The exact mechanism of interaction with membranes would depend

on whether the α-helical structures in cementoin are limited to those two α -helices proposed by AGADIR and chemical shifts or to a longer α -helix spanning residues 10-31 that would allow penetration of cementoin through the entire membrane width. Our diffusion data cannot discriminate between these different possibilities. Table 1 Diffusion Sapanisertib solubility dmso behavior of cementoin in H2O and bicelles. Experimental condition H2O DHPC DMPC1 cementoin (amide)2 cementoin (aliphatic)3 cementoin 25.22 – - 4.27 4.28 DHPC: DMPC: DMPG (8:3:1) 21.07 0.68 0.38 – - DHPC: DMPC: DMPG (8:3:1) + cementoin 21.08 0.97 0.61 1.25 1.23 Diffusion coefficients* are displayed for bicelles (DHPC + DMPC), H2O and cementoin in either of three experimental PD173074 research buy conditions in units of 10-6 cm2/s. * Calculated from AG = A0 exp[-(γδG)2 (Δ - δ/3) Ds ] 1 DMPG resonance was not observed and assumed to be overlapped with DMPC. 2 From an isolated resonance at 7.4 ppm. 3 Values are the average of three different resonances at

2.0, 2.1 and 3.0 ppm. Binding of pre-elafin/trappin-2 peptides to P. aeruginosa or artificial membranes Alvocidib datasheet does not cause extensive membrane disruption Positively charged α-helical peptides like cementoin, are characteristic of many AMPs. These were previously shown to either disrupt membranes and cause bacterial lysis or to translocate into the bacterial cytoplasm without causing cell lysis [19]. To obtain information about the mode of action of recombinant pheromone cementoin compared with that of elafin and pre-elafin/trappin-2 on P. aeruginosa, we first examined the effect of these peptides on bacteria by scanning electron micrography (SEM). As shown in Fig. 2, both elafin and cementoin significantly modified the appearance of P. aeruginosa cell surface

with clear evidence of wrinkling, blister formation and the presence of pore-like structures (white arrows in Fig. 2). At the same concentration, pre-elafin/trappin-2 appeared to affect less severely the bacterial morphology and cells harboring pore-like structures were much less abundant. The presence of pores suggests that membrane integrity is compromised by addition of these peptides. However, ghost cells were rarely observed. In sharp contrast, when P. aeruginosa were exposed to magainin 2, a lytic AMP, much fewer cells could be visualized by SEM and ghost cells were numerous indicating cell lysis (white arrowheads in Fig. 2). Figure 2 Scanning electron micrographs of P. aeruginosa incubated with cementoin, elafin, pre-elafin/trappin-2 or magainin 2. P. aeruginosa (~1 × 107 in 500 μL) were incubated 2 h with the indicated peptides before being processed for scanning electron microscopy as described in Methods. CNT; control performed in the absence of peptides, PE; pre-elafin/trappin-2, Cem; cementoin, Ela; elafin, Mag; magainin 2.