The Journal of Cell Biology, Vol 71, 23-34, Copyright © 1976 by The Rockefeller University Press

ARTICLES

The microsporidian spore invasion tube. The ultrastructure, isolation, and characterization of the protein comprising the tube

E Weidner

The extrusion apparatus of the microsporidian parasitic protozoan Nosema michaelis discharges an invasion (or polar) tube with a velocity suitalbe for piercing cells and injecting infective sporoplasm. The tube is composed of a polar tube protein (PTP) which consists of a single, low molecular weight polypeptide slightly smaller than chymotrypsinogen-A. Assembled PTP tubes resist dissociation in sodium dodecyl sulfate and brief exposures in media at extreme ends of the pH range; however, the tubes are reduced by mercaptoethanol and dithiothreitol. When acidified, mercaptoethanol-reduced PTP self- assembles into plastic, two-dimensional monolayers. Dithiothreitol- reduced PTP will not reassemble when acidified. Evidence is presented which indicates that PTP is assembled as a tube within the spore; that the ejected tube has plasticity during sporoplasm passage; and, finally, that the subunits within the tube polymer are bound together, in part, by interprotein disulfide linkages.
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This article has been cited by other articles:

• Xu, Y., Takvorian, P. M., Cali, A., Orr, G., Weiss, L. M. (2004). Glycosylation of the Major Polar Tube Protein of Encephalitozoon hellem, a Microsporidian Parasite That Infects Humans. Infect. Immun. 72: 6341-6350 [Abstract] [Full Text]  
• Delbac, F., Peuvel, I., Metenier, G., Peyretaillade, E., Vivares, C. P. (2001). Microsporidian Invasion Apparatus: Identification of a Novel Polar Tube Protein and Evidence for Clustering of ptp1 and ptp2 Genes in Three Encephalitozoon Species. Infect. Immun. 69: 1016-1024 [Abstract] [Full Text]  

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