Structural and mutational studies of the catalytic domain of colicin E5: A tRNA-specific ribonuclease

Yi Lun Lin, Youssef Elias, Raven H. Huang

Research output: Contribution to journalArticlepeer-review


Colicin E5 specifically cleaves four tRNAs in Escherichia coli that contain the modified nucleotide queuosine (Q) at the wobble position, thereby preventing protein synthesis and ultimately resulting in cell death. Here, the crystal structure of the catalytic domain of colicin E5 (E5-CRD) from E. coli was determined at 1.5 Å resolution. Unexpectedly, E5-CRD adopts a core folding with a four-stranded β-sheet packed against an α-helix, seen in the well-studied ribonuclease T1 despite a lack of sequence similarity. Beyond the core catalytic domain, an N-terminal helix, a C-terminal β-strand and loop, and an extended internal loop constitute an RNA binding cleft. Mutational analysis identified five amino acids that were important for tRNA substrate binding and cleavage by E5-CRD. The structure, together with the mutational study, allows us to propose a model of colicin E5-tRNA interactions, suggesting the molecular basis of tRNA substrate recognition and the mechanism of tRNA cleavage by colicin E5.

Original languageEnglish (US)
Pages (from-to)10494-10500
Number of pages7
Issue number31
StatePublished - Aug 9 2005

ASJC Scopus subject areas

  • Biochemistry


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