Ectopic expression of a Neospora caninum Kazal type inhibitor triggers developmental defects in Toxoplasma and Plasmodium

Tampaki, Z., Mwakubambanya, R. S., Goulielmaki, E., Kaforou, S., Kim, K., Waters, A. P. , Carruthers, V. B., Siden-Kiamos, I., Loukeris, T. G. and Koussis, K. (2015) Ectopic expression of a Neospora caninum Kazal type inhibitor triggers developmental defects in Toxoplasma and Plasmodium. PLoS ONE, 10(3), e0121379. (doi:10.1371/journal.pone.0121379) (PMID:25803874) (PMCID:PMC4372514)

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Abstract

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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Waters, Professor Andy
Authors: Tampaki, Z., Mwakubambanya, R. S., Goulielmaki, E., Kaforou, S., Kim, K., Waters, A. P., Carruthers, V. B., Siden-Kiamos, I., Loukeris, T. G., and Koussis, K.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:PLoS ONE
Publisher:Public Library of Science
ISSN:1932-6203
ISSN (Online):1932-6203
Copyright Holders:Copyright © 2015 The Authors
First Published:First published in PLoS ONE 10(3):e0121379
Publisher Policy:Reproduced under a Creative Commons License

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