| Title: | Functional Characterization of a 28-Kilobase Catabolic Island from Pseudomonas sp. Strain M1 Involved in Biotransformation of beta-Myrcene and Related Plant-Derived Volatiles |
| Author(s): | Soares-Castro P; Montenegro-Silva P; Heipieper HJ; Santos PM; |
| Address: | "CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Braga, Portugal. Helmholtz Centre for Environmental Research-UFZ, Department of Environmental Biotechnology, Leipzig, Germany. CBMA-Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Braga, Portugal psantos@bio.uminho.pt" |
| ISSN/ISBN: | 1098-5336 (Electronic) 0099-2240 (Print) 0099-2240 (Linking) |
| Abstract: | "Pseudomonas sp. strain M1 is able to mineralize highly hydrophobic and recalcitrant compounds, such as benzene, phenol, and their methylated/halogenated derivatives, as well as the backbone of several monoterpenes. The ability to use such a spectrum of compounds as the sole carbon source is, most probably, associated with a genetic background evolved under different environmental constraints. The outstanding performance of strain M1 regarding beta-myrcene catabolism was elucidated in this work, with a focus on the biocatalytical potential of the beta-myrcene-associated core code, comprised in a 28-kb genomic island (GI), predicted to be organized in 8 transcriptional units. Functional characterization of this locus with promoter probes and analytical approaches validated the genetic organization predicted in silico and associated the beta-myrcene-induced promoter activity to the production of beta-myrcene derivatives. Notably, by using a whole-genome mutagenesis strategy, different genotypes of the 28-kb GI were generated, resulting in the identification of a novel putative beta-myrcene hydroxylase, responsible for the initial oxidation of beta-myrcene into myrcen-8-ol, and a sensor-like regulatory protein, whose inactivation abolished the myr(+) trait of M1 cells. Moreover, it was demonstrated that the range of monoterpene substrates of the M1 enzymatic repertoire, besides beta-myrcene, also includes other acyclic (e.g., beta-linalool) and cyclic [e.g., R-(+)-limonene and (-)-beta-pinene] molecules. Our findings are the cornerstone for following metabolic engineering approaches and hint at a major role of the 28-kb GI in the biotransformation of a broad monoterpene backbone spectrum for its future biotechnological applications.IMPORTANCE Information regarding microbial systems able to biotransform monoterpenes, especially beta-myrcene, is limited and focused mainly on nonsystematic metabolite identification. Complete and detailed knowledge at the genetic, protein, metabolite, and regulatory levels is essential in order to set a model organism or a catabolic system as a biotechnology tool. Moreover, molecular characterization of reported systems is scarce, almost nonexistent, limiting advances in the development of optimized cell factories with strategies based on the new generation of metabolic engineering platforms. This study provides new insights into the intricate molecular functionalities associated with beta-myrcene catabolism in Pseudomonas, envisaging the production of a molecular knowledge base about the underlying catalytic and regulatory mechanisms of plant-derived volatile catabolic pathways" |
| Keywords: | "Acyclic Monoterpenes Biotransformation Computational Biology DNA Mutational Analysis Gene Expression Profiling Gene Order *Genes, Bacterial *Genomic Islands Genotype Metabolic Networks and Pathways/*genetics Monoterpenes/*metabolism Phytochemicals/metabol;" |
| Notes: | "MedlineSoares-Castro, Pedro Montenegro-Silva, Pedro Heipieper, Hermann J Santos, Pedro M eng 2017/02/19 Appl Environ Microbiol. 2017 Apr 17; 83(9):e03112-16. doi: 10.1128/AEM.03112-16. Print 2017 May 1" |
