A PQS-Cleaving Quorum Quenching Enzyme Targets Extracellular Membrane Vesicles of .

The opportunistic pathogen uses quorum sensing to control its virulence. One of its major signal molecules, the quinolone signal PQS, has high affinity to membranes and is known to be trafficked mainly via outer membrane vesicles (OMVs). We previously reported that several 3-hydroxy-4(1)-quinolone 2,4-dioxygenases (HQDs) catalyze the cleavage of PQS and thus act as quorum quenching enzymes.

Azetidomonamide and Diazetidomonapyridone Metabolites Control Biofilm Formation and Pigment Synthesis in .

Synthesis of azetidine-derived natural products by the opportunistic pathogen is controlled by quorum sensing, a process involving the production and sensing of diffusible signal molecules that is decisive for virulence regulation. In this study, we engineered for the titratable expression of the biosynthetic gene cluster, which allowed the purification and identification of two new products, azetidomonamide C and diazetidomonapyridone. Diazetidomonapyridone was shown to have a highly unusual structure with two azetidine rings and an open-chain diimide moiety.

A comparative study of N-hydroxylating flavoprotein monooxygenases reveals differences in kinetics and cofactor binding.

Many natural products comprise N-O containing functional groups with crucial roles for biological activity. Their enzymatic formation is predominantly achieved by oxidation of an amine to form a hydroxylamine, which enables further functionalization. N-hydroxylation by flavin-dependent enzymes has so far been attributed to a distinct group of flavoprotein monooxygenases (FPMOs) containing two dinucleotide binding domains.

Enzyme-Mediated Quenching of the Quinolone Signal (PQS): A Comparison between Naturally Occurring and Engineered PQS-Cleaving Dioxygenases.

The opportunistic pathogen employs quorum sensing to govern the production of many virulence factors. Interference with quorum sensing signaling has therefore been put forward as an attractive approach to disarm this pathogen. Here, we analyzed the quorum quenching properties of natural and engineered (2-alkyl-)3-hydroxy-4(1)-quinolone 2,4-dioxygenases (HQDs) that inactivate the signal molecule PQS ( quinolone signal; 2-heptyl-3-hydroxy-4(1)-quinolone).

Structural basis of O-methylation of (2-heptyl-)1-hydroxyquinolin-4(1H)-one and related compounds by the heterocyclic toxin methyltransferase Rv0560c of Mycobacterium tuberculosis.

The S-adenosyl-L-methionine-dependent methyltransferase Rv0560c of Mycobacterium tuberculosis belongs to an orthologous group of heterocyclic toxin methyltransferases (Htm) which likely contribute to resistance of mycobacteria towards antimicrobial natural compounds as well as drugs. Htm catalyzes the methylation of the Pseudomonas aeruginosa toxin 2-heptyl-1-hydroxyquinolin-4(1H)-one (also known as 2-heptyl-4-hydroxyquinoline N-oxide), a potent inhibitor of respiratory electron transfer, its 1-hydroxyquinolin-4(1H)-one core (QNO), structurally related (iso)quinolones, and some mycobactericidal compounds. In this study, crystal structures of Htm in complex with S-adenosyl-L-homocysteine (SAH) and the methyl-accepting substrates QNO or 4-hydroxyisoquinoline-1(2H)-one, or the methylated product 1-methoxyquinolin-4(1H)-one, were determined at < 1.