Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand.
J Microbiol. 2013 Dec;51(6):783-90. doi: 10.1007/s12275-013-2619-6. Epub 2013 Dec 19.
The aspS gene encoding Aspartyl-tRNA synthetase (AspRS) from a thermotolerant acetic acid bacterium, Acetobacter pasteurianus SKU1108, has been cloned and characterized. The open reading frame (ORF) of the aspS gene consists of 1,788 bp, encoding 595 amino acid residues. The highly conserved Gly-Val-Asp-Arg ATP binding motif (motif 3) is located at the position 537-540 in the C-terminus. Deletion analysis of the aspS gene upstream region suggested that the promoter is around 173 bp upstream from the ATG initiation codon. Interestingly, transformation with the plasmids pGEM-T138, pUC138, and pCM138 synthesizing 138 amino acid C-terminal fragments of AspRS, that carry the ATP binding domain, caused E. coli cell lengthening at 37 and 42°C. Moreover, E. coli harboring pUC595 (synthesizing all 595 amino acids) and a disordered aspS gene in pGEM-T138 had normal rod shapes. The normal rod shape was observed in E. coli harboring pD539V following site-directed mutagenesis of the ATP binding domain. We propose that over-production of truncated C-terminal peptides of AspRS may cause sequestration of intracellular ATP in E. coli, leaving less ATP for cell division or shaping cell morphology.
已克隆并鉴定了耐温性醋酸菌醋化醋杆菌 SKU1108 的天冬氨酰-tRNA 合成酶（AspRS）编码基因 aspS。aspS 基因的开放阅读框（ORF）由 1788bp 组成，编码 595 个氨基酸残基。高度保守的 Gly-Val-Asp-Arg ATP 结合基序（基序 3）位于 C 末端的 537-540 位。aspS 基因上游区缺失分析表明，启动子位于 ATG 起始密码子上游约 173bp 处。有趣的是，转化带有质粒 pGEM-T138、pUC138 和 pCM138 的 E. coli，这三种质粒合成 AspRS 的 138 个氨基酸 C 末端片段，携带 ATP 结合结构域，会导致 E. coli 在 37°C 和 42°C 下细胞变长。此外，携带 pUC595（合成所有 595 个氨基酸）和 pGEM-T138 中无序 aspS 基因的 E. coli 具有正常的杆状形状。在定向突变 ATP 结合结构域后，E. coli 携带 pD539V 时观察到正常的杆状形状。我们提出，AspRS 截断 C 末端肽的过度表达可能导致细胞内 ATP 在 E. coli 中被隔离，从而减少 ATP 用于细胞分裂或塑造细胞形态。
