The Pseudomonas aeruginosa sensor kinase KinB negatively controls alginate production through AlgW-dependent MucA...

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Cystic Fibrosis Research

Background:

• Mucoidy in Pseudomonas aeruginosa, characterized by alginate overproduction, is linked to poor outcomes in cystic fibrosis lung infections.
• While mucA mutations explain some mucoid conversion, wild-type mucA strains also exhibit mucoidy, suggesting alternative regulatory pathways.

Purpose of the Study:

• To investigate the mechanism of mucoid conversion in wild-type Pseudomonas aeruginosa strains lacking mucA mutations.
• To identify novel regulators involved in alginate biosynthesis and mucoidy.

Main Methods:

• Generated a loss-of-function mutation in the kinB gene in the wild-type PAO1 strain.
• Assessed alginate production and expression of alginate-related promoters (P(algU), P(algD)).
• Utilized gene deletions (algB, rpoN) and complementation studies to elucidate regulatory pathways.
• Investigated the role of MucA stability and AlgW protease activity.

Main Results:

• A kinB loss-of-function mutation led to alginate overproduction in wild-type mucA P. aeruginosa.
• This mucoidy was dependent on AlgB and RpoN (sigma54), but not AlgB phosphorylation.
• Inactivation of the AlgW protease in kinB mutants abolished mucoidy and stabilized MucA.
• The kinB mutation accelerated MucA degradation, a process requiring AlgB and RpoN.

Conclusions:

• KinB acts as a negative regulator of alginate production in wild-type P. aeruginosa.
• KinB influences mucoidy by modulating the stability of the anti-sigma factor MucA, likely through the AlgW protease.
• These findings uncover a novel regulatory mechanism for alginate biosynthesis.