Cell-surface signalling systems are widespread in Gram-negative bacteria. In these systems gene expression occurs following binding of a ligand, commonly a siderophore, to a receptor protein in the outer membrane. The receptor interacts with a sigma regulator protein that extends from the periplasm into the cytoplasm to control the activity of a cognate sigma factor. The mechanisms of signal transduction in cell-surface signalling systems have not been determined. Here we investigate signal transduction in the @entity28907 , @entity32556 and @entity5532 siderophore systems of @entity796 . When @entity28907 is present the sigma regulator FpvR undergoes complete proteolysis resulting in activation of two sigma factors PvdS and FpvI and expression of genes for @entity28907 synthesis and uptake. When @entity28907 is absent subfragments of FpvR inhibit PvdS and FpvI. Similarly, subfragments of the sigma regulators FoxR and FiuR are formed in the absence of @entity5532 and @entity32556 . These are much less abundant when the siderophores are present and downstream gene expression takes place. In all three systems RseP (MucP/YaeL) is required for complete proteolysis of the sigma regulator and sigma factor activity. These findings indicate that regulated proteolysis is a general mechanism for signal transduction in cell-surface signalling.

Differential proteolysis of sigma regulators controls cell-surface signalling in XXXX .

@entity796 :: ('287', 'Species') :: ['Pseudomonas aeruginosa'] @entity28907 :: ('MESH:C042453', 'Chemical') :: ['pyoverdine'] @entity5532 :: ('MESH:D003676', 'Chemical') :: ['desferrioxamine'] @entity32556 :: ('MESH:D005291', 'Chemical') :: ['ferrichrome']
@entity796 :: (287,Species) :: ['Pseudomonas aeruginosa']
