Ochs M M, Lu C D, Hancock R E, Abdelal A T
Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
J Bacteriol. 1999 Sep;181(17):5426-32. doi: 10.1128/JB.181.17.5426-5432.1999.
Pseudomonas aeruginosa can utilize arginine and other amino acids as both carbon and nitrogen sources. Earlier studies have shown that the specific porin OprD facilitates the diffusion of basic amino acids as well as the structurally analogous beta-lactam antibiotic imipenem. The studies reported here showed that the expression of OprD was strongly induced when arginine, histidine, glutamate, or alanine served as the sole source of carbon. The addition of succinate exerted a negative effect on induction of oprD, likely due to catabolite repression. The arginine-mediated induction was dependent on the regulatory protein ArgR, and binding of purified ArgR to its operator upstream of the oprD gene was demonstrated by gel mobility shift and DNase assays. The expression of OprD induced by glutamate as the carbon source, however, was independent of ArgR, indicating the presence of more than a single activation mechanism. In addition, it was observed that the levels of OprD responded strongly to glutamate and alanine as the sole sources of nitrogen. Thus, that the expression of oprD is linked to both carbon and nitrogen metabolism of Pseudomonas aeruginosa.
铜绿假单胞菌能够利用精氨酸和其他氨基酸作为碳源和氮源。早期研究表明，特异性孔蛋白OprD有助于碱性氨基酸以及结构类似的β-内酰胺抗生素亚胺培南的扩散。此处报道的研究表明，当精氨酸、组氨酸、谷氨酸或丙氨酸作为唯一碳源时，OprD的表达被强烈诱导。琥珀酸盐的添加对oprD的诱导产生负面影响，这可能是由于分解代谢物阻遏。精氨酸介导的诱导依赖于调节蛋白ArgR，凝胶迁移率变动分析和DNA酶分析证明纯化的ArgR与其在oprD基因上游的操纵子结合。然而，以谷氨酸作为碳源诱导的OprD表达不依赖于ArgR，这表明存在不止一种激活机制。此外，观察到OprD的水平对作为唯一氮源的谷氨酸和丙氨酸有强烈反应。因此，oprD的表达与铜绿假单胞菌的碳代谢和氮代谢均相关。
