Metabolic control analysis reveals an important role for diacylglycerol acyltransferase in olive but not in oil palm lipid accumulation

Abstract

We applied metabolic control analysis to the Kennedy pathway for triacylglycerol formation in tissue cultures from the important oil crops, olive (Olea europaea L.) and oil palm (Elaeis guineensis Jacq.). When microsomal fractions were incubated at 30 °C rather than 20 °C, there was an increase in triacylglycerol labelling. This increase was accompanied by a build up of diacylglycerol (DAG) radioactivity in olive but not in oil palm, suggesting that the activity of DAG acyltransferase (DAGAT) was becoming limiting in olive. We used 2‐bromooctanoate as a specific inhibitor of DAGAT and showed that the enzyme had a flux control coefficient under the experimental conditions of 0.74 in olive but only 0.12 in oil palm. These data revealed important differences in the regulation of lipid biosynthesis in cultures from different plants and suggest that changes in the endogenous activity of DAGAT is unlikely to affect oil accumulation in oil palm crops.

Metabolic flux analysis in plants using dynamic labeling technique: Application to tryptophan biosynthesis in cultured rice cells

“…The flux control-coefficient values obtained by the metabolic control analysis (MCA) indicate the quantitative expression of a so-called ''rate-controlling step'' in the metabolic pathway (Kacser and Burns, 1973;Fell, 1997). Although several pioneer MCA works have dealt with plant metabolic pathways Ramli et al, 2005;Thomas et al, 1997), the importance of estimating the flux control-coefficients in the study of plant metabolism should be more considered in order to provide fundamental information for the rational manipulation of metabolic pathways (Nielsen, 1998). Advances in data analysis techniques based on computer simulation will facilitate the MCA as well as MFA of more complex metabolic networks using the dynamic labeling method, which will for sure unveil the regulatory mechanisms of metabolic pathways in plants.…”

Malic enzyme: the controlling activity for lipid production? Overexpression of malic enzyme in Mucor circinelloides leads to a 2.5-fold increase in lipid accumulation

“…Whilst various proposals have been made to determine the rate-limiting step in both micro-organisms and plants (Ratledge & Wynn, 2002;Ohlrogge & Jaworski, 1997;Ramli et al, 2005), none of the possible enzymes involved in either acetyl-CoA generation or fatty acid synthesis appears to have been vindicated by subsequent cloning experiments (Ohlrogge & Jaworski, 1997;Rangasamy & Ratledge, 2000). In our detailed biochemical analysis of lipid accumulation in Mc.…”

“…Various attempts have been made with plants to increase the flux of carbon into fatty acid biosynthesis and to identify possible bottlenecks, with subsequent genetic modification being carried out to remove postulated impediments to lipid accumulation. None of these attempts has been successful, with only relatively small increases (~10-15 %) in lipid accumulation being recorded (see for example Broun et al, 1999;Thelen & Ohlrogge, 2002;Rangasamy & Ratledge, 2000;Ramli et al, 2005) following genetic manipulation.…”

Inspiré par les lipides (Médaille Chevreul 2014)

“…La théorie qui se cache derrière ces deux (Fell, 1997). En appliquant l'analyse de contrôle métabolique à plusieurs cultures agricoles clé -huile de palme (Ramli et al, 2002(Ramli et al, , 2009, soja (Guschina et al, 2014), olive (Ramli et al, 2002(Ramli et al, , 2005, colza (Weselake et al, 2008 ;Tang et al, 2012 (Perry et Harwood, 1993 ;Perry et al, 1999). Donc, nous avons augmenté l'expression de DGAT 1 dans des lignées transgéniques et avons montré comment ceci a modifié l'équilibre du contrôle entre les deux blocs de réactions (Weselake et al, 2008).…”