Naslov
Aflatoxin biosynthesis in Aspergilus parasiticus: a role for yap-1 like gene

Autori
Fabbri, Anna A. ; Fanelli, Corrado ; Ricelli, Alessandra ; Zjalic, Slaven ; Fabbri, Claudia ; Reverberi, Massimo

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
8th Europeean Conference on Fungal Genetics. Book of abstracts / - , 2006, 220-220

Skup
8th Europeean Conference on Fungal Genetics.

Mjesto i datum
Beč, Austrija, 08.04.2006. - 11.04.2006

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
aflatoxins; lipoperoxides; reactive oxygen species; yap-1 like gene; skn7-like gene; antioxidants
(aflatoxins; lipoperoxides; reactigve oxygen species; yap-1 like gene; skn7-like gene; antioxidants)

Sažetak
It has been established that lipoperoxide formation in Aspergillus parasiticus promotes aflatoxin biosynthesis in conducive and low conducive media (Potato Dextrose Broth and Czapek Broth, respectively). In low-conducive medium oxidative stress was induced by addition of comene hydroperoxide (1mM), a lipoperoxidation inducer. The two regioisomers of linoleic acid hydroperoxides (9-HODE and 13-HODE) were analysed in A. parasiticus mycelia grownin both media with and without cumene hydroperoxyde addition, by liquid chromatography-mas spectrometry (LC-MS). The addition to the conducive and low conducive media of phenolic antioxidants inhibits aflatoxin synthesis of about 80-90% furtherly supporting the role played by lipoperoxidation in aflatoxin formation. The activation of some oxidative stress related transcription factors such as yap1-like, skn7-like and hsf2-like appears to drive the correlation between oxidative stress in the mycelia and aflatoxin production in the cells as well as activities of antioxidant enzymes superoxide dismutase (SOD) and glutathion peroxidase (GPX). In Sacharomyces cervisiae Yap1 coordinates the respons to oxidative stress probably by acting as a sensor of oxidation by a cysteine-rich domain that readily undergoes oxidation in the presence of lipoperoxides another reactive oxygen species in fungal cell. The inhibition of aflatoxin biosynthesis that occurs when antioxidants are added to the media could be related to enhancement of the oxidative stress related transcription factors like yap1-like that in turn lead to the enhancement of the activity of SOD and GPX. Yap1-like gene fragment was inactivated in A. parasiticus strain NRRL2999 by homologous recombination with the plasmid p3SR2 in which was inserted fragment of yap1-like like sequences. The mutant ApDyap1-like inoculated in aflatoxin conducive media advanced and increased aflatoxin biosynthesis in comparison with wild type. This result suggests that the delletion of yap1-like alters the fungal defence response against oxidative stress thus settling a cell environment proner to support an earlier toxin formation. In conclusion reactive species like as lipoperoxides create a stressing environment that fungal cell tries to control by activating oxidative stress related transcription factors and antioxidant enzymes. In this context yap1-like appears to play a modulating role in the metabolic events that lead to aflatoxin biosynthesis.

Izvorni jezik
Engleski

Znanstvena područja
Biologija, Biotehnologija

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