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From Proteopedia
Structure of the Shigella flexneri VapC mutant D7N
Structural highlights
Function[VAPC_SHIFL] Toxic component of a toxin-antitoxin (TA) module. A tRNA-(fMet) endonuclease, it cleaves both charged and uncharged tRNA-(fMet) between positions 38 and 39 at the anticodon stem-loop boundary. Does not cleave tRNA(Met), tRNA(Arg2), tRNA(His), tRNA(Leu), tRNA(Phe) tRNA(Thr1), tRNA(Tyr) or tRNA(Val). Overexpression in E.coli inhibits translation, leads to loss of cell growth and degradation of tRNA(fMet); these effects are neutralized by expression of cognate antitoxin VapB. The VapB/VapC complex probably regulates transcription of its own promoter.[1] [2] Ectopic overexpression in E.coli induces the YoeB toxin, but this is not the cause of VapC toxicity.[3] [4] Publication Abstract from PubMedThe VapC toxin from the Shigella flexneri 2a virulence plasmid pMYSH6000 belongs to the PIN domain protein family, which is characterized by a conserved fold with low amino acid sequence conservation. The toxin is a bona fide Mg2+ -dependent ribonuclease and has been shown to target initiator tRNAfMet in vivo. Here, we present crystal structures of active site catalytic triad mutants D7A, D7N, and D98N of the VapC toxin in absence of antitoxin. In all structures, as well as in solution, VapC appears as a dimer. In the D98N structure, a Hepes molecule occupies both active sites of the dimer and comparison with the structure of RNase H bound to a DNA/RNA hybrid suggests that the Hepes molecule mimics the position of a target nucleotide. This article is protected by copyright. All rights reserved. Structural analysis on the active site architecture of the VapC toxin from Shigella flexneri.,Xu K, Dedic E, Brodersen DE Proteins. 2016 Feb 2. doi: 10.1002/prot.25002. PMID:26833558[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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