Wadhwani Parvesh, Strandberg Erik, van den Berg Jonas, Mink Christian, Bürck Jochen, Ciriello Raffaele A M, Ulrich Anne S
Karlsruhe Institute for Technology (KIT), Institute for Biological Interfaces (IBG-2), POB 3640, 76021 Karlsruhe, Germany.
KIT, Institute of Organic Chemistry and CFN, Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany.
Biochim Biophys Acta. 2014 Mar;1838(3):940-9. doi: 10.1016/j.bbamem.2013.11.001. Epub 2013 Nov 9.
BP100 is a multifunctional membrane-active peptide of only 11 amino acids, with a high antimicrobial activity, an efficient cell-penetrating ability, and low hemolytic side-effects. It forms an amphiphilic α-helix, similar to other antimicrobial peptides like magainin. However, BP100 is very short and thus unlikely to form membrane-spanning pores as proposed for longer peptides as a mechanism of action. We thus studied the conformation, membrane alignment and dynamical behavior of BP100 in lipid bilayers (DMPC/DMPG), using oriented circular dichroism (OCD) and solid-state (19)F and (15)N NMR. According to OCD and (15)N NMR, the BP100 helix is oriented roughly parallel to the membrane surface, but these methods yield no information on the azimuthal alignment angle or the dynamics of the molecule. To address these questions, a systematic (19)F NMR analysis was performed, which was not straightforward for this short peptide. Only a limited number of positions could be (19)F-labeled, all of which are located on one face of the helix, which was found to lead to artifacts in the data analysis. It was nevertheless possible to reconcile the (19)F NMR data with the OCD and (15)N NMR data by using an advanced dynamical model, in which peptide mobility is described by fluctuating tilt and azimuthal angles with Gaussian distributions. (19)F NMR thus confirmed the regular α-helical conformation of BP100, revealed its azimuthal angle, and described its high mobility in the membrane. Furthermore, the very sensitive (19)F NMR experiments showed that the alignment of BP100 does not vary with peptide concentration over a peptide-to-lipid molar ratio from 1:10 to 1:3000.
BP100是一种仅由11个氨基酸组成的多功能膜活性肽，具有高抗菌活性、高效的细胞穿透能力和低溶血副作用。它形成两亲性α螺旋，类似于其他抗菌肽如蛙皮素。然而，BP100非常短，因此不太可能像较长的肽那样通过形成跨膜孔作为作用机制。因此，我们使用取向圆二色性（OCD）以及固态（19）F和（15）N核磁共振研究了BP100在脂质双层（DMPC/DMPG）中的构象、膜排列和动力学行为。根据OCD和（15）N核磁共振，BP100螺旋大致平行于膜表面取向，但这些方法无法提供有关方位角排列角度或分子动力学的信息。为了解决这些问题，我们进行了系统的（19）F核磁共振分析，这对于这种短肽来说并非易事。只有有限数量的位置可以进行（19）F标记，所有这些位置都位于螺旋的一侧，结果发现这会导致数据分析中出现伪像。尽管如此，通过使用一种先进的动力学模型，仍有可能使（19）F核磁共振数据与OCD和（15）N核磁共振数据相协调，在该模型中，肽的流动性通过具有高斯分布的波动倾斜角和方位角来描述。（19）F核磁共振因此证实了BP100的规则α螺旋构象，揭示了其方位角，并描述了其在膜中的高流动性。此外，非常灵敏的（19）F核磁共振实验表明，在肽与脂质的摩尔比从1:10到1:3000的范围内，BP100的排列不随肽浓度而变化。
