Eylem Seç
Characterization of the Mechanism of Action of Fludioxonil, an Agricultural Antifungal
Başlık:
Characterization of the Mechanism of Action of Fludioxonil, an Agricultural Antifungal
Yazar:
Lawry, Stephanie Marie, author.
ISBN:
9780438159525
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (182 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-11(E), Section: B.
Advisors: Bruce S. Klein Committee members: David Andes; Katrina Forest; Bernard Weisblum; Jon Woods.
Özet:
Imagine a planet spoiled like moldy bread. Fungal infections now affect everything from biodiversity to human health. Consequently, antifungal compounds are needed to counteract these serious infections. Here, I describe my work characterizing the mode of action of the widely used agricultural antifungal fludioxonil. Fludioxonil requires group III hybrid histidine kinases (HHKs), such as Drk1 from Blastomyces dermatitidis, to mediate antifungal activity. Silencing Drk1 renders B. dermatitidis resistant to fludioxonil, whereas heterologous expression of Drk1 in Saccharomyces cerevisiae engenders fludioxonil sensitivity in this normally resistant yeast. Aside from requiring group III HHKs and the high osmolarity glycerol (HOG) pathway, the mechanism of action of fludioxonil is poorly understood. Using an in vivo phosphorylation assay, I discovered that fludioxonil caused Drk1 to convert from a kinase to a phosphatase and dephosphorylate its downstream phosphotransfer protein, Ypd1. This dephosphorylation is likely mediated through the Drk1 response regulator, or receiver, domain (Drk1R), since Drk1R can dephosphorylate Ypd1 in vitro in the absence of fludioxonil. Thus, Drk1R has intrinsic phosphatase activity when untethered from the Drk1 kinase domain. Despite observing a strong fludioxonil effect on Ypd1 phosphorylation in vivo in yeast, I could not detect the same response when I treated purified Drk1 and Ypd1 proteins with fludioxonil in vitro, suggesting fludioxonil does not act directly on Drk1 to alter its function.
Since my findings indicate fludioxonil likely does not directly target group III HHKs, as once originally thought, I investigated how and what Drk1 senses in vivo to modulate its activity. I found that Drk1 does respond to S-nitrosoglutathione and glutathione -- cysteine modifying small molecules -- in vitro to dephosphorylate Ypd1. Thus, these stress-like cell signals may incite in vivo action of fludioxonil. I also discovered that fludioxonil treatment of yeast likely induces oxidative stress in vivo and that a Drk1 cysteine 392 mutation increases resistance to fludioxonil. Since oxidative stress is often sensed through cysteine modification, Drk1 C392 may detect and respond to fludioxonil-induced oxidative stress. Overall, my work suggests that group III HHKs may be oxidative stress sensors, illustrating a novel function for this group of fungal kinases.
Notlar:
School code: 0262
Tüzel Kişi Ek Girişi:
Mevcut:*
Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(687893.1) | 687893-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
On Order
Liste seç
Bunu varsayılan liste yap.
Öğeler başarıyla eklendi
Öğeler eklenirken hata oldu. Lütfen tekrar deneyiniz.
:
Select An Item
Data usage warning: You will receive one text message for each title you selected.
Standard text messaging rates apply.