Bacterial metabolism of 2-methylquinoline and naturally occurring 2-alkyl-4(1H) quinolones: (I) Transcriptional regulation of 2-methylquinoline degradation, (II) Bacterial strains and enzymes for the inactivation of 2-alkyl-4(1H)quinolones

• Applicant: Professorin Dr. Susanne Fetzner
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2009 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 94596318

2-Methylquinoline degradation by Arthrobacter nitroguajacolicus Rü61a to anthranilate is encoded by two “upper pathway” operons located on the linear plasmid pAL1. Anthranilate can be degraded via a chromosomal catechol pathway, however, another operon of pAL1 was proposed to encode “lower pathway” enzymes for anthranilate conversion via coenzyme A intermediates. Two PaaX-type regulators are involved in transcriptional control of the catabolic operons of pAL1, which in view of the current notion that PaaX proteins are restricted to the phenylacetate catabolon is an unexpected finding. The first part of the project aims at characterizing the transcriptional regulation of catabolic operons of pAL1. The following topics will be addressed: (i) Activities of catabolic promoters and of promoters of the paaX-like genes in response to carbon compounds; (ii) role of PaaX-like proteins in regulation of catabolic operons, and possible auto-regulation/reciprocal regulation of paaX genes by their gene products; (iii) identification of PaaX-responsive operator sequences, and effector specificity of the PaaX proteins; (iv) identification of other promoter-binding proteins; (v) characterization of pAL1-encoded genes for anthranilate conversion. The second section of the project addresses the question how bacteria degrade naturally occurring alkylquinolones, such as 2-heptyl-4(1H)quinolone and 2-heptyl-3-hydroxy-4(1H)quinolone, which are important quorum sensing signalling molecules of Pseudomonas aeruginosa. The goal is to identify novel enzymes for the inactivation of these compounds.

• DFG Programme: Research Grants