Conversion of the Pseudomonas aeruginosa Quinolone Signal and Related Alkylhydroxyquinolines by Rhodococcus sp. Strain BG43

Abstract

A bacterial strain, which based on the sequences of its 16S rRNA, gyrB, catA, and qsdA genes, was identified as a Rhodococcus sp. closely related to Rhodococcus erythropolis, was isolated from soil by enrichment on the Pseudomonas quinolone signal [PQS; 2-heptyl-3-hydroxy-4(1H)-quinolone], a quorum sensing signal employed by the opportunistic pathogen Pseudomonas aeruginosa. The isolate, termed Rhodococcus sp. strain BG43, cometabolically degraded PQS and its biosynthetic precursor 2-heptyl-4(1H)-quinolone (HHQ) to anthranilic acid. HHQ degradation was accompanied by transient formation of PQS, and HHQ hydroxylation by cell extracts required NADH, indicating that strain BG43 has a HHQ monooxygenase isofunctional to the biosynthetic enzyme PqsH of P. aeruginosa. The enzymes catalyzing HHQ hydroxylation and PQS degradation were inducible by PQS, suggesting a specific pathway. Remarkably, Rhodococcus sp. BG43 is also capable of transforming 2-heptyl-4-hydroxyquinoline-N-oxide to PQS. It thus converts an antibacterial secondary metabolite of P. aeruginosa to a quorum sensing signal molecule.

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

“…Secretion of inhibitory secondary metabolites, among them AQs, is thought to grant fitness advantages during colonization of different habitats, infection of hosts or competition within polymicrobial communities (Long et al ., ; Harvey et al ., ). Not surprisingly, detoxification mechanisms against AQs have evolved during the arms race between the respective metabolite producers and coexisting organisms (Müller et al ., ; Birmes et al ., ; Thierbach et al ., ). In this study, we demonstrate AQs to be brominated at position 3 by the marine bacterium Microbulbifer sp.…”

Rhodococcus erythropolis BG43 Genes Mediating Pseudomonas aeruginosa Quinolone Signal Degradation and Virulence Factor Attenuation

“…Based on in vivo and in vitro biotransformation experiments, we previously proposed a pathway for AQ conversion by R. erythropolis BG43 involving HHQ hydroxylation to PQS by a monooxygenase, followed by cleavage of the heterocyclic ring and alkyl chain removal to form anthranilic acid (37). These reactions were tentatively assumed to proceed analogously to steps of the 2-methylquinoline degradation pathway of Arthrobacter sp.…”

“…Recently, we isolated Rhodococcus erythropolis strain BG43, which is capable of degrading HHQ and PQS to anthranilic acid (37,38). In the present study, we identified two sets of PQS-inducible genes located on a plasmid of strain BG43, which code for the enzymes of the degradation pathway.…”

“…erythropolis BG43 is able to degrade the quorum sensing signal molecules HHQ and PQS from P. aeruginosa (37). Genome se- quence analysis revealed that circular plasmid pRLCBG43 of strain BG43 harbors two sets of genes, aqdA1B1C1 and aqdA2B2C2, possibly coding for enzymes mediating HHQ hydroxylation to PQS and the degradation of PQS to anthranilate.…”

Complete genome sequence of Rhodococcus erythropolis BG43 (DSM 46869), a degrader of Pseudomonas aeruginosa quorum sensing signal molecules

“…Moreover, it is capable of detoxifying the respiratory inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO), which is also produced by P. aeruginosa, by N-oxide reduction and hydroxylation. Like other R. erythropolis strains, strain BG43 contains the qsdA gene coding for an AHL lactonase (Müller et al, 2014). (Angiuoli et al, 2008), resulting in the annotation of 6,158 coding sequences (CDSs).…”