A sterol 14α-demethylase is required for conidiation, virulence and for mediating sensitivity to sterol demethylation inhibitors by the rice blast fungus Magnaporthe oryzae

Xia, Yan; Ma, Weibin; Li, Ya; Wang, Hong; Que, Yawei; Ma, Zhonghua; Talbot, Nicholas J.; Wang, Zhengyi

doi:10.1016/j.fgb.2010.09.005

Cited by 63 publications

(63 citation statements)

References 53 publications

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“…Miltefosine and antifungal azoles are known to alter lipid and sterol metabolism in Leishmania (19,20). It is conceivable that reduced expression of key sterol biosynthetic enzymes, such as CYP51 (sterol 14␣-demethylase, an antifungal azole target), would hypersensitize these organisms to the lethal effects of azoles, consistent with the earlier observations of enhanced sensitivity to antifungal azoles in CYP51 knockout fungi (21,22). Recently, a novel cytochrome P450, CYP5122A1, essential for survival, virulence, drug response, and ergosterol metabolism in Leishmania, was identified (14).…”

Section: Resultssupporting

confidence: 78%

“…While reduced expression of CYP51 has been shown to enhance the susceptibility to antifungal azoles in fungi (21,22), reduced expression of CYP5122A1 increased the sensitivity of L. donovani to miltefosine (14). Consistent with the hypothesis that resistance to DB766 was caused by altered expression of CYP5122A1 in L. donovani, Western blot analysis of these proteins indicated that expression of CYP5122A1 was dramatically reduced in the resistant organisms compared to that in their wildtype counterparts (Fig.…”

Section: Discussionsupporting

confidence: 61%

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Studies on the Antileishmanial Mechanism of Action of the Arylimidamide DB766: Azole Interactions and Role of CYP5122A1

Pandharkar

Zhu

Mathur

et al. 2014

Antimicrob Agents Chemother

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c Arylimidamides (AIAs) are inspired by diamidine antimicrobials but show superior activity against intracellular parasites. The AIA DB766 {2,5-bis[2-(2-i-propoxy)-4-(2-pyridylimino)aminophenyl]furan hydrochloride} displays outstanding potency against intracellular Leishmania parasites and is effective in murine and hamster models of visceral leishmaniasis when given orally, but its mechanism of action is unknown. In this study, through the use of continuous DB766 pressure, we raised Leishmania donovani axenic amastigotes that displayed 12-fold resistance to this compound. These DB766-resistant (DB766R) parasites were 2-fold more sensitive to miltefosine than wild-type organisms and were hypersensitive to the sterol 14␣-demethylase (CYP51) inhibitors ketoconazole and posaconazole (2,000-fold more sensitive and over 12,000-fold more sensitive than the wild type, respectively). Western blot analysis of DB766R parasites indicated that while expression of CYP51 is slightly increased in these organisms, expression of CYP5122A1, a recently identified cytochrome P450 associated with ergosterol metabolism in Leishmania, is dramatically reduced in DB766R parasites. In vitro susceptibility assays demonstrated that CYP5122A1 halfknockout L. donovani promastigotes were significantly less susceptible to DB766 and more susceptible to ketoconazole than their wild-type counterparts, consistent with observations in DB766R parasites. Further, DB766-posaconazole combinations displayed synergistic activity in both axenic and intracellular L. donovani amastigotes. Taken together, these studies implicate CYP5122A1 in the antileishmanial action of the AIAs and suggest that DB766-azole combinations are potential candidates for the development of synergistic antileishmanial therapy.

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Section: Resultssupporting

confidence: 78%

Section: Discussionsupporting

confidence: 61%

Studies on the Antileishmanial Mechanism of Action of the Arylimidamide DB766: Azole Interactions and Role of CYP5122A1

Pandharkar

Zhu

Mathur

et al. 2014

Antimicrob Agents Chemother

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“…2001), A. nidulans (Da Silva Ferreira et al 2005), and Magnaporthe oryzae (Yan et al 2011), and three in A. oryzae (Da Silva Ferreira et al 2005) and Fusarium spp. (Deng et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Paralog Re-Emergence: A Novel, Historically Contingent Mechanism in the Evolution of Antimicrobial Resistance

Hawkins

Cools

Sierotzki

et al. 2014

Molecular Biology and Evolution

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Evolution of resistance to drugs and pesticides poses a serious threat to human health and agricultural production. CYP51 encodes the target site of azole fungicides, widely used clinically and in agriculture. Azole resistance can evolve due to point mutations or overexpression of CYP51, and previous studies have shown that fungicide-resistant alleles have arisen by de novo mutation. Paralogs CYP51A and CYP51B are found in filamentous ascomycetes, but CYP51A has been lost from multiple lineages. Here, we show that in the barley pathogen Rhynchosporium commune, re-emergence of CYP51A constitutes a novel mechanism for the evolution of resistance to azoles. Pyrosequencing analysis of historical barley leaf samples from a unique long-term experiment from 1892 to 2008 indicates that the majority of the R. commune population lacked CYP51A until 1985, after which the frequency of CYP51A rapidly increased. Functional analysis demonstrates that CYP51A retains the same substrate as CYP51B, but with different transcriptional regulation. Phylogenetic analyses show that the origin of CYP51A far predates azole use, and newly sequenced Rhynchosporium genomes show CYP51A persisting in the R. commune lineage rather than being regained by horizontal gene transfer; therefore, CYP51A re-emergence provides an example of adaptation to novel compounds by selection from standing genetic variation.

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“…DMI-resistant isolates initially were thought to cause less disease than DMIsensitive isolates, suggesting that DMI resistance would not become widespread in field populations (11,13). However, established resistance to DMIs has been reported in many fungal pathogens (30,32,43), including C. beticola (1,23). DMIs are inhibitors of sterol P450 14a-demethylase (CYP51), a protein required for ergosterol biosynthesis in fungi (17).…”

mentioning

confidence: 99%

“…Fungicide sensitivity of field isolates can be measured by calculating 50% effective concentration (EC50) values (14,25,26,30,(37)(38)(39)43). The EC50 value is the concentration of fungicide in media that reduces fungal growth or spore germination by 50% compared with growth on nonamended media (38).…”

mentioning

confidence: 99%

Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

et al. 2012

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Bolton, M. D., Rivera-Varas, V., del Rio Mendoza, L. E., Khan, M. F. R., and Secor, G. A. 2012. Efficacy of variable tetraconazole rates against Cercospora beticola isolates with differing in vitro sensitivities to DMI fungicides. Plant Dis. 96:1749-1756.Cercospora leaf spot (CLS) of sugar beet is caused by the fungus Cercospora beticola. CLS management practices include the application of the sterol demethylation inhibitor (DMI) fungicides tetraconazole, difenoconazole, and prothioconazole. Evaluating resistance to DMIs is a major focus for CLS fungicide resistance management. Isolates were collected in 1997 and 1998 (baseline sensitivity to tetraconazole, prothioconazole, or difenoconazole) and 2007 through 2010 from the major sugar-beet-growing regions of Minnesota and North Dakota and assessed for in vitro sensitivity to two or three DMI fungicides. Most (47%) isolates collected in 1997-98 exhibited 50% effective concentration (EC50) values for tetraconazole of <0.01 (Jg ml"', whereas no isolates could be found in this EC50 range in 2010. Since 2007, annual median and mean tetraconazole EC50 values have generally been increasing, and the frequency of isolates with EC50 values >0.11 lig ml-' increased from 2008 to 2010. In contrast, the frequency of isolates with EC50 values for prothioconazole of >1.0 ng mh' has been decreasing since 2007. Annual median difenoconazole EC50 values appears to be stable, although annual mean EC50 values generally have been increasing for this fungicide. Although EC50 values are important for gauging fungicide sensitivity trends, a rigorous comparison of the relationship between in vitro EC50 values and loss of fungicide efficacy in planta has not been conducted for C. beticola. To explore this, 12 isolates exhibiting a wide range of tetraconazole EC50 values were inoculated to sugar beet but no tetraconazole was applied. No relationship was found between isolate EC50 value and disease severity. To assess whether EC50 values are related to fungicide efficacy in planta, sugar beet plants were sprayed with various dilutions of Eminent, the commercial formulation of tetraconazole, and subsequently inoculated with isolates that exhibited very low, medium, or high tetraconazole EC50 values. The high EC50 isolate caused significantly more disease than isolates with medium or very low EC50 values at the field application rate and most reduced rates. Because in vitro sensitivity testing is typically carried out with the active ingredient of the commercial fungicide, we investigated whether loss of disease control was the same for tetraconazole as for the commercial product Eminent. The high EC50 isolate caused more disease on plants treated with tetraconazole than Eminent but disease severity was not different between plants inoculated with the very low EC50 isolate.Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola (Sacc), is the most important foliar disease of sugar beet {Beta vulgaris L.) in North Dakota and Minnesota (39). The disease causes a reduction in root har...

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A sterol 14α-demethylase is required for conidiation, virulence and for mediating sensitivity to sterol demethylation inhibitors by the rice blast fungus Magnaporthe oryzae

Cited by 63 publications

References 53 publications

Studies on the Antileishmanial Mechanism of Action of the Arylimidamide DB766: Azole Interactions and Role of CYP5122A1

Studies on the Antileishmanial Mechanism of Action of the Arylimidamide DB766: Azole Interactions and Role of CYP5122A1

Paralog Re-Emergence: A Novel, Historically Contingent Mechanism in the Evolution of Antimicrobial Resistance

Efficacy of Variable Tetraconazole Rates Against Cercospora beticola Isolates with Differing In Vitro Sensitivities to DMI Fungicides

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