RloC: A wobble nucleotide-excising and zinc-responsive bacterial tRNase

Elena Davidov, Gabriel Kaufmann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The conserved bacterial protein RloC, a distant homologue of the tRNA Lys anticodon nuclease (ACNase) PrrC, is shown here to act as a wobble nucleotide-excising and Zn++-responsive tRNase. The more familiar PrrC is silenced by a genetically linked type I DNA restriction-modification (R-M) enzyme, activated by a phage anti-DNA restriction factor and counteracted by phage tRNA repair enzymes. RloC shares PrrC's ABC ATPase motifs and catalytic ACNase triad but features a distinct zinc-hook/coiled-coil insert that renders its ATPase domain similar to Rad50 and related DNA repair proteins. Geobacillus kaustophilus RloC expressed in Escherichia coli exhibited ACNase activity that differed from PrrC's in substrate preference and ability to excise the wobble nucleotide. The latter specificity could impede reversal by phage tRNA repair enzymes and account perhaps for RloC's more frequent occurrence. Mutagenesis and functional assays confirmed RloC's catalytic triad assignment and implicated its zinc hook in regulating the ACNase function. Unlike PrrC, RloC is rarely linked to a type I R-M system but other genomic attributes suggest their possible interaction in trans. As DNA damage alleviates type I DNA restriction, we further propose that these related perturbations prompt RloC to disable translation and thus ward off phage escaping DNA restriction during the recovery from DNA damage.

Original languageEnglish
Pages (from-to)1560-1574
Number of pages15
JournalMolecular Microbiology
Volume69
Issue number6
DOIs
StatePublished - Sep 2008

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