Key laboratory of Biotechnology of Antibiotics, Ministry of Health, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China.
Biochimie. 2011 Sep;93(9):1401-7. doi: 10.1016/j.biochi.2011.04.014. Epub 2011 May 12.
Streptomyces sp. 139 produces a novel exopolysaccharide (EPS) designated Ebosin which can bind IL-1R specifically and exhibits anti-rheumatic arthritis activity in vivo. With the Ebosin biosynthesis gene cluster (ste) consisting of 27 ORFs identified previously the focus of this study was to characterize the protein encoded by ste26 gene. After cloning and expressing ste26 in Escherichia coli BL21, we purified the recombinant Ste26 protein and revealed its ability of transferring the acetyl group from AcCoA to spermidine and spermine, with spermine being the preferred substrate. Therefore Ste26 has been determined to be a spermidine/spermine acetyltransferase which can use spermine (Km of 72.1 ± 7.4 μM), spermidine (Km of 147.2 ± 11 μM), AcCoA (Km of 45.7 ± 2.5 μM) and poly-l-lysine (Km of 99.7 ± 11 μM) as substrates. The optimum pH, temperature and time for the activity have been shown to be 7.5, 37°C and 10 min, respectively. This is the first spermidine/spermine acetyltransferase characterized in Streptomyces and its function in Ebosin biosynthesis is discussed.
链霉菌 139 产生一种新型胞外多糖 (EPS)，命名为 Ebosin，它可以特异性结合 IL-1R，并在体内表现出抗风湿性关节炎活性。以前已经确定了由 27 个 ORF 组成的 Ebosin 生物合成基因簇 (ste)，本研究的重点是研究 ste26 基因编码的蛋白质。在将 ste26 基因克隆并在大肠杆菌 BL21 中表达后，我们纯化了重组 Ste26 蛋白，并揭示了它将乙酰基从 AcCoA 转移到精胺和亚精胺的能力，其中亚精胺是首选底物。因此，Ste26 被确定为一种精胺/亚精胺乙酰转移酶，可使用精胺 (Km 为 72.1 ± 7.4 μM)、精胺 (Km 为 147.2 ± 11 μM)、AcCoA (Km 为 45.7 ± 2.5 μM) 和聚-l-赖氨酸 (Km 为 99.7 ± 11 μM) 作为底物。该酶的最适 pH、温度和时间分别为 7.5、37°C 和 10 分钟。这是首次在链霉菌中鉴定出的精胺/亚精胺乙酰转移酶，并讨论了其在 Ebosin 生物合成中的功能。
