Corsini Gino, Baeza Marcelo, Monasterio Octavio, Lagos Rosalba
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
Biochimie. 2002 May-Jun;84(5-6):539-44. doi: 10.1016/s0300-9084(02)01415-3.
The production of active microcin E492, a channel-forming bacteriocin, was studied in exponential and stationary phase. The structural gene for this bacteriocin (mceA) is transcribed in exponential as well as in stationary phase, but the active form is produced only during the exponential phase of growth. An inactive form of microcin E492 was purified from the stationary phase. The production of the inactive form correlated with the lack of transcription in the stationary phase of two genes (mceIJ) involved in microcin E492 maturation, consequently behaving as the inactive form purified from mutants in these genes. The inactive form of microcin purified from the stationary phase as well as the inactive form purified from mutants in the maturation genes (mceC, I, J) were unable to compete with the active form when tested using a viability test on sensitive cells. This result strongly suggests that the inactive form of microcin caused by the lack of expression of the maturation genes is impaired at the level of receptor recognition.
我们研究了形成通道的细菌素活性微菌素E492在指数生长期和稳定期的产生情况。这种细菌素的结构基因（mceA）在指数生长期和稳定期均有转录，但活性形式仅在生长的指数期产生。从稳定期纯化出了微菌素E492的无活性形式。无活性形式的产生与参与微菌素E492成熟的两个基因（mceIJ）在稳定期缺乏转录相关，因此其表现与从这些基因的突变体中纯化出的无活性形式相同。当使用对敏感细胞的活力测试进行检测时，从稳定期纯化出的微菌素无活性形式以及从成熟基因（mceC、I、J）突变体中纯化出的无活性形式均无法与活性形式竞争。这一结果强烈表明，由成熟基因表达缺失导致的微菌素无活性形式在受体识别水平上存在缺陷。
