3tnd
From Proteopedia
Crystal structure of Shigella flexneri VapBC toxin-antitoxin complex
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] [VAPB_SHIFL] Antitoxin component of a toxin-antitoxin (TA) module. Upon expression in E.coli neutralizes the effect of cognate toxin VapC. The VapB/VapC complex probably regulates transcription of its own promoter.[5] [6] Publication Abstract from PubMedToxin-antitoxin (TA) loci are common in archaea and prokaryotes and allow cells to rapidly adapt to changing environmental conditions through release of active regulators of metabolism. Many toxins are endonucleases that target cellular mRNA and tRNAs, while the antitoxins tightly wrap around the toxins to inhibit them under normal circumstances. The antitoxins also bind to operators in the promoter regions of the cognate TA operon and thereby regulate transcription. For enteric vapBC TA loci, the VapC toxins specifically cleave tRNA(fMet) and thus down-regulate protein synthesis. Here, we describe the crystal structure of the intact Shigella flexneri VapBC TA complex, determined to 2.7 A resolution. Both in solution and in the crystal structure, four molecules of each protein combine to form a large and globular hetero-octameric assembly with SpoVT/AbrB-type DNA-binding domains at each end and a total molecular mass of about 100 kDa. The structure gives new insights into the inhibition of VapC toxins by VapB and provides the molecular basis for understanding transcriptional regulation through VapB dimerization. Crystal Structure of the VapBC Toxin-Antitoxin Complex from Shigella flexneri Reveals a Hetero-Octameric DNA-Binding Assembly.,Dienemann C, Boggild A, Winther KS, Gerdes K, Brodersen DE J Mol Biol. 2011 Oct 20. PMID:22037005[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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