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

为了阐明转酰胺体在氨酰tRNA（Gln-tRNA^Gln，Asn-tRNA^Asn）间接合成途径中的多分子反应机理，我们从S.金黄色葡萄球菌和铜绿假单胞菌，并形成2个transamidosomes在体外。我们成功地对铜绿假单胞菌的Asn-tRNA、Asn转酰胺体进行了结构分析。Asn-tRNA、Asn转酰胺体由tRNA、Asn、ND-AspRS和GatCAB组成，其比例为2：2：2，与生化实验结果一致。结构表明，tRNA^Asn的受体茎位于ND-AspRS的活性位点，代表tRNA^Asn氨酰化（错电荷）之前的tRNA结合情况。在氨酰化后，tRNAAsn的受体茎翻转到GatCAB的活性位点进行转酰胺。

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.