Binding of Pediocin PA-1 with Anionic Lipid Induces Model Membrane Destabilization

Abstract

To obtain molecular insights into the action mode of antimicrobial activity of pediocin PA-1, the interactions between this bacteriocin and dimyristoylphosphatidylcholine (DMPC) or dimyristoylphosphatidylglycerol (DMPG) model membranes have been investigated in D 2 O at pD 6 by Fourier transform infrared spectroscopy. The interactions were monitored with respect to alteration of the secondary structure of pediocin, as registered by the amide I band, and phospholipid conformation, as revealed by the methylene s (CH 2 ) and carbonyl (CAO) stretching vibrations. The results show that no interaction between pediocin and DMPC occurs. By contrast, pediocin undergoes a structural reorganization in the presence of DMPG. Upon heating, pediocin self-aggregates, which is not observed for this pD in aqueous solution. The gel-to-crystalline phase transition of DMPG shifts to higher temperatures with a concomitant dehydration of the interfacial region. Our results indicate that pediocin is an extrinsic peptide and that its action mechanism may lie in a destabilization of the cell membrane.Pediocin PA-1 is a 44-amino-acid (molecular mass, 4,629 Da; pI, 9.6) (35) class IIa bacteriocin (38) produced by Pediococcus acidilactici PAC 1.0 and naturally found in fermented sausages (37) or other meat and vegetable fermentations (5). Its sequence is highly homologous to other class IIa bacteriocins (59). The N-terminal 20-amino-acid half of pediocin is in the majority of cases polar or cationic and highly conserved, with the consensus sequence Y3-G4-N5-G6-V7. The C-terminal half (residues A21 to C44) is much less polar and less conserved, containing a hypothetical hydrophobic membrane interaction domain. Two disulfide bonds stabilize the peptide structure, the one between the residues 24 and 44 accounting for its broad range of antimicrobial activity (17). Because of its specific antimicrobial activity against the foodborne psychrotrophic pathogen Listeria monocytogenes, pediocin PA-1 can potentially serve as a nontoxic food preservative to improve the quality, naturalness, and safety (55) of dairy and meat products.The data for Listeria innocua death induced by pediocin PA-1 reveal that its activity maximum is reached near pD 6 and decreases at pD 7 and 8 (15, 30). A relation between activity and structure alterations has not yet been completely established. The loss of activity as a function of pD seems to be associated to a structural reorganization and a decrease in the protein flexibility that in turn results in an irreversible aggregation upon heating (30). The C-terminal region is first involved in the aggregation process, resulting in a total inactivation of the protein (30). The N-terminal region participates in the aggregation process in a second step. Pediocin can exist in a soluble and hydrophobic structural form (16). In an aqueous environment, pediocin presents an unordered structure as seen by circular dichroism (75) and Fourier transform infrared (FTIR) spectroscopy (30), whereas upon adsorption to vesicles, a structura...

Regulation of Sterol Transport between Membranes and NPC2

“…The increase in T m indicates that binding of NPC2 leads to a stabilization of the gel phase and an increased level of ordering of the membrane phospholipids. Such behavior has been observed for a number of other surface-active proteins, including pediosin (53) and nisin (54). It is possible that the electrostatic interactions between NPC2 and acidic phospholipid headgroups may be stronger than lipid-lipid interactions (54).…”

Characterization and evaluation of whey protein-based biofilms as substrates for in vitro cell cultures

“…Molecular structure of whey protein-based biofilms FTIR was used to obtain detailed molecular information on the conformational behavior of whey proteins during the film-formation process and on the impact of plasticizers on film structure. This technique is a versatile, powerful method for determining the secondary structure of proteins in aqueous solutions [6,7], complex biological systems [21][22][23], and functional states [6,7,24]. Fig.…”

Antimicrobial Peptides with Unusual Amino Acid Compositions and Unusual Structures

“…These pediocins kill the target cells by membrane permeabilization and are characterized by the presence of several conserved Trp residues that are important determinants of their structure and activity [152]. The role of these Trp residues has recently been analyzed by individually and collectively mutating these Trp residues in a model pediocin, sakacin P, from the Lactobacillus sakei [153].…”

“…Pediocins are a group of bacteriocins of 37-48 residues produced by lactic acid bacteria Lactobacillus sakei Table 8 [151,152]. These pediocins kill the target cells by membrane permeabilization and are characterized by the presence of several conserved Trp residues that are important determinants of their structure and activity [152].…”