Lipid-binding and antimicrobial properties of synthetic peptides of bovine apolipoprotein A-II

Abstract

We previously showed that bovine apolipoprotein A-II (apoA-II) had antimicrobial activity against Escherichia coli and the yeast Saccharomyces cerevisiae in PBS. We have characterized here the active domain of apoA-II using synthetic peptides. A peptide corresponding to C-terminal residues Leu(49)-Thr(76) exhibited significant antimicrobial activity against E. coli in PBS, but not against S. cerevisiae. Experiments using amino-acid-substituted peptides indicated that the residues Phe(52)-Phe(53)-Lys(54)-Lys(55) are required for the activity. Peptide Leu(49)-Thr(76) induced the release of calcein trapped inside the vesicles whose lipid composition resembles that of E. coli membrane, suggesting that peptide Leu(49)-Thr(76) can destabilize the E. coli membrane. CD measurements showed that the alpha-helicity of peptide Leu(49)-Thr(76) increased from 3.5 to 36% by addition of the vesicles. When E. coli cells were incubated with peptide Leu(49)-Thr(76), some proteins were released to the external medium, probably owing to membrane destabilization caused by the peptide. In electron micrographs of E. coli cells treated with peptide Leu(49)-Thr(76), transparent nucleoids and granulated cytoplasm were observed. Amino acid substitutions, Phe(52)Phe(53)-->AlaAla (Phe(52, 53)-->Ala) in peptide Leu(49)-Thr(76) caused the loss of antimicrobial activity against E. coli, although protein-releasing activity was retained. Electron micrographs of the cells treated with peptide Leu(49)-Thr(76)(Phe(52,53)-->Ala) revealed morphological change only at the nucleoids. Therefore peptide Leu(49)-Thr(76) appears to primarily target the cytoplasm rather than the membrane of E. coli cells.

Modular determinants of antimicrobial activity in platelet factor-4 family kinocidins

“…The relative biochemical features of cPMP and its library peptides are summarized in Table 2. Molecular masses of the hemimers were comparable (4019 Da [N-terminal 1-37] versus 4166 Da [C-terminal]), as were masses of individual walkthrough 15-mer peptides (range, 1525 Da [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] to 1746 Da [60][61][62][63][64][65][66][67][68][69][70][71][72][73][74]). In contrast, electrostatic charge, steric bulk, and hydropathy varied among structural domains, and corresponded to native molecules.…”

Human Apolipoprotein E concentration in response to diseases and therapeutic treatments

“…Susceptible strains included Escherichia coli, Pseudomonas aeruginosa, Salmonella sp., Staphylococcus aureus (including methicillin-resistant isolates). In another recent study, Motizuki et al [1999] reported that bovine apoA-II peptide corresponding to residues Leu49-Thr76 also showed antibacterial activity and analysis of this peptide showed that it could form cationic amphipathic a-helices. Most apolipoproteins possess amphipathic-a helices and these structures have been shown to play an important role in protein-lipid and protein-protein interactions [Segrest et al, 1990].…”

Viper metalloproteinase (Agkistrodon halys pallas) with antimicrobial activity against multi‐drug resistant human pathogens

“…The structural changes induced by AHM on S. aureus, P. vulgaris, and P. mirabilis were studied using SEM as described earlier (Motizuki et al, 1999). Each 50 ml proteinase sample (7.5, 15, 30 mM) contained 1 ml of S. aureus, P. vulgaris, P. mirabilis, or B. pseudomallei (3.2 Â 10 6 CFU/ml) in MH broth incubated for 24 h at 378C.…”