Fungi terpenoid pathway

Benzoquinone carbon atoms can be derived from acetic acid (acetyl-CoA in polyketide quinones) or from glucose (via shikimic acid in microorganisms and fungi). Terpenoid side chains are biosynthesised in the mevalonate (terpenoid) pathway. 

Whilst these biosynthetically-patterned biotransformations of terpenoids have been described in the context of studies with G. fujikuroi, studies with other fungi have shown that a similar pattern of results can be obtained using other biosyntheses. Although the yields of the metabolites are often poor, the transformations do have some value in the preparation of rare or labelled compounds. Furthermore, the results reveal some constraints on the biosynthetic pathways and provide information on the stereo-electronic requirements of enzymatic processes that could not be obtained from conventional studies. 

Carotenoids of higher plants, algae, and fungi are C40 tetraterpenes biosynthesized by the well-known isoprenoid pathway [1, 5, 6, 8, 17, 18]. The early steps, involving the formation of the C5 isoprenoid units and the subsequent synthesis of prenyldiphosphate intermediates, are common to all classes of terpenoids. 

The importance of terpenoids to life is highlighted by the fact that two separate pathways have been found to produce the terpenoid precursor C5 units isopentenyl diphosphate (IDP) and dimethylaUyl diphosphate (DMADP). The mevalonic acid (MVA) pathway is functional in archae, animals and fungi, 2-C-methyl-D-erythritol-4-phosphate (MEP) pathway is found in green algae, and terpenoids are produced by both pathways in bacteria and plants [2]. In plants the MVA pathway is active in the cytosol and it provides C5 units for sesquiterpene, triterpene and polyterpene biosynthesis whereas the MEP pathway occurs in plastids and produces C5 units for isoprene, monoterpenes, diterpenes and carotenoids [1]. Recent reports have indicated metabolic crosstalk between biosynthesis pathways and e.g., the homoterpene DMNT may originate from both pathways. 

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