Adaptation to beta-myrcene catabolism in Pseudomonas sp. M1: an expression proteomics analysis

Beta-myrcene, a monoterpene widely used as a fragrance and flavoring additive, also possesses analgesic, anti-mutagenic, and tyrosinase inhibitory properties. In order to get insights into the molecular mechanisms underlying the ability of Pseudomonas sp. M1 to catabolize beta-myrcene, an expression proteomics approach was used in this study. Results indicate that the catabolic enzyme machinery for beta-myrcene utilization (MyrB, MyrC, and MyrD and other uncharacterized proteins) is strongly induced when beta-myrcene is present in the growth medium. Since an M1 mutant, lacking a functional 2-methylisocitrate dehydratase, is not able to grow in mineral medium with beta-myrcene or propionic acid as the sole C-source, and also based on the expression proteomic analysis carried out in this study, it is suggested that the beta-myrcene catabolic intermediate propionyl-CoA is channeled into the central metabolism via the 2-methylcitrate cycle. Results also suggest that the major alteration occurring in the central carbon metabolism of cells growing in beta-myrcene-containing media is related with the redistribution of the metabolic fluxes leading to increased oxaloacetate production. Other up-regulated proteins are believed to prevent protein misfolding and aggregation or to play important structural roles, contributing to the adaptive alteration of cell wall and membrane organization and integrity, which are essential features to allow the bacterium to cope with the highly lipophilic beta-myrcene as C-source.