Quinolone Signal molecule PQS behaves like a B Class inhibitor at the I site of mitochondrial complex I.

is a Gram-negative bacterium of the proteobacteria class, and one of the most common causes of nosocomial infections. For example, it causes chronic pneumonia in cystic fibrosis patients. Patient sputum contains 2-heptyl-4-hydroxyquinoline -oxide [HQNO] and quorum sensing molecules such as the quinolone signal [PQS].