کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6291959 | 1302507 | 2011 | 7 صفحه PDF | دانلود رایگان |
Ecto-3â²-nucleotidase/nuclease (3â²NT/NU) is a membrane-bound enzyme that plays a key role in the nutrition of Leishmania sp. protozoan parasites. This enzyme generates nucleosides via hydrolyzes of 3â²mononucleotides and nucleic acids, which enter the cell by specific transporters. In this work, we identify and characterize Leishmania amazonensis ecto-3â²-nucleotidase activity (La3â²-nucleotidase), report ammonium tetrathiomolybdate (TTM) as a novel La3â²-nucleotidase inhibitor and approach the possible involvement of ecto-3â²-nucleotidase in cellular adhesion. La3â²-nucleotidase presented characteristics similar to those reported for the class I single-strand nuclease family; a molecular weight of approximately 40Â kDa and optimum activity in an alkaline pH range were observed. Although it is conserved among the genus, La3â²-nucleotidase displays different kinetic properties; it can be inhibited by vanadate, molybdate and Cu2+ ions. Interestingly, ecto-3â²-nucleotidase activity is 60-fold higher than that of ecto-5â²-nucleotidase in L. amazonensis. Additionally, ecto-3â²-nucleotidase activity is two-fold higher in virulent L. amazonensis cells than in avirulent ones. Notably, macrophage-parasite attachment/invasion was increased by 400% in the presence of adenosine 3â²-monophosphate (3â²AMP); however, this effect was reverted by TTM treatment. We believe that La3â²-nucleotidase may play a significant role in the generation of adenosine, which may contribute to mammalian host immune response impairment and establishment of infection.
Highlights⺠Promastigotes of Leishmania amazonensis hydrolyze 3â²AMP 60 times more than 5â²AMP. ⺠Ammonium tetratiomolybdate inhibits the ecto-3â²-nucleotidase of L. amazonensis. ⺠The macrophage-parasite interaction increased by 400% in presence of 3â²AMP. ⺠TTM prevents increased interaction observed in presence of 3â²AMP. ⺠Altogether, ecto-3â²nucleotidase could be involved on parasite-macrophage interaction.
Journal: Experimental Parasitology - Volume 129, Issue 3, November 2011, Pages 277-283