Analogs of squalene and oxidosqualene inhibit oxidosqualene cyclase of Trypanosoma cruzi expressed in Saccharomyces cerevisiae.
Recently, a number of inhibitors of the enzyme oxidosqualene cyclase (OSC; EC 5.4.99.7), a key enzyme in sterol biosynthesis, were shown to inhibit in mammalian cells the multiplication of Trypanosoma cruzi, the parasite agent of Chagas' disease. The gene coding for the OSC of T. cruzi has been cloned and expressed in Saccharomyces cerevisiae. The expression in yeast cells could be a safe and easy model for studying the activity and the selectivity of the potential inhibitors of T. cruzi OSC. Using a homogenate of S. cerevisiae cells expressing T. cruzi OSC, we have tested 19 inhibitors: aza, methylidene, vinyl sulfide, and conjugated vinyl sulfide derivatives of oxidosqualene and squalene, selected as representative of different classes of substrate analog inhibitors of OSC. The IC50 values of inhibition (the compound concentration at which the enzyme is inhibited by 50%) are compared with the values obtained using OSC of pig liver and S. cerevisiae. Many inhibitors of pig liver and S. cerevisiae OSC show comparable IC50 for T. cruzi OSC, but some phenylthiovinyl derivatives are 10-100 times more effective on the T. cruzi enzyme than on the pig or S. cerevisiae enzymes. The expression of proteins of pathogenic organisms in yeast seems very promising for preliminary screening of compounds that have potential therapeutic activity.
Dipartimento di Scienza e Tecnologia del Farmaco, Università di Torino, 10125 Turin, Italy.
Simonetta
S
Oliaro-Bosso
Maurizio
M
Ceruti
Gianni
G
Balliano
Paola
P
Milla
Flavio
F
Rocco
Franca
F
Viola
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017125:Genes, Protozoan; D019751:Intramolecular Transferases / Q000037:antagonists & inhibitors* / Q000235:genetics; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013185:Squalene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics
C002821:2,3-oxidosqualene; D004791:Enzyme Inhibitors; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D013185:Squalene; D019751:Intramolecular Transferases; C021924:lanosterol synthase