6f87 | pdb_00006f87

Crystal structure of P. abyssi Sua5 complexed with L-threonine and PPi

spinqualitylabelsall models 6f87, resolution 2.62Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6f87 is a 4 chain structure with sequence from Pyrab. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: POP, THR Gene: sua5, PYRAB15960, PAB1302 (PYRAB) Activity: L-threonylcarbamoyladenylate synthase, with EC number 2.7.7.87 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [SUA5_PYRAB] Required for the formation of a threonylcarbamoyl group on adenosine at position 37 (t(6)A37) in tRNAs that read codons beginning with adenine. Likely catalyzes the conversion of L-threonine, HCO(3)(-)/CO(2) and ATP to give threonylcarbamoyl-AMP (TC-AMP) as the acyladenylate intermediate, with the release of diphosphate. Does not bind tRNA. Publication Abstract from PubMed N6-threonyl-carbamoyl adenosine (t6A) is a universal tRNA modification found at position 37, next to the anticodon, in almost all tRNAs decoding ANN codons (where N = A, U, G or C). t6A stabilizes the codon-anticodon interaction and hence promotes translation fidelity. The first step of the biosynthesis of t6A, the production of threonyl-carbamoyl adenylate (TC-AMP), is catalyzed by the Sua5/TsaC family of enzymes. While TsaC is a single domain protein, Sua5 enzymes are composed of the TsaC-like domain, a linker and an extra domain called SUA5 of unknown function. In the present study, we report structure-function analysis of Pyrococcus abyssi Sua5 (Pa-Sua5). Crystallographic data revealed binding sites for bicarbonate substrate and pyrophosphate product. The linker of Pa-Sua5 forms a loop structure that folds into the active site gorge and closes it. Using structure-guided mutational analysis we established that the conserved sequence motifs in the linker and the domain-domain interface are essential for the function of Pa-Sua5. We propose that the linker participates actively in the biosynthesis of TC-AMP by binding to ATP/PPi and by stabilizing the N-carboxy-L-threonine intermediate. Hence, TsaC orthologs which lack such a linker and SUA5 domain use different mechanism for TC-AMP synthesis. Structure-function analysis of Sua5 protein reveals novel functional motifs required for the biosynthesis of the universal t6A tRNA modification.,Pichard-Kostuch A, Zhang W, Liger D, Daugeron MC, Letoquart J, Li de la Sierra-Gallay I, Forterre P, Collinet B, van Tilbeurgh H, Basta T RNA. 2018 Apr 12. pii: rna.066092.118. doi: 10.1261/rna.066092.118. PMID:29650678 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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