Abstract
Plant terpenoids compose a natural source of chemodiversity of exceptional value. Many of these compounds own biological/pharmacological activity, others are regarded as unique chemical skeletons for the synthesis of derivatives with improved properties. Functional chemical modification of terpenoids through biotransformation frequently relies on the use of Ascomycota strains, but information on major cellular responses is still largely lacking. Penicillium janczewskii mediates a stereo-selective hydroxylation of labdanolic acid (LA)—terpenoid found abundantly in Cistus ladanifer—producing 3β-hydroxy-labdanolic acid with yields >90%. Herein, combined analyses of mycelial and extracellular differential proteomes demonstrated that the plant terpenoid increased stress responses, especially against oxidative stress (e.g., accumulation of superoxide dismutase) and apparently altered mitochondria functioning. One putative cytochrome P450 monooxygenase differentially accumulated in the secretome and the terpenoid bioconversion was inhibited in vivo in the presence of a P450 inhibitor. The stereo-selective hydroxylation of the plant terpenoid is likely mediated by P450 enzymes, yet its unequivocal identity remains unclear. To the best of our knowledge, this is the first time that proteomics was used to investigate how a plant terpenoid impacts the metabolism of a filamentous fungus during its efficiently biotransformation. Our findings may encourage the development of new strategies for the valorization of plant natural resources through biotechnology.
Highlights
Terpenoids compose a dissimilar group of natural compounds (>25,000 compounds identified so far) that structurally are saturated and unsaturated cyclic and aliphatic hydrocarbons with variable degrees of oxygenation, including alcohols, aldehydes, ketones, and carboxylic acids (Tholl, 2015)
Similar to our previous study (Frija et al, 2013), we observed that P. janczewskii mediates a stereo-selective hydroxylation of LA yielding predominantly 3β-hydroxy-labdanolic acid (Figure 2) that displays an ion mass (m/z) of 363.2506 [LA] Na+
Comparative proteomic analyses were undertaken to identify in each sub-proteome, the protein spots that increased during growth in the LA medium compared to the control medium
Summary
Terpenoids compose a dissimilar group of natural compounds (>25,000 compounds identified so far) that structurally are saturated and unsaturated cyclic and aliphatic hydrocarbons with variable degrees of oxygenation, including alcohols, aldehydes, ketones, and carboxylic acids (Tholl, 2015). (“Rock-rose”) (Martins et al, 2014a), displays anti-inflammatory properties (Jayaprakasam et al, 2007) and is used as a precursor compound in the chemical synthesis of numerous valuable compounds, e.g., Ambrox® (the prototype compound of all ambergris odorants) (Bolster et al, 2001) This emphasizes well the importance to better understand how this subclass of plant terpenoids impacts on the metabolism of microbes that may be used for their modification. Penicillium janczewskii mediated a stereo-selective hydroxylation of LA yielding 3β-hydroxy-labdanolic acid as the major product (Figure 1) This terpenoid derivative would be, in general, difficult to attain by classical chemical methods and, so far, has never been identified in natural extracts (Frija et al, 2013). This terpenoid derivative would be, in general, difficult to attain by classical chemical methods and, so far, has never been identified in natural extracts (Frija et al, 2013). 3β-Hydroxy-labdanolic acid was used for the chemical synthesis of, e.g., 3β-hydroxy-labd-8(17)-en-15-oic acid— a moderate bactericidal compound, previously identified in the stems of Moldenhawera nutans (Frija et al, 2013)
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