A protein phosphatase 1 gamma ( PP 1 c ) of the human protozoan parasite Trichomonas vaginalis is involved in proliferation and cell attachment to the host cell q

In this work, evidence for a critical role of Trichomonas vaginalis protein phosphatase 1 gamma (TvPP1c) in proliferation and attachment of the parasite to the mammalian cell is provided. Firstly, proliferation and attachment of T. vaginalis parasites to HeLa cells was blocked by calyculin A (CA), a potent PP1 inhibitor. Secondly, it was demonstrated that the enzyme activity of native and recombinant TvPP1c proteins was inhibited by CA. Thirdly, reverse genetic studies confirmed that antisense oligonucleotides targeted to PP1c but not PP1a or b inhibited proliferation and attachment of trichomonads CA-treated parasites underwent cytoskeletal modifications, including a lack of axostyle typical labelling, suggesting that cytoskeletal phosphorylation could be regulated by a CA-sensitive phosphatase where the role of PP1c could not be ruled out. Analysis of subcellular distribution of TvPP1c by cell fractionation and electron microscopy demonstrated the association between TvPP1c and the cytoskeleton. The expression of adhesins, AP120 and AP65, at the cell surface was also inhibited by CA. The concomitant inhibition of expression of adhesins and changes in the cytoskeleton in CA-treated parasites suggest a specific role for PP1c dependent dephosphorylation in the early stages of the host-parasite interaction. Molecular modelling of TvPP1c showed the conservation of residues critical for maintaining proper folding into the gross structure common to PP1 proteins. Taken together, these results suggest that TvPP1c could be considered a potential novel drug target for treatment of trichomoniasis. 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.