Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
Vol. 104, No. 2, 2009, pp. 281-289
Bioline Code: oc09045
Full paper language: English
Document type: Research Article
Document available free of charge
Memórias do Instituto Oswaldo Cruz, Vol. 104, No. 2, 2009, pp. 281-289
© Copyright 2009 - Instituto Oswaldo Cruz - Fiocruz
Oocyst wall formation and composition in coccidian parasites|
Mai, Kelly; Sharman, Philippa A.; Walker, Robert A.; Katrib, Marilyn; De Souza, David; McConville, Malcolm J.; Wallach, Michael G.; Belli, Sabina I.; Ferguson, David J.P. & Smith, Nicholas C.
The oocyst wall of coccidian parasites is a robust structure that is resistant to a variety of environmental and
chemical insults. This resilience allows oocysts to survive for long periods, facilitating transmission from host to
host. The wall is bilayered and is formed by the sequential release of the contents of two specialized organelles - wall
forming body 1 and wall forming body 2 - found in the macrogametocyte stage of Coccidia. The oocyst wall is over
90% protein but few of these proteins have been studied. One group is cysteine-rich and may be presumed to crosslink
via disulphide bridges, though this is yet to be investigated. Another group of wall proteins is rich in tyrosine.
These proteins, which range in size from 8-31 kDa, are derived from larger precursors of 56 and 82 kDa found in
the wall forming bodies. Proteases may catalyze processing of the precursors into tyrosine-rich peptides, which are
then oxidatively crosslinked in a reaction catalyzed by peroxidases. In support of this hypothesis, the oocyst wall has
high levels of dityrosine bonds. These dityrosine crosslinked proteins may provide a structural matrix for assembly
of the oocyst wall and contribute to its resilience.
Coccidia - oocyst - dityrosine crosslinking - Toxoplasma - Eimeria
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