Background: Three T6SSs are present in P. aeruginosa. H1-T6SS secretes bacteriolytic toxins.Results: H2-T6SS is regulated by quorum sensing and Fur and modulates internalization in epithelial cells through PI3K-Akt host pathway activation.Conclusion: H2-T6SS plays a role in virulence.Significance: In contrast to the anti-prokaryotic H1-T6SS, H2-T6SS targets human cells. Those T6SSs can carry out different functions important in establishing infection.

Although preB cell-receptor (pre-BCR) formation and cell-surface expression is essential for B cell development, pre-BCR generation of signal transduction remains elusive. Here, we report that recombinant pre-BCRs and the surrogate light chain bind specifically to the bone marrow stromal cell galectin-1 (GAL1), an S-type lectin. The surrogate light chain͞GAL1 association is a direct protein-protein interaction (K a ‫؍‬ 2 ؋ 10 6 M ؊1 ), and the NH2 extra loop of -like is the major binding element. Pre-BCR binding to stromal cells depends upon GAL1 anchoring to glycosylated counter-receptors, and these complexes completely relocalize to form a synapse at the contact zone between preB and stromal cells. This immune developmental synapse is accompanied by the initiation of intracellular tyrosine kinase activity and signal transduction from the pre-BCR.