Download MendeleyStructure-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, M.C., Letoquart, J., Li de la Sierra-Gallay, I., Forterre, P., Collinet, B., van Tilbeurgh, H., Basta, T.(2018) RNA 24: 926-938
- PubMed: 29650678
- DOI: https://doi.org/10.1261/rna.066092.118
- Primary Citation of Related Structures:
6F87, 6F89, 6F8Y - PubMed Abstract:
N 6 -threonyl-carbamoyl adenosine (t 6 A) 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). t 6 A stabilizes the codon-anticodon interaction and hence promotes translation fidelity. The first step of the biosynthesis of t 6 A, 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 a different mechanism for TC-AMP synthesis.
Organizational Affiliation:
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France.
