Effects of antimycotic azoles on growth and sterol biosynthesis of Leishmania promastigotes

Dh, Beach; Lj, Goad; Holz, George G.

doi:10.1016/0166-6851(88)90166-1

Cited by 114 publications

(92 citation statements)

References 35 publications

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“…Although TBCYP51 profoundly prefers O of the four known substrates of sterol 14␣-demethylase (20), TCCYP51 demethylates this sterol very poorly (0.06 min Ϫ1 ) ( Table 2) analog N (which we tested as a potential substrate for trypanosomal CYP51 because it was listed among the sterols identified in vivo in Leishmania species (25,26)). However, the major differences in catalytic activity and binding parameters (M, D, and L versus O and N) are derived from the geometry surrounding the sterol C4 atom; both the equatorial (␣) and the angular (␤) methyl groups are strongly favored by TCCYP51.…”

Section: Substrate Preferences Of Tccyp51mentioning

confidence: 99%

CYP51 from Trypanosoma cruzi

Lepesheva

Zaitseva

Nes

et al. 2006

Journal of Biological Chemistry

118

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A potential drug target for treatment of Chagas disease, sterol 14␣-demethylase from Trypanosoma cruzi (TCCYP51), was found to be catalytically closely related to animal/fungi-like CYP51. Contrary to the ortholog from Trypanosoma brucei (TB), which like plant CYP51 requires C4-monomethylated sterol substrates, TCCYP51 prefers C4-dimethylsterols. Sixty-six CYP51 sequences are known from bacteria to human, their sequence homology ranging from ϳ25% between phyla to ϳ80% within a phylum. TC versus TB is the first example of two organisms from the same phylum, in which CYP51s (83% amino acid identity) have such profound differences in substrate specificity. Substitution of animal/fungi-like Ile 105 in the B helix to Phe, the residue found in this position in all plant and the other six CYP51 sequences from Trypanosomatidae, dramatically alters substrate preferences of TCCYP51, converting it into a more plant-like enzyme. The rates of 14␣-demethylation of obtusifoliol and its 24-demethyl analog 4␣-,4␣-dimethylcholesta-8,24-dien-3␤-ol(norlanosterol) increase 60-and 150-fold, respectively. Turnover of the three 4,4-dimethylated sterol substrates is reduced ϳ3.5-fold. These catalytic properties correlate with the sterol binding parameters, suggesting that Phe in this position provides necessary interactions with C4-monomethylated substrates, which Ile cannot. The CYP51 substrate preferences imply differences in the post-squalene portion of sterol biosynthesis in TC and TB. The phyla-specific residue can be used to predict preferred substrates of new CYP51 sequences and subsequently for the development of new artificial substrate analogs, which might serve as highly specific inhibitors able to kill human parasites.

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Section: Substrate Preferences Of Tccyp51mentioning

confidence: 99%

CYP51 from Trypanosoma cruzi

Lepesheva

Zaitseva

Nes

et al. 2006

Journal of Biological Chemistry

118

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“…To investi- gate whether the flagellar localization of SMP-1 is dependent on the lipid composition of the flagellar DRM, L. major promastigotes were treated with myriocin, an inhibitor of serine: palmitoyl-CoA transferase, the first committed enzyme in sphingolipid biosynthesis (Miyake et al, 1995) and ketoconazole, an inhibitor of sterol 14Ј-demethylase (Beach et al, 1988). At the concentrations used, these inhibitors cause a reduction of 70 and 50% in inositolphosphoceramide and sterol levels, respectively (Ginger et al, 2001;Ralton et al, 2002;our unpublished results).…”

Section: Flagellar Localization Of Smp-1 Is Not Affected By Changes Imentioning

confidence: 99%

SMP-1, a Member of a New Family of Small Myristoylated Proteins in Kinetoplastid Parasites, Is Targeted to the Flagellum Membrane inLeishmania

Tull

Vince

Callaghan

et al. 2004

MBoC

101

118

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The mechanisms by which proteins are targeted to the membrane of eukaryotic flagella and cilia are largely uncharacterized. We have identified a new family of small myristoylated proteins (SMPs) that are present in Leishmania spp and related trypanosomatid parasites. One of these proteins, termed SMP-1, is targeted to the Leishmania flagellum. SMP-1 is myristoylated and palmitoylated in vivo, and mutation of Gly-2 and Cys-3 residues showed that both fatty acids are required for flagellar localization. SMP-1 is associated with detergent-resistant membranes based on its recovery in the buoyant fraction after Triton X-100 extraction and sucrose density centrifugation and coextraction with the major surface glycolipids in Triton X-114. However, the flagellar localization of SMP-1 was not affected when sterol biosynthesis and the properties of detergent-resistant membranes were perturbed with ketoconazole. Remarkably, treatment of Leishmania with ketoconazole and myriocin (an inhibitor of sphingolipid biosynthesis) also had no affect on SMP-1 localization, despite causing the massive distension of the flagellum membrane and the partial or complete loss of internal axoneme and paraflagellar rod structures, respectively. These data suggest that flagellar membrane targeting of SMP-1 is not dependent on axonemal structures and that alterations in flagellar membrane lipid composition disrupt axoneme extension.

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“…The results from in vitro studies that have investigated the intrinsic differences in sensitivity of Leishmania species to sterol biosynthesis inhibitors have produced contradictory data. In a comparative study on the sensitivity of promastigotes to ketoconazole, L. donovani, L. braziliensis, and L. amazonensis were found to be more sensitive than L. aethiopica, L. major, L. tropica, and L. mexicana (11). However, in contrast, Rangel et al (122) observed that L. braziliensis was relatively insensitive to ketoconazole and the bistriazole D087, whereas L. mexicana was sensitive to ketoconazole.…”

Section: Azolesmentioning

confidence: 89%