
| Paramecium bursaria Chlorella virus 1 | A103R (GTase-Lys-GMP) |
| Baculovirus | LEF-4 (GTase-Lys-GMP) |
| Iridovirus | ORF064L(GTase-Lys-GMP) |
Mechanism: The cellular GTases are characterized by a KxDGI/L motif that is not strictly conserved in viral enzymes. The catalytic lysine (K) acts as a nucleophile to attack the beta-gamma-phosphate bond, forming an enzyme N6 Lys-GMP intermediate and releasing a pyrophosphate. The enzyme then transfers the GMP to a 5'-diphosphate mRNA.
Conventional and unconventional mechanisms for capping viral mRNA
Etienne Decroly, Francois Ferron, Julien Lescar, Bruno Canard.
Nat Rev Microbiol. 2011 Dec 5;10(1):51-65