Ikegami A, Nakasone K, Kato C, Nakamura Y, Yoshikawa I, Usami R, Horikoshi K
The DEEPSTAR Group, Japan Marine Science and Technology Center, Yokosuka, Japan.
FEMS Microbiol Lett. 2000 Nov 1;192(1):91-5. doi: 10.1111/j.1574-6968.2000.tb09364.x.
A glutamine synthetase gene (glnA) was isolated from a deep-sea piezophilic bacterium, Shewanella violacea strain DSS12. A 7.5-kb SacI fragment containing the complete glnA gene was cloned and sequenced. The glnA gene was found to encode a protein consisting of 469 amino acid residues, showing 75.0% identity to the glutamine synthetase of Escherichia coli. Primer extension analyses revealed two transcription initiation sites in glnA and expression from each site was positively regulated by pressure. Putative promoters recognized by sigma(70) and sigma(54) were identified in the region upstream of glnA. An electrophoretic mobility shift assay demonstrated that S. violacea sigma(54) specifically binds to the promoter region of glnA, suggesting that sigma(54) may play an important role in pressure-regulated transcription in this piezophilic bacterium.
从深海嗜压细菌紫色希瓦氏菌DSS12菌株中分离出一个谷氨酰胺合成酶基因（glnA）。克隆并测序了一个包含完整glnA基因的7.5 kb SacI片段。发现glnA基因编码一种由469个氨基酸残基组成的蛋白质，与大肠杆菌的谷氨酰胺合成酶具有75.0%的同一性。引物延伸分析揭示了glnA中有两个转录起始位点，每个位点的表达都受到压力的正调控。在glnA上游区域鉴定出了被σ（70）和σ（54）识别的推定启动子。电泳迁移率变动分析表明，紫色希瓦氏菌σ（54）特异性结合glnA的启动子区域，这表明σ（54）可能在这种嗜压细菌的压力调节转录中发挥重要作用。
