6y2p

Escherichia coli RnlA-RnlB Toxin-Antitoxin System.

spinqualitylabelsall models 6y2p, resolution 2.64Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6y2p is a 4 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.64Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RNLA_ECOLI Toxic component of a toxin-antitoxin (TA) module. A stable (half-life 27.6 minutes) endoribonuclease that in the absence of cognate antitoxin RnlB causes generalized RNA degradation. Degrades late enterobacteria phage T4 mRNAs, protecting the host against T4 reproduction. Activity is inhibited by cognate antitoxin RnlB and by enterobacteria phage T4 protein Dmd. Targets cyaA mRNA. Publication Abstract from PubMed The rnlAB toxin-antitoxin operon from Escherichia coli functions as an anti-phage defense system. RnlA was identified as a member of the HEPN (Higher Eukaryotes and Prokaryotes Nucleotide-binding domain) superfamily of ribonucleases. The activity of the toxin RnlA requires tight regulation by the antitoxin RnlB, the mechanism of which remains unknown. Here we show that RnlA exists in an equilibrium between two different homodimer states: an inactive resting state and an active canonical HEPN dimer. Mutants interfering with the transition between states show that canonical HEPN dimerization via the highly conserved RX4-6H motif is required for activity. The antitoxin RnlB binds the canonical HEPN dimer conformation, inhibiting RnlA by blocking access to its active site. Single-alanine substitutions mutants of the highly conserved R255, E258, R318 and H323 show that these residues are involved in catalysis and substrate binding and locate the catalytic site near the dimer interface of the canonical HEPN dimer rather than in a groove located between the HEPN domain and the preceding TBP-like domain. Overall, these findings elucidate the structural basis of the activity and inhibition of RnlA and highlight the crucial role of conformational heterogeneity in protein function. Alternative dimerization is required for activity and inhibition of the HEPN ribonuclease RnlA.,Garcia-Rodriguez G, Charlier D, Wilmaerts D, Michiels J, Loris R Nucleic Acids Res. 2021 Jul 9;49(12):7164-7178. doi: 10.1093/nar/gkab513. PMID:34139012 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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