Action of the multifunctional peptide BP100 on native biomembranes examined by solid-state NMR

Abstract

Membrane composition is a key factor that regulates the destructive activity of antimicrobial peptides and the non-leaky permeation of cell penetrating peptides in vivo. Hence, the choice of model membrane is a crucial aspect in NMR studies and should reflect the biological situation as closely as possible. Here, we explore the structure and dynamics of the short multifunctional peptide BP100 using a multinuclear solid-state NMR approach. The membrane alignment and mobility of this 11 amino acid peptide was studied in various synthetic lipid bilayers with different net charge, fluidity, and thickness, as well as in native biomembranes harvested from prokaryotic and eukaryotic cells. (19)F-NMR provided the high sensitivity and lack of natural abundance background that are necessary to observe a labelled peptide even in protoplast membranes from Micrococcus luteus and in erythrocyte ghosts. Six selectively (19)F-labeled BP100 analogues gave remarkably similar spectra in all of the macroscopically oriented membrane systems, which were studied under quasi-native conditions of ambient temperature and full hydration. This similarity suggests that BP100 has the same surface-bound helical structure and high mobility in the different biomembranes and model membranes alike, independent of charge, thickness or cholesterol content of the system. (31)P-NMR spectra of the phospholipid components did not indicate any bilayer perturbation, so the formation of toroidal wormholes or micellarization can be excluded as a mechanism of its antimicrobial or cell penetrating action. However, (2)H-NMR analysis of the acyl chain order parameter profiles showed that BP100 leads to considerable membrane thinning and thereby local destabilization.

Membrane Thinning and Thickening Induced by Membrane-Active Amphipathic Peptides

“…Furthermore, both methods are compatible with oriented bilayer samples, which were used for three reasons. Firstly, this way the results of the present study can be directly related with our previous solid-state NMR measurements of the orientation of the selected peptides in mechanically oriented membranes (Salgado et al, 2001; Glaser et al, 2005; Grage et al, 2006; Tremouilhac et al, 2006; Afonin et al, 2008a,b, 2014; Strandberg et al, 2013; Wadhwani et al, 2014; Misiewicz et al, 2015a,b). Secondly, hydrated oriented samples provide a well-defined bilayer structure and morphology, with a uniform environment for the peptides.…”

“…Interestingly, exactly this set of peptides consisting of Mag2, GS, and BP100 are those peptides with the lowest propensity to tilt or insert into the membrane core amongst all the peptides studied here. BP100 does not adopt a tilted alignment (Wadhwani et al, 2014; Misiewicz et al, 2015a; Zamora-Carreras et al, 2016). Mag2 can change its alignment from a surface alignment to an obliquely tilted state only at very high peptide concentrations, but it has never been reported to insert any deeper into fluid bilayers (Strandberg et al, 2013).…”

“…Both GS and BP100 bind predominantly in an S-state alignment and possess a relatively high mobility as a consequence of their small size and compact shape (Salgado et al, 2001; Wadhwani et al, 2014; Zamora-Carreras et al, 2016). GS exhibits a low propensity for flipping into the membrane at high peptide:lipid ratio to form a putative oligomeric pore, which is only observed near the lipid phase transition temperature (Afonin et al, 2008b, 2014), whereas BP100 does not seem to undergo any concentration-dependent flip in its alignment (Misiewicz et al, 2015a). The behavior of these two short peptides, which are essentially located near the bilayer surface in an S-state, was contrasted in this study with yet another type of amphiphilic helical peptide.…”

Latarcins: versatile spider venom peptides

“…That the bacterial plasma membrane is a primary target of AMP became a dogma [93][94][95][96][97][98][99][100]. However, a necessity to switch from the studies of AMP in model membrane systems to their investigations on cells is becoming clear [101,102].…”

NMR studies of membrane proteins

“…The group of Ulrich (Misiewicz et al 2015) has addressed this issue by studying structure and dynamics of the peptide BP100 as a function of lipid composition. A large range of synthetic phospholipid bilayers was tested as well as membranes from erythrocytes and from the bacterium M. luteus.…”