Further Insights into Brevetoxin Metabolism by de Novo Radiolabeling

Toxins

Kevin Calabro²  Jean-Marie Guigonis⁴  Jean-Louis Teyssié¹  François Oberhänsli¹  Jean-Pierre Goudour³  Michel Warnau¹  Marie-Yasmine Dechraoui Bottein¹ 

[1]Radioecology Laboratory, International Atomic Energy Agency—Environment Laboratories, MC 98012, Monaco

[2] E-Mails:

[3]Institut de Chimie de Nice-PCRE (Processus Chimiques et Radiochimiques dans l’Environnement), UMR 7272 CNRS, Université de Nice Sophia-Antipolis, Faculté des Sciences, Parc Valrose Nice 06108, France

[4] E-Mail:

[5]Geoazur Laboratory, Université de Nice—Sophia-Antipolis, UMR 7329 CNRS, UR 082 IRD, Campus Azur CNRS Bât. 1, 250 rue Albert Einstein, Sophia Antipolis Valbonne 06560, France

[6] E-Mail:

[7]Plateforme “Bernard Rossi”—Laboratoire TIRO (Transporteur en Imagerie Radiothérapie et Oncologie), UMR E 4320 CEA /iBEB /SBTN-CAL, Université de Nice Sophia Antipolis, Faculté de Médecine, 28 Avenue de Valombrose, Nice 06107, France

[8] E-Mail:

关键词: Karenia brevis;    polyketide;    brevetoxins;    metabolism;    radiolabeling;   

DOI  :  10.3390/toxins6061785

来源: mdpi

【 摘 要 】

The toxic dinoflagellate Karenia brevis, responsible for early harmful algal blooms in the Gulf of Mexico, produces many secondary metabolites, including potent neurotoxins called brevetoxins (PbTx). These compounds have been identified as toxic agents for humans, and they are also responsible for the deaths of several marine organisms. The overall biosynthesis of these highly complex metabolites has not been fully ascertained, even if there is little doubt on a polyketide origin. In addition to gaining some insights into the metabolic events involved in the biosynthesis of these compounds, feeding studies with labeled precursors helps to discriminate between the de novo biosynthesis of toxins and conversion of stored intermediates into final toxic products in the response to environmental stresses. In this context, the use of radiolabeled precursors is well suited as it allows working with the highest sensitive techniques and consequently with a minor amount of cultured dinoflagellates. We were then able to incorporate [U-¹⁴C]-acetate, the renowned precursor of the polyketide pathway, in several PbTx produced by K. brevis. The specific activities of PbTx-1, -2, -3, and -7, identified by High-Resolution Electrospray Ionization Mass Spectrometer (HRESIMS), were assessed by HPLC-UV and highly sensitive Radio-TLC counting. We demonstrated that working at close to natural concentrations of acetate is a requirement for biosynthetic studies, highlighting the importance of highly sensitive radiolabeling feeding experiments. Quantification of the specific activity of the four, targeted toxins led us to propose that PbTx-1 and PbTx-2 aldehydes originate from oxidation of the primary alcohols of PbTx-7 and PbTx-3, respectively. This approach will open the way for a better comprehension of the metabolic pathways leading to PbTx but also to a better understanding of their regulation by environmental factors.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.