Khosa Sakshi, Hoeppner Astrid, Kleinschrodt Diana, Smits Sander H J
Institute of Biochemistry, Heinrich-Heine-University, 40225 Düsseldorf, Germany.
Crystal Farm and X-ray Facility, Heinrich-Heine-University, 40225 Düsseldorf, Germany.
Acta Crystallogr F Struct Biol Commun. 2015 Jun;71(Pt 6):671-5. doi: 10.1107/S2053230X15006226. Epub 2015 May 20.
Nisin is a 34-amino-acid antimicrobial peptide produced by Lactococcus lactis belonging to the class of lantibiotics. Nisin displays a high bactericidal activity against various Gram-positive bacteria, including some human-pathogenic strains. However, there are some nisin-non-producing strains that are naturally resistant owing to the presence of the nsr gene within their genome. The encoded protein, NSR, cleaves off the last six amino acids of nisin, thereby reducing its bactericidal efficacy. An expression and purification protocol has been established for the NSR protein from Streptococcus agalactiae COH1. The protein was successfully crystallized using the vapour-diffusion method in hanging and sitting drops, resulting in crystals that diffracted X-rays to 2.8 and 2.2 Å, respectively.
乳链菌肽是一种由乳酸乳球菌产生的34个氨基酸的抗菌肽，属于羊毛硫抗生素类。乳链菌肽对各种革兰氏阳性菌，包括一些人类致病菌株，具有很高的杀菌活性。然而，由于其基因组中存在nsr基因，一些不产生乳链菌肽的菌株天然具有抗性。编码的蛋白质NSR会切割掉乳链菌肽的最后六个氨基酸，从而降低其杀菌效力。已经建立了一种从无乳链球菌COH1中表达和纯化NSR蛋白的方案。该蛋白通过悬滴法和坐滴法的气相扩散法成功结晶，分别得到了X射线衍射分辨率为2.8 Å和2.2 Å的晶体。
