A molecular view by FTIR spectroscopy of the relationship between the antibiotic peptide lactocin 705 and membranes: speculations on antimicrobial

CASTELLANO PATRICIA; VIGNOLO GRACIELA; FARÍAS RICARDO; RODRÍGUEZ ARRONDO JOSÉ LUIS; CHEHÍN ROSANA

Buenos Aires- Argentina

Conferencia; ”. International Workshop on Infrared Spectroscopy Applied to Biological and Biomimetic Systems: From the Isolated Molecule to the Cell; 2007

Lactocin 705 is a bacteriocin whose activity depends upon the complementation of two peptides, termed Lac705a and Lac705b. Neither Lac705a nor Lac705b displayed bacteriocin activity by itself when the growth of sensitive cells was monitored. To obtain molecular insights into the lactocin 705 mechanism of action, Fourier transform infrared spectroscopy was used to investigate the interactions of each peptide (Lac705a and Lac705b) with dipalmitoylphosphatidylcholine liposomal membranes. Both peptides show ability to interact with zwitterionic membrane but at different bilayer levels. While Lac705á interacts with the interfacial region inducing dehydration, Lac705b peptide interacts only with the hydrophobic core. This paper presents the first experimental evidence that supports the hypothesis that Lac705a and Lac705b peptides could form a transmembrane oligomer. From the obtained results, a mechanism of action of lactocin 705 on membranes systems is proposed. The component Lac705á could induce dehydration of the bilayer interfacial region and Lac705â peptide could insert in the hydrophobic region of the membrane where the peptide has adequate conditions to achieve the oligomerization.