The study on the multi-molecular reaction mechanism of transamidosome for Gln-tRNA(Gln) synthesis

为了阐明酰胺基tRNA间接合成途径（Gln-tRNA^Gln, Asn-tRNA^Asn）中转酰胺体的多分子反应机制，我们分别从金黄色葡萄球菌和铜绿假单胞菌中过表达纯化了2个转酰胺体的6个组分，并在体外形成了2个转酰胺体。我们成功地分析了铜绿假单胞菌Asn- trna ^Asn转氨基体的结构。根据生化实验结果，Asn-tRNA^Asn转胺体的结构由tRNA^Asn、ND-AspRS和GatCAB组成，比例为2:2:2。结构表明，tRNA^Asn的受体干位于nd - aspr的活性位点，代表tRNA^Asn在氨基酰化（误电荷）之前的tRNA结合状态。氨基酰化后，tRNAAsn的受体茎向GatCAB的活性位点翻转进行转酰胺。

In order to elucidate the multi-molecular reaction mechanism of transamidosome in the indirect synthetic pathway of aminoacyl tRNA (Gln-tRNA^Gln, Asn-tRNA^Asn), we over-expressed, purified 6 components of 2 transamidosomes from S. aureus and P. aeruginosa, respectively, and formed 2 transamidosomes in vitro. We succeeded in the structural analysis of Asn-tRNA^Asn transamidosomes of P.aeruginosa. The structure of Asn-tRNA^Asn transamidosomes consisted of tRNA^Asn, ND-AspRS and GatCAB with a rate of 2:2:2, according with the result of the biochemistry experiment. The structure shown that acceptor stem of tRNA^Asn was located in the active site of ND-AspRS, representing a tRNA-binding situation before aminoacylation (mischarge) of the tRNA^Asn. After the aminoacylation, the acceptor stem of tRNAAsn flipped toward the active site of GatCAB for transamidation.