Role of the beta1-integrin cytoplasmic tail in mediating invasin-promoted internalization of Yersinia.
Invasin of Yersinia pseudotuberculosis binds to beta1-integrins on host cells and triggers internalization of the bacterium. To elucidate the mechanism behind the beta1-integrin-mediated internalization of Yersinia, a beta1-integrin-deficient cell line, GD25, transfected with wild-type beta1A, beta1B or different mutants of the beta1A subunit was used. Both beta1A and beta1B bound to invasin-expressing bacteria, but only beta1A was able to mediate internalization of the bacteria. The cytoplasmic region of beta1A, differing from beta1B, contains two NPXY motifs surrounding a double threonine site. Exchanging the tyrosines of the two NPXYs to phenylalanines did not inhibit the uptake, whereas a marked reduction was seen when the first tyrosine (Y783) was exchanged to alanine. A similar reduction was seen when the two nearby threonines (TT788-9) were exchanged with alanines. It was also noted that cells affected in bacterial internalization exhibited reduced spreading capability when seeded onto invasin, suggesting a correlation between the internalization of invasin-expressing bacteria and invasin-induced spreading. Likewise, integrins defective in forming peripheral focal complex structures was unable to mediate uptake of invasin-expressing bacteria.
Gustavsson
Anna
A
Department of Microbiology, Umeå University, 901 87 Umeå, Sweden.
Armulik
Annika
A
Brakebusch
Cord
C
Fässler
Reinhard
R
Johansson
Staffan
S
Fällman
Maria
M
D018829:Adhesins, Bacterial / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000502:physiology; D002448:Cell Adhesion / Q000235:genetics; D002450:Cell Communication / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010587:Phagocytosis / Q000502:physiology*; D011485:Protein Binding / Q000502:physiology; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019096:Vitronectin; D015011:Yersinia pseudotuberculosis / Q000166:cytology / Q000378:metabolism* / Q000472:pathogenicity; D015012:Yersinia pseudotuberculosis Infections / Q000378:metabolism* / Q000503:physiopathology
D018829:Adhesins, Bacterial; D004791:Enzyme Inhibitors; D019012:Integrin beta1; D020033:Protein Isoforms; D019096:Vitronectin; C053476:invasin, Yersinia; D014443:Tyrosine