INVESTIGADORES
DUPUY Fernando Gabriel
congresos y reuniones científicas
Título:
An FTIR molecular view of the interaction between the antibiotic peptide Microcin J25 and membranes
Autor/es:
DUPUY F., CHEHÍN R. AND MORERO R.D.
Lugar:
Buenos Aires, Argentina
Reunión:
Workshop; International Workshop on Infrared Spectroscopy; 2007
Institución organizadora:
Cátedra de Química Inorgánica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires
Resumen:
Microcin J25 is
a 21 aminoacid peptide active against Escherichia coli and Salmonella
enteritidis strains. The MccJ25 structure is a nosse-like feature comprising a
ring formed by a N-terminus to Glu8
side-chain amide bond and a C-terminal tail which threads through the ring. Bacterial
transcription is inhibited by the binding of the peptide within the RNA
polymerase secondary channel, through which the substrates diffuse to the
enzyme active site.
However, the
peptide is capable of inhibit respiratory chain enzymes activity and bind to
model membranes also (1). A quantitative study of the partition of MccJ25 and
some analogous peptides into membranes was carried out with fluorescence
spectroscopy. Considering that MccJ25 is able to interact with biological
membranes, Fourier transform infrared spectroscopy (FTIR) was used to study the
conformational changes of the membrane as well as the peptide induced by the
interaction. This technique is known to be a versatile and powerful tool to
investigate changes that occur at different levels of the lipid bilayer, i.e, hydrophobic, interfacial and polar
regions (2). In this work, the obtained results shows that MccJ25 could not
induce dehydration of the bilayer interfacial region of
dipalmitoylphophatydilcholine (DPPC) bilayer. However, a strong perturbation in
the core of the bilayer is observed, suggesting that the peptide could insert
into the DPPC bilayer. As a consequence, the FTIR spectrum of the peptide
structure, evidenced by changes in the Amide I region, show changes. Bands at
around 1,625 cm-1, that have been associated with intramolecular
interactions (3), such as monomer-monomer contacts, increases in the presence
of DPPC liposomes. In the present communication, some evidence that could help
to understand the mechanism of action of
MccJ25 on the membrane is provided.