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STRUCTURAL STUDIES OF THE ANTIMICROBIAL PEPTIDE TRITRPTICIN (TRP3) by NMR
LoSan, T.1*;Schreier, S.2; Nakaie, C3.; Almeida, F. C. L.1; Valente, A. P.1
1-
Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto
de Bioquímica Médica, Universidade Federal do Rio de Janeiro-Rio de
Janeiro-RJ; 2 – Universidade de São Paulo, USP, São Paulo-SP; 3- Universidade Federal do Estado de São Paulo, UNIFESP, São Paulo-SP
Antimicrobial
peptides are widespread in nature and correspond to a powerful defense
against pathogens. Currently, its study gained great importance due to
resistant of microorganisms to conventional antibiotics. In mammals
diverse existing families of antimicrobial peptides were characterized.
Among them the catelicidin is one best studied. Tritrpticin (TRP3)
belongs to this family and are synthesized in the mieloid glands cells
of mammals and secreted in the inflammation plates. TRP3
is cationic and rich in Arg, Pro and three Trp. Its primary structure
is composed for 13 amino acids (VRRFPWWWPFLRR) and presents an almost
palindromic sequence. TRP3 has antimicrobial activity against a wide
range of fungi, gram-negative and gram-positive bacteria. Its proposed
mechanism consists in membrane binding and disruption. This work aims
at to compare the already published structure in SDS (1) with the
multiple conformers found in water, TFE (2,2,2 trifluoroethanol) and
phospholipid vesicles. This data can help to correlate the wide range
of antimicrobial activity observed for TRP3 and its malleability in
different media. Our results demonstrate that the multiple
conformations observed in water are stable and interchangeable. The
spectra in water have several similarities with the one observed in
SDS. Several amino acids have the same chemical shift and could be
assigned. Unfortunately the NOESY and ROESY spectra gave no
inter-residue cross-peaks, due to chemical exchange between structures,
impeding full resonance assignment for each conformer. The use of the
TFE 40% concentration could stabilize one conformer. Remarkably, that
conformer has also similarities with the one observed in SDS. The use
of specific saturation experiments will help to assign the peptide in
water. Similar experiments will be performed in the presence of DPC and
phospholipids vesicles. The similarity in structure in all different
media will help to correlate the relationship between structure and
function. 1.
SCHIBLI, D.J.; HWANG, P.M. and VOGEL, H.J. Structure of the
Antimicrobial Peptide Tritrpticin Bound to Micelles: A Distinct
Membrane-Bound Peptide Fold. Biochemistry 1999, 38, 16749-16755.
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