LysRS_N: N-terminal, anticodon recognition domain of lysyl-tRNA synthetases (LysRS). These enzymes are homodimeric class 2b aminoacyl-tRNA synthetases (aaRSs). This domain is a beta-barrel domain (OB fold) involved in binding the tRNA anticodon stem-loop. aaRSs catalyze the specific attachment of amino acids (AAs) to their cognate tRNAs during protein biosynthesis. This 2-step reaction involves i) the activation of the AA by ATP in the presence of magnesium ions, followed by ii) the transfer of the activated AA to the terminal ribose of tRNA. In the case of the class2b aaRSs, the activated AA is attached to the 3'OH of the terminal ribose. Included in this group are E. coli LysS and LysU. These two isoforms of LysRS are encoded by distinct genes which are differently regulated. Eukaryotes contain 2 sets of aaRSs, both of which encoded by the nuclear genome. One set concerns with cytoplasmic protein synthesis, whereas the other exclusively with mitochondrial protein synthesis. Saccharomyces cerevisiae cytoplasmic and mitochondrial LysRSs have been shown to participate in the mitochondrial import of the only nuclear-encoded tRNA of S. cerevisiae (tRNAlysCUU). The gene for human LysRS encodes both the cytoplasmic and the mitochondrial isoforms of LysRS. In addition to their housekeeping role, human lysRS may function as a signaling molecule that activates immune cells and tomato LysRS may participate in a root-specific process possibly connected to conditions of oxidative-stress conditions or heavy metal uptake. It is known that human tRNAlys and LysRS are specifically packaged into HIV-1 suggesting a role for LysRS in tRNA packaging.
Jiyao W et al.(2023). "The conserved domain database in 2023.",