Peschel A, Schnell N, Hille M, Entian K D, Götz F
Mikrobielle Genetik, Universität Tübingen, Germany.
Mol Gen Genet. 1997 Apr 16;254(3):312-8. doi: 10.1007/s004380050421.
The closely related lantibiotics epidermin and gallidermin are produced by Staphylococcus epidermidis Tu3298 and S. gallinarum Tu3928, respectively. The epidermin biosynthetic genes involved in maturation, regulation, and immunity have been identified previously. How epidermin or gallidermin is secreted, however, has remained unclear. Here, we characterize two additional genes, epiH and epiT, as well as the homologous gallidermin genes gdmH and gdmT. EpiT and GdmT are similar to one-component ABC transporters that are involved in the secretion of proteins or peptides. EpiH and GdmH are hydrophobic proteins without conspicuous similarities to other proteins. Comparison of the gene sequences revealed that epiT is incomplete, having an internal deletion that causes a frame shift and a second deletion at the 3'-end, while gdmT is intact. Introduction of epiT and epiH into the heterologous host S. carnosus (pTepi14) bearing the maturation and regulation genes had no significant effect on the rather low level of epidermin production. The presence of the homologous gdmT and gdmH, however, resulted in a strong increase (seven- to tenfold) in the production level, which is very likely to be due to increased efficiency of epidermin secretion. Both gdmT and gdmH were necessary for this effect, indicating that the two gene products cooperate in some way. In the epidermin-producing wild-type strain Tu3298, which contains epiH and the disrupted epiT, the addition of gdmT alone led to a two-fold increase in epidermin production. Both gdmT and gdmH and the corresponding epi genes were activated by the transcriptional regulator EpiQ; this is in accordance with the presence of putative EpiQ operator sites in the promoter regions.
密切相关的羊毛硫抗生素表皮菌素和鸡表皮菌素分别由表皮葡萄球菌Tu3298和鸡葡萄球菌Tu3928产生。先前已鉴定出参与成熟、调控和免疫的表皮菌素生物合成基因。然而，表皮菌素或鸡表皮菌素是如何分泌的仍不清楚。在这里，我们鉴定了另外两个基因epiH和epiT，以及同源的鸡表皮菌素基因gdmH和gdmT。EpiT和GdmT类似于参与蛋白质或肽分泌的单组分ABC转运蛋白。EpiH和GdmH是疏水蛋白，与其他蛋白没有明显的相似性。基因序列比较显示epiT不完整，有一个内部缺失导致移码，3'-端还有第二个缺失，而gdmT是完整的。将epiT和epiH导入携带成熟和调控基因的异源宿主肉葡萄球菌（pTepi14）中，对相当低水平的表皮菌素产生没有显著影响。然而，同源的gdmT和gdmH的存在导致产生水平大幅提高（七至十倍），这很可能是由于表皮菌素分泌效率提高所致。gdmT和gdmH对这种效应都是必需的，表明这两种基因产物以某种方式协同作用。在产生表皮菌素的野生型菌株Tu3298中，其含有epiH和被破坏的epiT，单独添加gdmT导致表皮菌素产量增加两倍。gdmT和gdmH以及相应的epi基因均由转录调节因子EpiQ激活；这与启动子区域中存在假定的EpiQ操纵位点一致。
