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Infect. Immun., Nov 1995, 4358-4367, Vol 63, No. 11
P Arhets, P Gounon, P Sansonetti and N Guillen
The redistribution and capping of surface receptors on the human pathogen
Entamoeba histolytica was observed in the presence of concanavalin A
(ConA). Capping was correlated with plasma membrane folding towards the
rear of the amoeba and with uroid formation. The uroid is thought to play a
role in the escape of amoebae from the host immune response. To localize
myosin II during capping, amoebae were incubated in the presence of ConA
and then analyzed by microscopy. Myosin II was three times more
concentrated within the uroid compared with the rest of the cell,
suggesting that the release of caps may depend upon mechanical contraction
driven by myosin II activity. The use of drugs that disrupt cytoskeletal
structure or that inhibit myosin heavy chain phosphorylation demonstrated
that inhibition of capping prevents uroid formation. Biochemical analysis
allowed the identification of two ConA receptors which have been previously
described as major pathogenic antigens of this parasite: the 96-kDa
antigen, which carries alcohol dehydrogenase 2 activity and binds
extracellular matrix proteins, and the Gal-GalNAc-inhibitable surface
lectin, which is involved in amoeba-cell interactions and in the
degradation of complement particles attached to the parasite.
Copyright © 1995, American Society for Microbiology
Myosin II is involved in capping and uroid formation in the human pathogen Entamoeba histolytica
Unite de Pathogenie Microbienne Moleculaire, Institut National de la Sante et de la Recherche Medicale U389, Paris, France.
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