Metabolic diversification

Pyruvate (7.5 equiv) CTP (1.5 equiv) NeuA, CSS CstllA32(l53S) 

---

Field B, Osbourn AE (2008) Metabolic diversification - Independent assembly of operon-like gene clusters in different plants. Science 320 543-547... 

TakemuraT, IkezavaN, Iwasa K, Sato F. Metabolic diversification of Benzylisoqui-none alkaloid biosynthesis through the introduction of a branch pathway in EschschoMa cahfomica. Plant Cell Physiol 2010 51(6) 949-59. 

The production of tens of thousands of natural products or secondary metabolites (SMs) by plants is a consequence of metabolic diversification coupled with selection. Numerous roles of these substances in the plant life cycle have now been described. These include diverse functions associated with both the interaction of the plant with the environment (both biotic and abiotic aspects) and the assurance of successful reproduction. The importance of these molecules to the plant often receives relatively little attention in comparison with the focus on the... 

St-Pierre, B. and De Luca, V., Evolution of acyltransferase genes origin and diversification of the BAHD superfamily of acyltransferases involved in secondary metabolism, in Evolution of Meta-... 

In order to understand fully the importance of these chemical factors, it is necessary to consider the processes which are probably responsible for their diversification. A mechanism of coevolution of insects and plants was set forth eloquently by Erlich and Raven (4). According to their hypothesis, angiosperms produced a series of chemical compounds which were not directly related to their basic (or primary) metabolic pathways, but which were otherwise not harmful to the plants growth and development. 

The establishment of plant integrated defenses involves the preferential evolutionary retention and production of those SCs exerting synergistic toxic effects and is possible only if a diversification of secondary metabolism in a given plant has previously occurred. This preliminary diversification of secondary metabolism could be mediated via the classical reciprocal co-evolutionary interactions between a host plant and its major pests, as predicted by the chemical arms race model (Beren-baum and Zangerl, 1996). The PICD hypothesis is consequently not an exclusive evolutionary hypothesis because it is compatible with and dependent on other evolutionary processes. The contribution of the PICD hypothesis is to provide both a functional explanation for the diversity of SCs within plants (Romeo et al, 1996) and a reconciliation between different evolutionary models. 

ST. PIERRE, B., DE LUCA, V., Evolution of acyltransferase genes Origin and diversification of the BAHD suprfamily of acyltransferases involved in secondary metabolism, in Evolution of Metabolic Pathways Rec. Adv. Phytochemistry Vol. 34 (J.T. Romeo, R.K. Ibrahim, L. Varin, V. De Luca, eds.), Pergamon Press, Amsterdam. 2000, pp.285-315. 

KLIEBENSTEIN, D.J., LAMBR1X, V.M., REICHELT, M., GERSHENZON, J., MITCHELL-OLDS, T., Gene duplication in the diversification of secondary metabolism Tandem 2-oxoglutarate-dependent dioxygenases control glucosinolate biosynthesis in Arabidopsis., Plant Cell, 2001,13,681-693. 

Ober, D. (2005) Seeing double- gene duplication and diversification in plant secondary metabolism. Trends Plant Sci., 10,444—9. 

The wide distribution of PKSs in the microbial world and the extreme chemical diversity of their products do in fact result from a varied use of the well-known catalytic domains described above for the canonical PKS systems. Taking a theoretic view of polyketide diversity, Gonzalez-Lergier et al. (41) have suggested that even if the starter and extender units are fixed, over 100,000 linear heptaketide structures are possible using only the 5 common reductive outcomes at the P-carbon position (ketone, (R- or S-) alcohol, trans-double bond, or alkane). Recently, it has become apparent that even this does not represent the upper limit for polyketide diversification. To create chemical functionalities beyond those mentioned above, nature has recruited some enzymes from sources other than fatty acid synthesis (the mevalonate pathway in primary metabolism is one example) not typically thought of as type I PKS domains. Next, we explore the ways PKS-containing systems have modified these domains for the catalysis of some unique chemistries observed in natural products. 

Development is composed of two phenomena, growth and differentiation. The latter is the progressive diversification of structure and function of cells in an organism or the acquisition of differences during development [47]. Differentiation encompasses both morphological differentiation (morphogenesis) and chemical differentiation (secondary metabolism). Secondary metabolites produced by chemical differentiation processes also function in morphological and chemical differentiation. 

Kubitzki, K. (1987). Phenylpropanoid metabolism in relation to land plant origin and diversification./. Planl. Physiol. 131, 17-24. 

Insects generally are able to synthesize alkaloids themselves or take them from feed. Alkaloids play an important role in insect metabolism, behavior, protection mechanisms, and species diversification. Many pyrrolizidine alkaloid-adapted insects convert host plant pyrrolizidine alkaloids into insect pyrrolizidine alkaloids. In this operation, the acid component of plant alkaloid is replaced by 2-hydroxy acids of insect origin. This seems to be an effect of physiological adaptation and evolutionary changes in the muton. Insect pyrrolizidine alkaloids can be precursors of insect pheromone hydroxydanaidal in many species. 

---