6vte

Naegleria gruberi RNA Ligase K170M mutant with AMP and Mn

spinqualitylabelsall models 6vte, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6vte is a 1 chain structure with sequence from Naegleria gruberi. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: AMP, MN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function D2W2Z5_NAEGR Publication Abstract from PubMed Naegleria gruberi RNA ligase (NgrRnl) exemplifies the Rnl5 family of adenosine triphosphate (ATP)-dependent polynucleotide ligases that seal 3'-OH RNA strands in the context of 3'-OH/5'-PO4 nicked duplexes. Like all classic ligases, NgrRnl forms a covalent lysyl-AMP intermediate. A two-metal mechanism of lysine adenylylation was established via a crystal structure of the NgrRnl*ATP*(Mn2+)2 Michaelis complex. Here we conducted an alanine scan of active site constituents that engage the ATP phosphates and the metal cofactors. We then determined crystal structures of ligase-defective NgrRnl-Ala mutants in complexes with ATP/Mn2+. The unexpected findings were that mutations K170A, E227A, K326A and R149A (none of which impacted overall enzyme structure) triggered adverse secondary changes in the active site entailing dislocations of the ATP phosphates, altered contacts to ATP, and variations in the numbers and positions of the metal ions that perverted the active sites into off-pathway states incompatible with lysine adenylylation. Each alanine mutation elicited a distinctive off-pathway distortion of the ligase active site. Our results illuminate a surprising plasticity of the ligase active site in its interactions with ATP and metals. More broadly, they underscore a valuable caveat when interpreting mutational data in the course of enzyme structure-function studies. Caveat mutator: alanine substitutions for conserved amino acids in RNA ligase elicit unexpected rearrangements of the active site for lysine adenylylation.,Unciuleac MC, Goldgur Y, Shuman S Nucleic Acids Res. 2020 Apr 21. pii: 5823197. doi: 10.1093/nar/gkaa238. PMID:32315072 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also RNA ligase

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