Images

Figure from Pizarro-Cerda J, Cossart P. Nat Cell Biol. 2004 Nov;6(11):1026-33.

Phophoinositide metabolism flowchart. Main steps in phosphoinositide synthesis and degradation, showing some of the enzymes that catalyze the reactions and the steps subverted by bacterial pathogens. Yersinia species induce activation of a PIP5K to promote PI(4,5)P2 formation; Listeria monocytogenes and UPEC promote the activity of the class I PI3K to generate PI(3,4,5)P3, while EPEC blocks its activity; Mycobacterium tuberculosis, on the other hand, blocks a class III PI3K involved in the formation of PI(3)P; Shigella flexneri translocates into host cells the bacterial enzyme IpgD that dephosphorylates PI(4,5)P2 into PI(5)P; Salmonella enterica also translocates a bacterial effector, SigD/SopB, that presents phosphatidylinositol polyphosphate phosphatase activity and it has been proposed to dephosphorylate the 5’-phosphate from PI(3,5)P2 and PI(3,4,5)P3; SigD/SopB has also been implicated in the turnover of PI(4,5)P2, but the precise PI(4,5)P2 hydrolysis site remains to be determined: it is unknown if SigD/SopB dephosphorylates the 4’-phosphate of PI(4,5)P2 as its homologue IpgD; SigD/SopB presents additionally inositol phosphate phosphatase activity (not shown in the diagram).