Pyrimidine Biosynthesis Regulates the Small-Colony Variant and Mucoidy in Pseudomonas aeruginosa through Sigma Factor Competition

Chronic lung infections with P. aeruginosa are the main cause of morbidity and mortality in patients with cystic fibrosis. This bacterium overproduces a capsular polysaccharide called alginate (also known as mucoidy), which aids in bacterial persistence in the lungs and in resistance to therapeutic regimens and host immune responses. The current study explores a previously unknown link between pyrimidine biosynthesis and mucoidy at the level of transcriptional regulation. Identifying/characterizing this link could provide novel targets for the control of bacterial growth and mucoidy. Inhibiting mucoidy may improve antimicrobial efficacy and facilitate host defenses to clear the noncapsulated P. aeruginosa bacteria, leading to improved prognosis for patients with cystic fibrosis.