Instituto de Biología Funcional y Genómica/Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas CSIC/Universidad de Salamanca, Salamanca, Spain.
FEMS Microbiol Lett. 2013 May;342(2):123-9. doi: 10.1111/1574-6968.12098. Epub 2013 Feb 28.
Phosphate metabolism regulates most of the life processes of microorganisms. In the present work we obtained and studied a Streptomyces lividans ppk/pstS double mutant, which lacks polyphosphate kinase (PPK) and the high-affinity phosphate-binding protein (PstS), impairing at the same time the intracellular storage of polyphosphate and the intake of new inorganic phosphate from a phosphate-limited medium, respectively. In some of the aspects analyzed, the ppk/pstS double mutant was more similar to the wt strain than was the single pstS mutant. The double mutant was thus able to grow in phosphate-limited media, whereas the pstS mutant required the addition of 1 mM phosphate under the assay conditions used. The double mutant was able to incorporate more than one fourth of the inorganic phosphate incorporated by the wt strain, whereas phosphate incorporation was almost completely impaired in the pstS mutant. Noteworthy, under phosphate limitation conditions, the double ppk/pstS mutant showed a higher production of the endogenous antibiotic actinorhodin and the heterologous antitumor 8-demethyl-tetracenomycin (up to 10-fold with respect to the wt strain), opening new possibilities for the use of this strain in the heterologous expression of antibiotic pathways.
磷酸盐代谢调节微生物的大多数生命过程。在本工作中，我们获得并研究了一个缺失多磷酸盐激酶（PPK）和高亲和力磷酸盐结合蛋白（PstS）的链霉菌 lividans ppk/pstS 双突变体，分别同时破坏了多磷酸盐的细胞内储存和从磷酸盐限制培养基中摄取新的无机磷酸盐。在分析的某些方面，ppk/pstS 双突变体比单 pstS 突变体更类似于 wt 菌株。因此，双突变体能够在磷酸盐限制培养基中生长，而 pstS 突变体在使用的测定条件下需要添加 1mM 磷酸盐。双突变体能够掺入超过 wt 菌株掺入的无机磷酸盐的四分之一以上，而 pstS 突变体几乎完全抑制了磷酸盐的掺入。值得注意的是，在磷酸盐限制条件下，双 ppk/pstS 突变体表现出更高的内源性抗生素放线紫红素和异源抗肿瘤 8-去甲基-四烯霉素的产生（相对于 wt 菌株增加了 10 倍），为该菌株在抗生素途径的异源表达中开辟了新的可能性。
