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.

A Complex of LaoA and LaoB Acts as a Tat-Dependent Dehydrogenase for Long-Chain Alcohols in Pseudomonas aeruginosa.

The opportunistic pathogen Pseudomonas aeruginosa can utilize unusual carbon sources, like sodium dodecyl sulfate (SDS) and alkanes. Whereas the initiating enzymatic steps of the corresponding degradation pathways have been characterized in detail, the oxidation of the emerging long-chain alcohols has received little attention. Recently, the genes for the Lao (ong-chain-lcohol/ldehyde xidation) system were discovered to be involved in the oxidation of long-chain alcohols derived from SDS and alkane degradation.

Substrate Inhibition of 5β-Δ-3-Ketosteroid Dehydrogenase in sp. Strain Chol11 Acts as Circuit Breaker During Growth With Toxic Bile Salts.

In contrast to many steroid hormones and cholesterol, mammalian bile salts are 5β-steroids, which leads to a bent structure of the steroid core. Bile salts are surface-active steroids excreted into the environment in large amounts, where they are subject to bacterial degradation. Bacterial steroid degradation is initiated by the oxidation of the A-ring leading to canonical Δ-3-keto steroids with a double bond in the A-ring.

Signal Synthase-Type versus Catabolic Monooxygenases: Retracing 3-Hydroxylation of 2-Alkylquinolones and Their -Oxides by Pseudomonas aeruginosa and Other Pulmonary Pathogens.

The multiple biological activities of 2-alkylquinolones (AQs) are crucial for virulence of , conferring advantages during infection and in polymicrobial communities. Whereas 2-heptyl-3-hydroxyquinolin-4(1)-one (the " quinolone signal" [PQS]) is an important quorum sensing signal molecule, 2-alkyl-1-hydroxyquinolin-4(1)-ones (also known as 2-alkyl-4-hydroxyquinoline -oxides [AQNOs]) are antibiotics inhibiting respiration. Hydroxylation of the PQS precursor 2-heptylquinolin-4(1)-one (HHQ) by the signal synthase PqsH boosts AQ quorum sensing.

Photoinduced monooxygenation involving NAD(P)H-FAD sequential single-electron transfer.

Light-dependent or light-stimulated catalysis provides a multitude of perspectives for implementation in technological or biomedical applications. Despite substantial progress made in the field of photobiocatalysis, the number of usable light-responsive enzymes is still very limited. Flavoproteins have exceptional potential for photocatalytic applications because the name-giving cofactor intrinsically features light-dependent reactivity, undergoing photoreduction with a variety of organic electron donors.

Interference with Pseudomonas aeruginosa Quorum Sensing and Virulence by the Mycobacterial Quinolone Signal Dioxygenase AqdC in Combination with the -Acylhomoserine Lactone Lactonase QsdA.

The nosocomial pathogen regulates its virulence via a complex quorum sensing network, which, besides -acylhomoserine lactones, includes the alkylquinolone signal molecules 2-heptyl-3-hydroxy-4(1)-quinolone ( quinolone signal [PQS]) and 2-heptyl-4(1)-quinolone (HHQ). subsp. , an emerging pathogen, is capable of degrading the PQS and also HHQ.

Bromination of alkyl quinolones by Microbulbifer sp. HZ11, a marine Gammaproteobacterium, modulates their antibacterial activity.

Alkyl quinolones (AQs) are multifunctional bacterial secondary metabolites generally known for their antibacterial and algicidal properties. Certain representatives are also employed as signalling molecules of Burkholderia strains and Pseudomonas aeruginosa. The marine Gammaproteobacterium Microbulbifer sp.

PqsL uses reduced flavin to produce 2-hydroxylaminobenzoylacetate, a preferred PqsBC substrate in alkyl quinolone biosynthesis in .

Alkyl hydroxyquinoline -oxides (AQNOs) are antibiotic compounds produced by the opportunistic bacterial pathogen They are products of the alkyl quinolone (AQ) biosynthetic pathway, which also generates the quorum-sensing molecules 2-heptyl-4(1)-quinolone (HHQ) and 2-heptyl-3-hydroxy-4(1)-quinolone (PQS). Although the enzymatic synthesis of HHQ and PQS had been elucidated, the route by which AQNOs are synthesized remained elusive. Here, we report on PqsL, the key enzyme for AQNO production, which structurally resembles class A flavoprotein monooxygenases such as -hydroxybenzoate 3-hydroxylase (pHBH) and 3-hydroxybenzoate 6-hydroxylase.

One gene, two proteins: coordinated production of a copper chaperone by differential transcript formation and translational frameshifting in Escherichia coli.

Programmed ribosomal frameshifting (PRF) is a translational anomaly causing the ribosome to shift into an alternative reading frame. PRFs are common in viral genomes, using a single nucleotide sequence to code for two proteins in overlapping frames. In bacteria and eukaryota, PRFs are less frequent.

Polypharmacology Approaches against the Pseudomonas aeruginosa MvfR Regulon and Their Application in Blocking Virulence and Antibiotic Tolerance.

Pseudomonas aeruginosa is an important nosocomial pathogen that is frequently recalcitrant to available antibiotics, underlining the urgent need for alternative therapeutic options against this pathogen. Targeting virulence functions is a promising alternative strategy as it is expected to generate less-selective resistance to treatment compared to antibiotics. Capitalizing on our nonligand-based benzamide-benzimidazole (BB) core structure compounds reported to efficiently block the activity of the P.

An unexplored pathway for degradation of cholate requires a 7α-hydroxysteroid dehydratase and contributes to a broad metabolic repertoire for the utilization of bile salts in Novosphingobium sp. strain Chol11.

Bile salts such as cholate are surface-active steroid compounds with functions for digestion and signaling in vertebrates. Upon excretion into soil and water bile salts are an electron- and carbon-rich growth substrate for environmental bacteria. Degradation of bile salts proceeds via intermediates with a 3-keto-Δ -diene structure of the steroid skeleton as shown for e.

PqsBC, a Condensing Enzyme in the Biosynthesis of the Pseudomonas aeruginosa Quinolone Signal: CRYSTAL STRUCTURE, INHIBITION, AND REACTION MECHANISM.

Pseudomonas aeruginosaproduces a number of alkylquinolone-type secondary metabolites best known for their antimicrobial effects and involvement in cell-cell communication. In the alkylquinolone biosynthetic pathway, the β-ketoacyl-(acyl carrier protein) synthase III (FabH)-like enzyme PqsBC catalyzes the condensation of octanoyl-coenzyme A and 2-aminobenzoylacetate (2-ABA) to form the signal molecule 2-heptyl-4(1H)-quinolone. PqsBC, a potential drug target, is unique for its heterodimeric arrangement and an active site different from that of canonical FabH-like enzymes.

PqsE of Pseudomonas aeruginosa Acts as Pathway-Specific Thioesterase in the Biosynthesis of Alkylquinolone Signaling Molecules.

Pseudomonas aeruginosa uses the alkylquinolones PQS (2-heptyl-3-hydroxy-4(1H)-quinolone) and HHQ (2-heptyl-4(1H)-quinolone) as quorum-sensing signal molecules, controlling the expression of many virulence genes as a function of cell population density. The biosynthesis of HHQ is generally accepted to require the pqsABCD gene products. We now reconstitute the biosynthetic pathway in vitro, and demonstrate that in addition to PqsABCD, PqsE has a role in HHQ synthesis.

Distinct functions of serial metal-binding domains in the Escherichia coli P1 B -ATPase CopA.

P1 B -ATPases are among the most common resistance factors to metal-induced stress. Belonging to the superfamily of P-type ATPases, they are capable of exporting transition metal ions at the expense of adenosine triphosphate (ATP) hydrolysis. P1 B -ATPases share a conserved structure of three cytoplasmic domains linked by a transmembrane domain.

Old molecules, new biochemistry.

The study by Dulcey and colleagues in this issue of Chemistry & Biology changes our perception of the pathway of 2-alkyl-4-hydroxyquinoline biosynthesis by the opportunistic pathogen Pseudomonas aeruginosa and suggests that the biosynthetic protein complex PqsBC is a potential antibacterial target.

FTIR spectroscopy of biofluids revisited: an automated approach to spectral biomarker identification.

The extraction of disease specific information from Fourier transform infrared (FTIR) spectra of human body fluids demands the highest standards of accuracy and reproducibility of measurements because the expected spectral differences between healthy and diseased subjects are very small in relation to a large background absorbance of the whole sample. Here, we demonstrate that with the increased sensitivity of modern FTIR spectrometers, automatisation of sample preparation and modern bioinformatics, it is possible to identify and validate spectral biomarker candidates for distinguishing between urinary bladder cancer (UBC) and inflammation in suspected bladder cancer patients. The current dataset contains spectra of blood serum and plasma samples of 135 patients.

The ATPases CopA and CopB both contribute to copper resistance of the thermoacidophilic archaeon Sulfolobus solfataricus.

Certain heavy metal ions such as copper and zinc serve as essential cofactors of many enzymes, but are toxic at high concentrations. Thus, intracellular levels have to be subtly balanced. P-type ATPases of the P(IB)-subclass play a major role in metal homeostasis.