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Free keywords:
FIBRONECTIN-BINDING PROTEIN; FOCAL ADHESION KINASE; I
PHOSPHATIDYLINOSITOL-4-PHOSPHATE 5-KINASES; PHOSPHATE KINASE; INTEGRIN
ACTIVATION; BARTONELLA-HENSELAE; STRUCTURAL BASIS; PLASMA-MEMBRANE;
PIPKI-GAMMA; TALINBiochemistry & Molecular Biology; Microbiology; fibronectin-binding protein; internalization; phosphatidylinositol-4;
5-bisphosphate; phosphatidylinositol-4-phosphate-5-kinase;
Staphylococcus aureus;
Abstract:
Staphylococcus aureus, a Gram-positive pathogen, invades cells mainly in an integrin-dependent manner. As the activity or conformation of several integrin-associated proteins can be regulated by phosphatidylinositol-4,5-bisphosphate (PI-4,5-P-2), we investigated the roles of PI-4,5-P-2 and PI-4,5-P-2-producing enzymes in cellular invasion by S. aureus. PI-4,5-P-2 accumulated upon contact of S. aureus with the host cell, and targeting of an active PI-4,5-P-2 phosphatase to the plasma membrane reduced bacterial invasion. Knockdown of individual phosphatidylinositol-4-phosphate 5-kinases revealed that phosphatidylinositol-4-phosphate 5-kinase gamma (PIP5KI gamma) plays an important role in bacterial internalization. Specific ablation of the talin and FAK-binding motif in PIP5KI gamma 90 reduced bacterial invasion, which could be rescued by reexpression of an active, but not inactive PIP5KI gamma 90. Furthermore, PIP5KI gamma 90-deficient cells showed normal basal PI-4,5-P-2 levels in the plasma membrane but reduced the accumulation of PI-4,5-P-2 and talin at sites of S. aureus attachment and overall lower levels of FAK phosphorylation. These results highlight the importance of local synthesis of PI-4,5-P-2 by a focal adhesion-associated lipid kinase for integrin-mediated internalization of S. aureus.
