Phage T4-induced dTTP accretion bolsters a tRNase-based host defense

Daniel Klaiman, Gabriel Kaufmann

Research output: Contribution to journalArticlepeer-review

Abstract

The anticodon nuclease (ACNase) PrrC is silenced in Escherichia coli by an associated DNA restriction-modification protein, activated by the phage T4-encoded anti-DNA restriction factor Stp and counteracted by T4's tRNA repair enzymes polynucleotide kinase and RNA ligase 1. Hence, only tRNA repair-deficient phages succumb to PrrC's restriction. PrrC's ABC-ATPase motor domains are implicated in driving its activation by hydrolyzing GTP and in stabilizing the activated ACNase by avidly binding dTTP. The latter effect has been associated with dTTP's accumulation early in T4 infection when PrrC is activated. In agreement, delayed dTTP accumulation caused by dCMP deaminase deficiency coincided with impaired manifestation of PrrC's ACNase activity. This impairment did not suffice to suppress the PrrC-mediated restriction of tRNA repair deficient phage but was synthetically suppressive with a leaky stp mutation that only partly impairs PrrC's activation. Presumably, ability to gauge dTTP's changing level helps confine PrrC's toxicity to its viral target.

Original languageEnglish
Pages (from-to)97-101
Number of pages5
JournalVirology
Volume414
Issue number1
DOIs
StatePublished - 25 May 2011

Keywords

  • ABC ATPase
  • Anti-DNA restriction
  • DNA restriction
  • Phage t4
  • Polynucleotide kinase
  • PrrC
  • RNA ligase
  • RNA repair
  • Stp
  • TRNA

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