LaoABCR, a Novel System for Oxidation of Long-Chain Alcohols Derived from SDS and Alkane Degradation in Pseudomonas aeruginosa

Abstract

The opportunistic pathogen strain PAO1 is able to use a variety of organic pollutants as growth substrates, including the anionic detergent sodium dodecyl sulfate (SDS) and long-chain alkanes. While the enzymes initiating SDS and alkane degradation are well known, the subsequent enzymatic steps for degradation of the derived primary long-chain alcohols have not yet been identified. By evaluating genes specifically induced during growth with SDS, a gene cluster encoding a putative alcohol dehydrogenase (PA0364/LaoA), a probable inner membrane protein (PA0365/LaoB), and a presumable aldehyde dehydrogenase (PA0366/LaoC) was identified and designated the Lao (ong-chain-lcohol/ldehyde-xidation) system. Growth experiments with deletion mutants with SDS, 1-dodecanol, and alkanes revealed that LaoA and LaoB are involved in the degradation of primary long-chain alcohols. Moreover, detection of 1-dodecanol oxidation in cell extracts by activity staining revealed an interdependency of LaoA and LaoB for efficient 1-dodecanol oxidation. An analysis yielded no well-characterized homologue proteins for LaoA and LaoB. Furthermore, a gene adjacent to the gene cluster encodes a putative transcriptional regulator (PA0367/LaoR). A deletion mutant exhibited constitutive expression of LaoA and LaoB, indicating that LaoR is a repressor for the expression of Taken together, these results showed that the proteins LaoA and LaoB constitute a novel oxidation system for long-chain alcohols derived from pollutants. The versatile and highly adaptive bacterium a is able to colonize a variety of habitats, including anthropogenic environments, where it is often challenged with toxic compounds. Its ability to degrade such compounds and to use them as growth substrates can significantly enhance spreading of this opportunistic pathogen in hygienic settings, such as clinics or water distribution systems. Thus, knowledge about the metabolism of can contribute to novel approaches for preventing its growth and reducing nosocomial infections. As the Lao system is important for the degradation of two different classes of pollutants, the identification of these novel enzymes can be a useful contribution for developing effective antibacterial strategies.

Genomic and Functional Characterization of Environmental Strains of SDS-Degrading Pseudomonas spp., Providing a Source of New Sulfatases

“…Although the research was focused mainly on the stress response also some genes involved in the degradation of SDS were proposed, including the sdsA1 (coding alkylsulfatase) or putative dehydrogenases (PA0364 and PA0366) possibly responsible for further oxidation steps after the hydrolysis of SDS to dodecanol ( Klebensberger et al, 2009 ). These suggestions were recently confirmed by mutants analysis and resulted in identification of laoABC gene cluster coding long-chain alcohols oxidation system ( Panasia and Philipp, 2018 ).…”

“…This year a first attempt to identify the enzymes involved in the further SDS metabolic pathway in P. aeruginosa PAO1 was performed. The results from microarray analysis, verified by the characterization of appropriate deletion mutants, led to identification laoABC gene cluster coding long-chain alcohols oxidation system responsible for the dodecanol and dodecanal oxidation ( Panasia and Philipp, 2018 ).…”

Protein expression in the obligate hydrocarbon‐degrading psychrophile Oleispira antarctica RB‐8 during alkane degradation and cold tolerance

“…LaoA from P . aeruginosa is part of a gene cluster that was shown to oxidize the alcohols derived from the alkane degradation and also contains an inner membrane transport protein (LaoB/PA0365), an aldehyde dehydrogenase (LaoC/PA0366) and a transcriptional regulator (LaoR/PA0367) (Panasia and Philipp, ). This genetic organization is also seen in O .…”

Pseudomonas syringaedual‐function protein Lon switches between virulence and metabolism by acting as bothDNA‐binding transcriptional regulator and protease in different environments

“…LaoR (PSPPH_4788 orthologue) is a repressor of the laoABC operon (orthologues of PSPPH_0505, PSPPH_1629 and PSPPH_2732), which is responsible for oxidizing longchain alcohols in P. aeruginosa (Panasia and Philipp, 2018). To further investigate the function of PSPPH_4788, we used RT-qPCR to determine the expression levels of its downstream genes.…”

“…The procedure from a previous study was followed (Panasia and Philipp, 2018). Briefly, the assay was performed in a 1 ml volume with cell extract (100 μg protein), 1 mM NAD + , 150 μM PMS and 200 μM NBT and filled up with the reaction buffer (Tris-HCl [pH 8.8] with 10 mM 1-dodecanol) at 28 C for 5 min.…”