Khosa Sakshi, Frieg Benedikt, Mulnaes Daniel, Kleinschrodt Diana, Hoeppner Astrid, Gohlke Holger, Smits Sander H J
Institute of Biochemistry, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
Sci Rep. 2016 Jan 4;6:18679. doi: 10.1038/srep18679.
Lantibiotics are potent antimicrobial peptides. Nisin is the most prominent member and contains five crucial lanthionine rings. Some clinically relevant bacteria express membrane-associated resistance proteins that proteolytically inactivate nisin. However, substrate recognition and specificity of these proteins is unknown. Here, we report the first three-dimensional structure of a nisin resistance protein from Streptococcus agalactiae (SaNSR) at 2.2 Å resolution. It contains an N-terminal helical bundle, and protease cap and core domains. The latter harbors the highly conserved TASSAEM region, which lies in a hydrophobic tunnel formed by all domains. By integrative modeling, mutagenesis studies, and genetic engineering of nisin variants, a model of the SaNSR/nisin complex is generated, revealing that SaNSR recognizes the last C-terminally located lanthionine ring of nisin. This determines the substrate specificity of SaNSR and ensures the exact coordination of the nisin cleavage site at the TASSAEM region.
羊毛硫抗生素是强效抗菌肽。乳链菌肽是最著名的成员，含有五个关键的羊毛硫氨酸环。一些临床相关细菌表达膜相关抗性蛋白，这些蛋白可通过蛋白水解作用使乳链菌肽失活。然而，这些蛋白的底物识别和特异性尚不清楚。在此，我们报告了无乳链球菌（SaNSR）的乳链菌肽抗性蛋白的首个三维结构，分辨率为2.2 Å。它包含一个N端螺旋束、蛋白酶帽和核心结构域。后者含有高度保守的TASSAEM区域，该区域位于由所有结构域形成的疏水通道中。通过整合建模、诱变研究和乳链菌肽变体的基因工程，生成了SaNSR/乳链菌肽复合物模型，揭示了SaNSR识别乳链菌肽最后一个位于C端的羊毛硫氨酸环。这决定了SaNSR的底物特异性，并确保了在TASSAEM区域乳链菌肽切割位点的精确配位。
