An acidic model pro-peptide affects the secondary structure, membrane interactions and antimicrobial activity of a crotalicidin fragment
Júnior, Nelson G.O. ; Cardoso, Marlon H. ; Cândido, Elizabete S. ; Broek, Danielle van den; Lange, Niek de; Velikova, Nadya ; Kleijn, J.M. ; Wells, Jerry M. ; Rezende, Taia M.B. ; Franco, Octávio Luiz ; Vries, Renko de - \ 2018
Scientific Reports 8 (2018)1. - ISSN 2045-2322
In order to study how acidic pro-peptides inhibit the antimicrobial activity of antimicrobial peptides, we introduce a simple model system, consisting of a 19 amino-acid long antimicrobial peptide, and an N-terminally attached, 10 amino-acid long acidic model pro-peptide. The antimicrobial peptide is a fragment of the crotalicidin peptide, a member of the cathelidin family, from rattlesnake venom. The model pro-peptide is a deca (glutamic acid). Attachment of the model pro-peptide only leads to a moderately large reduction in the binding to- and induced leakage of model liposomes, while the antimicrobial activity of the crotalicidin fragment is completely inhibited by attaching the model pro-peptide. Attaching the pro-peptide induces a conformational change to a more helical conformation, while there are no signs of intra- or intermolecular peptide complexation. We conclude that inhibition of antimicrobial activity by the model pro-peptide might be related to a conformational change induced by the pro-peptide domain, and that additional effects beyond induced changes in membrane activity must also be involved.
Specific in vitro toxicity of crude and refined petroleum products: 3. Estrogenic responses in mammalian assays
Vrabie, C.M. ; Candido, A. ; Berg, J.H.J. van den; Murk, A.J. ; Duursen, M. van; Jonker, M.T.O. - \ 2011
Environmental Toxicology and Chemistry 30 (2011)4. - ISSN 0730-7268 - p. 973 - 980.
cancer cell-line - receptor-mediated responses - mcf-7 cells - heavy oil - er-alpha - beta - proliferation - binding - model - chemicals
Current petroleum risk assessment considers only narcosis as the mode of action, but several studies have demonstrated that oils contain compounds with dioxin-like, estrogenic or antiestrogenic, and androgenic or antiandrogenic activities. The present study is the third in a series investigating the specific toxic effects of 11 crude oils and refined products. By employing recombinant mammalian cells stably transfected with the human estrogen receptor alpha (ERa) or beta (ERß), and expressing the luciferase protein (ERa-U2OS-Luc and ERß-U2OS-Luc assay), the estrogenicity or antiestrogenicity of oils was studied. All oils, except for two refined oils and one crude oil, induced estrogenic responses. The calculated estrogenic potencies of the oils were six to nine orders of magnitude lower than the potency of 17ß-estradiol (E2). Upon coexposure to a fixed concentration of E2 and increasing concentrations of oils, additive, antagonistic, and synergistic effects were revealed. One nautical fuel oil was tested in the human breast carcinoma cell line MCF-7, in which it induced cell proliferation up to 70% relative to the maximal induction by E2. At its minimum effect concentration of 25¿mg/L, the oil was also capable of inducing mRNA expression of the estrogen-dependent protein pS2 by a factor of two. The present results indicate that oils naturally contain potentially endocrine-disrupting compounds that are able to influence the estrogenicity of other compounds and may cause biological responses beyond receptor binding.