Seryl-tRNA Synthetase (Archaeal-like)

The Archaeal-like Seryl-tRNA synthetase (SerRS-A) is an enzyme that plays a crucial role in protein synthesis by catalyzing the attachment of the amino acid serine to its cognate tRNA: $ \text{Ser} + \text{tRNA}^\text{Ser} + \text{ATP} \xrightarrow{\text{SerRS-A}} \text{Ser-tRNA}^\text{Ser} + \text{AMP} + \text{PP}_i $ SerRS-A is atypical, and is found in methanogenic archaea. It is distinct from the standard [SerRS](/class2/ser1/), which is found in most organisms. The archaeal Methanosarcina barkeri genome encodes for both variants. This enzyme has not been characterized as extensively as other aminoacyl-tRNA synthetases. The C-terminal catalytic domain SerRS-A is quite typical of a class II AARS. Like most members of the superfamily, ATP binding is coordinated by the arginine tweezers, located in motifs 2 and 3 (Kaiser et al. 2018). The catalytic domain is characterized by the ~35 residue SerRS-A insertion module located between motifs 1 and 2 (Douglas et al. 2023), which contains two $\alpha$-helices that interlock the two subunits across the dimeric interface (Bilokapic et al. 2006). The two SerRS paralogs differ primarily in their N-terminal tRNA binding domain. However, they also demonstrate distinct modes of serine binding via the catalytic domain, with the archaeal SerRS employing a tetra-coordinated zinc ion to coordinate serine binding at the active site (Bilokapic et al. 2006). In contrast to the standard SerRS, it appears that the archaeal SerRS lacks editing activity (Bilokapic et al. 2006).

References

Bilokapic, Silvija, et al. "Structure of the unusual seryl-tRNA synthetase reveals a distinct zinc dependent mode of substrate recognition." The EMBO journal 25.11 (2006): 2498-2509. Gomez, Miguel Angel Rubio, and Michael Ibba. "Aminoacyl-tRNA synthetases." Rna 26.8 (2020): 910-936. 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. Douglas, J, Bouckaert, R., Carter, C., & Wills, P. R. Enzymic recognition of amino acids drove the evolution of primordial genetic codes. Research Square (2023).