Bacteriophage T4 RNA ligase 2 (gp24.1) exemplifies a family of RNA ligases found in all phylogenetic domains

AUTOR(ES)

Ho, C. Kiong

FONTE

The National Academy of Sciences

RESUMO

RNA ligases participate in repair, splicing, and editing pathways that either reseal broken RNAs or alter their primary structure. Bacteriophage T4 RNA ligase (gp63) is the best-studied member of this class of enzymes, which includes yeast tRNA ligase and trypanosome RNA-editing ligases. Here, we identified another RNA ligase from the bacterial domain—a second RNA ligase (Rnl2) encoded by phage T4. Purified Rnl2 (gp24.1) catalyzes intramolecular and intermolecular RNA strand joining through ligase-adenylate and RNA-adenylate intermediates. Mutational analysis identifies amino acids required for the ligase-adenylation or phosphodiester synthesis steps of the ligation reaction. The catalytic residues of Rnl2 are located within nucleotidyl transferase motifs I, IV, and V that are conserved in DNA ligases and RNA capping enzymes. Rnl2 has scant amino acid similarity to T4 gp63. Rather, Rnl2 exemplifies a distinct ligase family, defined by variant motifs, that includes the trypanosome-editing ligases and a group of putative RNA ligases encoded by eukaryotic viruses (baculoviruses and an entomopoxvirus) and many species of archaea. These findings have implications for the evolution of covalent nucleotidyl transferases and virus-host dynamics based on RNA restriction and repair.

Documentos Relacionados

• Discovery and characterization of a thermostable bacteriophage RNA ligase homologous to T4 RNA ligase 1
• Partial Suppression of Bacteriophage T4 Ligase Mutations by T4 Endonuclease II Deficiency: Role of Host Ligase 1
• Ligase-Defective Bacteriophage T4 II. Physiological Studies
• RNA ligase reaction products in plasmolyzed Escherichia coli cells infected by T4 bacteriophage.
• Bacteriophage T4 anticodon nuclease, polynucleotide kinase and RNA ligase reprocess the host lysine tRNA.