2WV2 image
Entry Detail
PDB ID:
2WV2
Keywords:
Title:
X-ray structure of CYP51 from the human pathogen Trypanosoma brucei in complex with fluconazole
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2009-10-12
Release Date:
2009-11-10
Method Details:
Experimental Method:
Resolution:
2.70 Å
R-Value Free:
0.27
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
P 31 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:LANOSTEROL 14-ALPHA-DEMETHYLASE
Chain IDs:A
Chain Length:475
Number of Molecules:1
Biological Source:TRYPANOSOMA BRUCEI
Primary Citation
Structural Characterization of Cyp51 from Trypanosoma Cruzi and Trypanosoma Brucei Bound to the Antifungal Drugs Posaconazole and Fluconazole
Plos Negl Trop Dis 4 E651 ? (2010)
PMID: 20386598 DOI: 10.1371/JOURNAL.PNTD.0000651

Abstact

BACKGROUND Chagas Disease is the leading cause of heart failure in Latin America. Current drug therapy is limited by issues of both efficacy and severe side effects. Trypansoma cruzi, the protozoan agent of Chagas Disease, is closely related to two other major global pathogens, Leishmania spp., responsible for leishmaniasis, and Trypansoma brucei, the causative agent of African Sleeping Sickness. Both T. cruzi and Leishmania parasites have an essential requirement for ergosterol, and are thus vulnerable to inhibitors of sterol 14alpha-demethylase (CYP51), which catalyzes the conversion of lanosterol to ergosterol. Clinically employed anti-fungal azoles inhibit ergosterol biosynthesis in fungi, and specific azoles are also effective against both Trypanosoma and Leishmania parasites. However, modification of azoles to enhance efficacy and circumvent potential drug resistance has been problematic for both parasitic and fungal infections due to the lack of structural insights into drug binding. METHODOLOGY/PRINCIPAL FINDINGS We have determined the crystal structures for CYP51 from T. cruzi (resolutions of 2.35 A and 2.27 A), and from the related pathogen T. brucei (resolutions of 2.7 A and 2.6 A), co-crystallized with the antifungal drugs fluconazole and posaconazole. Remarkably, both drugs adopt multiple conformations when binding the target. The fluconazole 2,4-difluorophenyl ring flips 180 degrees depending on the H-bonding interactions with the BC-loop. The terminus of the long functional tail group of posaconazole is bound loosely in the mouth of the hydrophobic substrate binding tunnel, suggesting that the major contribution of the tail to drug efficacy is for pharmacokinetics rather than in interactions with the target. CONCLUSIONS/SIGNIFICANCE The structures provide new insights into binding of azoles to CYP51 and mechanisms of potential drug resistance. Our studies define in structural detail the CYP51 therapeutic target in T. cruzi, and offer a starting point for rationally designed anti-Chagasic drugs with improved efficacy and reduced toxicity.

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