3u97

1.1 Angstrom-resolution crystal structure of the Brucella abortus ribonuclease toxin, BrnT

spinqualitylabelsall models 3u97, resolution 1.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3u97 is a 1 chain structure with sequence from Brucella abortus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. NonStd Res: MSE Gene: BruAb1_0981 (Brucella abortus) Activity: Ribonuclease T(2), with EC number 3.1.27.1 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Type two toxin-antitoxin (TA) systems are expressed from two-gene operons that encode a cytoplasmic protein toxin and its cognate protein antitoxin. These gene cassettes are often present in multiple copies on bacterial chromosomes, where they have been reported to regulate stress adaptation and persistence during antimicrobial treatment. We have identified a novel type II TA cassette in the intracellular pathogen Brucella abortus that consists of the toxin gene, brnT, and its antitoxin, brnA. BrnT is coexpressed and forms a 2:2 tetrameric complex with BrnA, which neutralizes BrnT toxicity. The BrnT2-BrnA2 tetramer binds its own promoter via BrnA, and autorepresses its expression; its transcription is strongly induced in B. abortus by various stressors encountered by the bacterial cell during infection of a mammalian host. Although highly divergent at the primary sequence level, an atomic resolution (1.1 A) crystal structure of BrnT reveals a secondary topology related to the RelE family of type II ribonuclease toxins. However, overall tertiary structural homology to other RelE family toxins is low. A functional characterization of BrnT by site-directed mutagenesis demonstrates a correspondence between its in vitro activity as a ribonuclease and control of bacteriostasis in vivo. We further present an analysis of the conserved and variable features of structure required for RNA scission in BrnT and the RelE toxin family. This structural investigation informs a model of the RelE fold as an evolutionarily-flexible scaffold that has been selected to bind structurally disparate antitoxins, and exhibit distinct toxin activities including RNA scission and DNA gyrase inhibition. Molecular structure and function of the novel BrnT/BrnA toxin-antitoxin system of Brucella abortus.,Heaton BE, Herrou J, Blackwell AE, Wysocki VH, Crosson S J Biol Chem. 2012 Feb 14. PMID:22334680 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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