Pentamidine is an antiparasitic and apoptotic drug that selectively modifies ubiquitin.
We have determined the cytotoxic properties of pentamidine isethionate (2) towards the promastigotes of the protozoan parasite Leishmania infantum. The leishmanicidal activity of 2 was 60 times higher after 72 h of incubation than that of cisplatin (4). The pentamidine salt 2 induced a higher amount of programmed cell death (PCD) than cisplatin, which is associated with inhibition of DNA synthesis and cell-cycle arrest in the G2/M phase. Circular dichroism (CD) data indicate that binding of 2 to calf-thymus DNA (CT-DNA) induces conformational changes in the DNA double helix, consistent with a B-->A transition. Moreover, the interaction of 2 with ubiquitin led to a 6% increase in the beta-sheet content of the protein as observed by CD spectroscopy. Fluorescence-spectroscopy studies agreed with the CD data, showing that the pentamidine portion of 2 induces a significant decrease in the fluorescence of the Ub residues Phe4 and Phe45 located on the beta-cluster of the molecule, but not of Tyr59 on the alpha-cluster. These data indicate that pentamidine specifically modifies the beta-cluster, i.e., the 'basic face' of ubiquitin. Our results suggest that the biochemical mechanism of action of pentamidine may be a consequence of its dual binding to DNA and proteins.
Nguewa
Paul A
PA
Departamento de Parasitología, Facultad de Farmacia, Universidad de la Laguna Tenerife, Spain.
Fuertes
Miguel A
MA
Cepeda
Victoria
V
Iborra
Salvador
S
Carrión
Javier
J
Valladares
Basilio
B
Alonso
Carlos
C
Pérez
José M
JM
D000595:Amino Acid Sequence; D000818:Animals; D000981:Antiprotozoal Agents / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D018314:Leishmania infantum / Q000187:drug effects; D008958:Models, Molecular; D015394:Molecular Structure; D010419:Pentamidine / Q000737:chemistry* / Q000494:pharmacology*; D011485:Protein Binding; D025801:Ubiquitin / Q000737:chemistry*
D000981:Antiprotozoal Agents; D025801:Ubiquitin; D010419:Pentamidine