Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming 650500, China; Yunnan Minzu University, Kunming 650500, China.
Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming 650500, China.
J Inorg Biochem. 2022 Nov;236:111978. doi: 10.1016/j.jinorgbio.2022.111978. Epub 2022 Aug 27.
Prodigiosin (2-methyl-3-pentyl-6-methoxyprodiginine), a red-colored microbial pigment, is produced in large quantities by Serratia marcescens KMR-3. This bacterium can grow in a medium with a Cd concentration of 500 mg/L, but it does not produce prodigiosin when the Cd concentration in the medium is higher than 140 mg/L. Therefore, we investigated the mechanisms by which Cd inhibits prodigiosin synthesis. Upon addition of Cd to the medium, the expression of the prodigiosin (pig) gene cluster was significantly downregulated. Simultaneously, genes encoding proteins related to the synthesis of arginine and proline(prodigiosin precursors) were significantly downregulated, while the degradation-related genes were upregulated. Furthermore, PigF, which encodes a key enzyme involved in the synthesis of 4-methoxy-2,2'-bipyrrole-5-carboxaldehyde and PigC, which encodes a key enzyme involved in the last step of prodigiosin synthesis, were downregulated by 80% and 55%, respectively, following Cd treatment. As PigC and PigF are located on the cell membrane and are involved in the final steps of prodigiosin synthesis, the cell membrane might be presumed to be the site of prodigiosin synthesis. The bacterial membrane exhibited different degrees of elongation, folding, fragmentation, and sagging after the addition of Cd, while likely destroying the site of prodigiosin synthesis.
灵菌红素（2-甲基-3-戊基-6-甲氧基普罗迪京）是一种红色微生物色素，由粘质沙雷氏菌 KMR-3 大量产生。该细菌可以在含 500mg/L Cd 的培养基中生长，但当培养基中 Cd 浓度高于 140mg/L 时，它不会产生灵菌红素。因此，我们研究了 Cd 抑制灵菌红素合成的机制。当 Cd 被添加到培养基中时，灵菌红素（pig）基因簇的表达显著下调。同时，编码与精氨酸和脯氨酸（灵菌红素前体）合成相关的蛋白的基因显著下调，而降解相关基因则上调。此外，Cd 处理后，编码参与 4-甲氧基-2,2'-联吡啶-5-甲醛合成的关键酶的 PigF 和编码参与灵菌红素合成最后一步的关键酶的 PigC 的基因分别下调了 80%和 55%。由于 PigC 和 PigF 位于细胞膜上，并且参与灵菌红素合成的最后步骤，因此可以推测细胞膜是灵菌红素合成的部位。加入 Cd 后，细菌膜出现不同程度的伸长、折叠、碎裂和下垂，可能破坏了灵菌红素合成的部位。
