Muriel-Millán Luis Felipe, Moreno Soledad, Romero Yanet, Bedoya-Pérez Leidy Patricia, Castañeda Miguel, Segura Daniel, Espín Guadalupe
Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, México.
PLoS One. 2015 Feb 2;10(2):e0117184. doi: 10.1371/journal.pone.0117184. eCollection 2015.
Upon encystment induction, Azotobacter vinelandii produces the phenolic lipids alkylresorcinols (ARs) that are structural components of the cysts. The enzymes responsible for the ARs synthesis are encoded in the arsABCD operon, whose expression is activated by ArpR. The transcription of arpR is initiated from an RpoS dependent promoter. The nitrogen-related phosphotransferase system (PTS(Ntr)) is a global regulatory system present in Gram negative bacteria. It comprises the EI(Ntr), NPr and EIIA(Ntr) proteins encoded by ptsP, ptsO and ptsN genes respectively. These proteins participate in a phosphoryl-group transfer from phosphoenolpyruvate to protein EIIA(Ntr) via the phosphotransferases EI(Ntr) and NPr. In A. vinelandii, the non-phosphorylated form of EIIA(Ntr) was previously shown to repress the synthesis of poly-ß-hydroxybutyrate. In this work, we show that PTS(Ntr) also regulates the synthesis of ARs. In a strain that carries unphosphorylated EIIA(Ntr), the expression of arpR was reduced, while synthesis of ARs and transcription of arsA were almost abrogated. The expression of arpR from an RpoS-independent promoter in this strain restored the ARs synthesis. Taken together these results indicate that unphosphorylated EIIA(Ntr) negatively affects activation of arpR transcription by RpoS.
在诱导形成孢囊时,棕色固氮菌会产生酚类脂质烷基间苯二酚(ARs),它们是孢囊的结构成分。负责ARs合成的酶由arsABCD操纵子编码,其表达由ArpR激活。arpR的转录从一个依赖RpoS的启动子开始。氮相关磷酸转移酶系统(PTS(Ntr))是革兰氏阴性细菌中存在的一种全局调节系统。它分别由ptsP、ptsO和ptsN基因编码的EI(Ntr)、NPr和EIIA(Ntr)蛋白组成。这些蛋白参与从磷酸烯醇丙酮酸通过磷酸转移酶EI(Ntr)和NPr向蛋白EIIA(Ntr)的磷酰基转移。在棕色固氮菌中,EIIA(Ntr)的非磷酸化形式先前已被证明可抑制聚-β-羟基丁酸酯的合成。在这项工作中,我们表明PTS(Ntr)也调节ARs的合成。在携带非磷酸化EIIA(Ntr)的菌株中,arpR的表达降低,而ARs的合成和arsA的转录几乎被消除。在该菌株中,从一个不依赖RpoS的启动子表达arpR恢复了ARs的合成。综合这些结果表明,非磷酸化的EIIA(Ntr)对RpoS激活arpR转录产生负面影响。