TY - JOUR
T1 - Ectopic expression of a Neospora caninum Kazal type inhibitor triggers developmental defects in Toxoplasma and Plasmodium
AU - Tampaki, Zoi
AU - Mwakubambanya, Ramadhan S.
AU - Goulielmaki, Evi
AU - Kaforou, Sofia
AU - Kim, Kami
AU - Waters, Andrew P.
AU - Carruthers, Vern B.
AU - Siden-Kiamos, Inga
AU - Loukeris, Thanasis G.
AU - Koussis, Konstantinos
N1 - Publisher Copyright:
© 2015 Tampaki et al.
PY - 2015/3/24
Y1 - 2015/3/24
N2 - Regulated proteolysis is known to control a variety of vital processes in apicomplexan parasites including invasion and egress of host cells. Serine proteases have been proposed as targets for drug development based upon inhibitor studies that show parasite attenuation and transmission blockage. Genetic studies suggest that serine proteases, such as subtilisin and rhomboid proteases, are essential but functional studies have proved challenging as active proteases are difficult to express. Proteinaceous Protease Inhibitors (PPIs) provide an alternative way to address the role of serine proteases in apicomplexan biology. To validate such an approach, a Neospora caninum Kazal inhibitor (NcPI-S) was expressed ectopically in two apicomplexan species, Toxoplasma gondii tachyzoites and Plasmodium berghei ookinetes, with the aim to disrupt proteolytic processes taking place within the secretory pathway. NcPI-S negatively affected proliferation of Toxoplasma tachyzoites, while it had no effect on invasion and egress. Expression of the inhibitor in P. berghei zygotes blocked their development into mature and invasive ookinetes. Moreover, ultra-structural studies indicated that expression of NcPI-S interfered with normal formation of micronemes, which was also confirmed by the lack of expression of the micronemal protein SOAP in these parasites. Our results suggest that NcPI-S could be a useful tool to investigate the function of proteases in processes fundamental for parasite survival, contributing to the effort to identify targets for parasite attenuation and transmission blockage.
AB - Regulated proteolysis is known to control a variety of vital processes in apicomplexan parasites including invasion and egress of host cells. Serine proteases have been proposed as targets for drug development based upon inhibitor studies that show parasite attenuation and transmission blockage. Genetic studies suggest that serine proteases, such as subtilisin and rhomboid proteases, are essential but functional studies have proved challenging as active proteases are difficult to express. Proteinaceous Protease Inhibitors (PPIs) provide an alternative way to address the role of serine proteases in apicomplexan biology. To validate such an approach, a Neospora caninum Kazal inhibitor (NcPI-S) was expressed ectopically in two apicomplexan species, Toxoplasma gondii tachyzoites and Plasmodium berghei ookinetes, with the aim to disrupt proteolytic processes taking place within the secretory pathway. NcPI-S negatively affected proliferation of Toxoplasma tachyzoites, while it had no effect on invasion and egress. Expression of the inhibitor in P. berghei zygotes blocked their development into mature and invasive ookinetes. Moreover, ultra-structural studies indicated that expression of NcPI-S interfered with normal formation of micronemes, which was also confirmed by the lack of expression of the micronemal protein SOAP in these parasites. Our results suggest that NcPI-S could be a useful tool to investigate the function of proteases in processes fundamental for parasite survival, contributing to the effort to identify targets for parasite attenuation and transmission blockage.
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U2 - 10.1371/journal.pone.0121379
DO - 10.1371/journal.pone.0121379
M3 - Article
C2 - 25803874
AN - SCOPUS:84925625559
SN - 1932-6203
VL - 10
JO - PloS one
JF - PloS one
IS - 3
M1 - e0121379
ER -