Structure and orientation of bovine lactoferrampin in the mimetic bacterial membrane as revealed by solid-state NMR and molecular dynamics simulation.
Bovine lactoferrampin (LFampinB) is a newly discovered antimicrobial peptide found in the N1-domain of bovine lactoferrin (268-284), and consists of 17 amino-acid residues. It is important to determine the orientation and structure of LFampinB in bacterial membranes to reveal the antimicrobial mechanism. We therefore performed (13)C and (31)P NMR, (13)C-(31)P rotational echo double resonance (REDOR), potassium ion-selective electrode, and quartz-crystal microbalance measurements for LFampinB with mimetic bacterial membrane and molecular-dynamics simulation in acidic membrane. (31)P NMR results indicated that LFampinB caused a defect in mimetic bacterial membranes. Ion-selective electrode measurements showed that ion leakage occurred for the mimetic bacterial membrane containing cardiolipin. Quartz-crystal microbalance measurements revealed that LFampinB had greater affinity to acidic phospholipids than that to neutral phospholipids. (13)C DD-MAS and static NMR spectra showed that LFampinB formed an α-helix in the N-terminus region and tilted 45° to the bilayer normal. REDOR dephasing patterns between carbonyl carbon nucleus in LFampinB and phosphorus nuclei in lipid phosphate groups were measured by (13)C-(31)P REDOR and the results revealed that LFampinB is located in the interfacial region of the membrane. Molecular-dynamics simulation showed the tilt angle to be 42° and the rotation angle to be 92.5° for Leu(3), which are in excellent agreement with the experimental values.
Graduate School of Engineering, Yokohama National University, Yokohama, Kanagawa, Japan.
Atsushi
A
Tsutsumi
Namsrai
N
Javkhlantugs
Atsushi
A
Kira
Masako
M
Umeyama
Izuru
I
Kawamura
Katsuyuki
K
Nishimura
Kazuyoshi
K
Ueda
Akira
A
Naito
D020816:Amino Acid Motifs; D002308:Cardiolipins / Q000737:chemistry; D017736:Ion-Selective Electrodes; D007781:Lactoferrin / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry*
D002308:Cardiolipins; D010446:Peptide Fragments; D053835:Unilamellar Liposomes; C502040:lactoferrampin; D007781:Lactoferrin