A genomic survey shows that the haloarchaeal type tyrosyl tRNA synthetase is not a synapomorphy of opisthokonts.

The haloarchaeal-type tyrosyl tRNA synthetase (tyrRS) have previously been proposed to be a molecular synapomorphy of the opisthokonts. To re-evaluate this we have performed a taxon-wide genomic survey of tyrRS in eukaryotes and prokaryotes. Our phylogenetic trees group eukaryotes with archaea, with all opisthokonts sharing the haloarchaeal-type tyrRS. However, this type of tyrRS is not exclusive to opisthokonts, since it also encoded by two amoebozoans. Whether this is a consequence of lateral gene transfer or lineage sorting remains unsolved, but in any case haloarchaeal-type tyrRS is not a synapomorphy of opisthokonts. This demonstrates that molecular markers should be re-evaluated once a better taxon sampling becomes available.