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Infection and Immunity, May 2000, p. 2930-2938, Vol. 68, No. 5
Department of Molecular Biology and
Microbiology, Tufts University School of
Medicine,1 and Howard Hughes Medical
Institute,3 Boston, Massachusetts 02111, and
Institute of Microbiology, Freie Universität, 14195 Berlin, Germany2
Received 30 November 1999/Returned for modification 7 January
2000/Accepted 27 January 2000
The binding of the Yersinia pseudotuberculosis and
Yersinia enterocolitica invasin proteins to
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
An Immunoglobulin Superfamily-Like Domain Unique to
the Yersinia pseudotuberculosis Invasin Protein Is Required
for Stimulation of Bacterial Uptake via Integrin Receptors
1 integrin receptors allows internalization of these
organisms by cultured cells. The C-terminal 192-residue superdomain of
the Y. pseudotuberculosis invasin is necessary and
sufficient for integrin recognition, while a region located outside,
and N-terminal to, this superdomain strongly enhances the efficiency of
bacterial uptake. Within the enhancer region is a domain called D2 that
allows invasin-invasin interaction. To investigate the role of the
enhancer region, bacterial cell binding and entry mediated by the
Y. pseudotuberculosis invasin protein
(invasinpstb) was compared to that of Y. enterocolitica invasin (invasinent),
which lacks the D2 self-association domain.
Invasinent was shown to be unable to promote self-interaction, using the DNA binding domain of
repressor as a
reporter. Furthermore, two genetically engineered in-frame deletion
mutations that removed D2 from invasinpstb were significantly less proficient than wild-type
invasinpstb at promoting uptake, although the
amount of surface-exposed invasin as well as the cell binding capacity
of the recombinant Escherichia coli strains remained
similar. Competitive uptake assays showed that E. coli
cells expressing invasinpstb had a significant advantage in the internalization process versus either E. coli cells expressing invasinent or the
invasinpstb derivatives deleted for D2, further
demonstrating the importance of invasin self-interaction for the
efficiency of invasin-mediated uptake.
*
Corresponding author. Mailing address: Department of
Molecular Biology & Microbiology, Tufts University School of Medicine, Howard Hughes Medical Institute, 136 Harrison Ave., Boston, MA 02111. Phone: (617) 636-3993. Fax: (617) 636-0337. E-mail:
risberg{at}opal.tufts.edu.
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