Sequence Divergence of Seryl-tRNA Synthetases in Archaea

摘要: The genomic sequences of Methanococcus jannaschii and Methanobacterium thermoautotrophicum contain a structurally uncommon seryl-tRNA synthetase (SerRS) sequence lack an open reading frame (ORF) for the canonical cysteinyl-tRNA (CysRS). Therefore, it is not clear if Cys-tRNACys formed by direct aminoacylation or transformation serine misacylated to tRNACys. To address this question, we prepared SerRS from two methanogenic archaea measured enzymatic properties these proteins. was purified M. thermoautotrophicum; its N-terminal peptide matched deduced relevant ORF in data jannaschii. In addition, expressed cloned maripaludis serS gene. enzymes charged their homologous tRNAs also accepted Escherichia coli tRNA as substrate aminoacylation. Gel shift experiments showed that did mischarge tRNACys with serine. This indicates acylation organisms.