7wik | pdb_00007wik

Crystal structure of oligoribonuclease of Mycobacterium smegmatis mc2 155

spinqualitylabelsall models 7wik, resolution 1.87Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 7wik is a 4 chain structure with sequence from Mycolicibacterium smegmatis MC2 155. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, GOL, K, MG, PEG, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0R1E6_MYCS2 3'-to-5' exoribonuclease specific for small oligoribonucleotides.[HAMAP-Rule:MF_00045] Publication Abstract from PubMed Oligoribonucleases (Orns) are highly conserved DnaQ-fold 3'-5' exoribonucleases that have been found to carry out the last step of cyclic-di-GMP (c-di-GMP) degradation, that is, pGpG to GMP in several bacteria. Removal of pGpG is critical for c-di-GMP homeostasis, as excess uncleaved pGpG can have feedback inhibition on phosphodiesterases, thereby perturbing cellular signaling pathways regulated by c-di-GMP. Perturbation of c-di-GMP levels not only affects survival under hypoxic, reductive stress, or nutrient-limiting conditions but also affects pathogenicity in infection models as well as antibiotic response in mycobacteria. Here, we have determined the crystal structure of MSMEG_4724, the Orn of Mycobacterium smegmatis (Ms_orn) to 1.87 A resolution to investigate the function of its extended C-terminal tail that is unique among bacterial Orns. Ms_orn is a homodimer with the canonical RNase-H fold of exoribonucleases and conserved catalytic residues in the active site. Further examination of the substrate-binding site with a modeled pGpG emphasized the role of a phosphate cap and "3'OH cap" in constricting a 2-mer substrate in the active site. The unique C-terminal tail of Ms_orn aids dimerization by forming a handshake-like flap over the second protomer of the dimer. Our thermal and denaturant-induced unfolding experiments suggest that it helps in higher stability of Ms_orn as compared with Escherichia coli Orn or a C-terminal deletion mutant. We also show that the C-terminal tail is required for modulating response to stress agents in vivo. These results will help in further evaluating the role of signaling and regulation by c-di-GMP in mycobacteria. Three-dimensional structure of a mycobacterial oligoribonuclease reveals a unique C-terminal tail that stabilizes the homodimer.,Badhwar P, Khan SH, Taneja B J Biol Chem. 2022 Oct 14;298(12):102595. doi: 10.1016/j.jbc.2022.102595. PMID:36244449 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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