This division is defined by the unique architectures associated with the catalytic domains and by signature sequences specific to each class.
The C-terminal moiety of the YARSs varies in sequence, length and organization and is involved in the recognition of the tRNA anticodon.
The crystal structure of the complex between YARS from Methanococcus jannaschii, tRNA(Tyr) and L-tyrosine has been solved at 1.95 Å resolution.
[13] The crystal structures of the YARSs from Archeoglobus fulgidus, Pyrococcus horikoshii and Aeropyrum pernix have also been solved at high resolution.[14](M.
[15] The structure of the complex between YARS from Saccharomyces cerevisiae, tRNA(Tyr) and an analog of tysosyl-adenylate has been solved at 2.4 Å resolution.
Their C-terminal moiety includes both α-ACB and S4-like domains like the eubacterial YARSs and share a low sequence identity with their cytosolic relatives.
The crystal structure of a complex between a recombinant H. sapiens mt-YARS, devoid of the S4-like domain, and an analog of tyrosyl-adenylate has been solved at 2.2 Å resolution.
The crystal structure of a C-terminally truncated N. crassa mt-YARS that functions in splicing group I introns, has been determined at 1.95 Å resolution.
The structure of the complex between a group I intron ribozyme and the splicing-active, carboxy-terminally truncated mt-YARS has been solved at 4.5 Å resolution.
The polypeptide loop that includes the KMSKS motif, is highly ordered and close to the bound substrate at the active site.
Pf-YARS is expressed in all asexual parasite stages (rings, trophozoites and schizonts) and is exported to the host erythrocyte cytosol, from where it is released into blood plasma on iRBC rupture.
Using its ELR peptide motif, Pf-YARS specifically binds to and internalizes into host macrophages, leading to enhanced secretion of the pro-inflammatory cytokines TnF-α and IL-6.
It presents a unique dimeric conformation and significant differences in its anticodon binding site, when compared with the YARSs from other organisms.
[22] The single YARS gene that is present in the genomes of trypanosomatids, codes for a protein that has twice the length of tyrosyl-tRBA synthetase from other organisms.
[23] The N-terminal domain of tyrosyl-tRNA synthetase provides the chemical groups necessary for converting the substrates tyrosine and ATP into a reactive intermediate, tyrosyl-adenylate (the first step of the aminoacylation reaction) and for transferring the amino-acid moiety from tyrosyl-adenylate to the 3'OH-CCA terminus of the cognate tRNA(Tyr) (the second step of the aminoacylation reaction).
[7][8][9][29] This is in strong contrast to the other class I enzymes, which are monomeric and approach their cognate tRNA from minor groove side of the acceptor stem.