Class I Lysyl-tRNA Synthetase

The Class I lysyl-tRNA synthetase (LysRS-I) is a monomeric enzyme that plays a crucial role in protein synthesis by catalyzing the attachment of the amino acid arginine to its cognate tRNA: $ \text{Lys} + \text{tRNA}^\text{Lys} + \text{Lys} \xrightarrow{\text{LysRS-I}} \text{Lys-tRNA}^\text{Lys} + \text{AMP} + \text{PP}_i $ The C-terminal [anticodon binding domain](/superfamily/class1/Anticodon_binding_domain_EK) is α-helical rich and similar to [GluRS](/class1/glu1) (Terada et al. 2002). However, the catalytic domain is not immediately related to any other Class I synthetases, and as such, the enzyme belongs to its own subclass d (Douglas et al. 2023). Like most members of the superfamily, ATP binding is coordinated by the backbone brackets (Kaiser et al. 2018). The catalytic domain is characterized by the $\beta$-rich LysRS-I insertion module. Its functional role remains unclear. Editing activity has not been characterized for LysRS-I (Gomez and Ibba, 2020). The Class I LysRS is present in most archaea and some bacteria. Whereas, eukaryotes and most bacteria instead have a [Class II LysRS](/class2/lys). These two variants arose through convergent evolution (Terada et al. 2002).

References

Douglas, J, Bouckaert, R., Carter, C., & Wills, P. R. Enzymic recognition of amino acids drove the evolution of primordial genetic codes. Research Square (2023). Terada, Takaho, et al. "Functional convergence of two lysyl-tRNA synthetases with unrelated topologies." Nature Structural Biology 9.4 (2002): 257-262. Sugiura, Ikuko, et al. "The 2.0 Å crystal structure of Thermus thermophilus methionyl-tRNA synthetase reveals two RNA-binding modules." Structure 8.2 (2000): 197-208. Carter Jr, Charles W., et al. "Multidimensional Phylogenetic Metrics Identify Class I Aminoacyl-tRNA Synthetase Evolutionary Mosaicity and Inter-Modular Coupling." International Journal of Molecular Sciences 23.3 (2022): 1520. Carter Jr, Charles W. "Cognition, mechanism, and evolutionary relationships in aminoacyl-tRNA synthetases." Annual review of biochemistry 62.1 (1993): 715-748. Cusack, Stephen. "Eleven down and nine to go." Nature structural biology 2.10 (1995): 824-831. Kaiser, Florian, et al. "Backbone brackets and arginine tweezers delineate class I and class II aminoacyl tRNA synthetases." PLoS computational biology 14.4 (2018): e1006101. Ambrogelly, Alexandre, et al. "The Aminoacyl-tRNA Synthetases" CRC Press (2005): Chapter 8: Class I Lysyl-tRNA Synthetases. Gomez, Miguel Angel Rubio, and Michael Ibba. "Aminoacyl-tRNA synthetases." Rna 26.8 (2020): 910-936.