Inhibition of coenzyme Qs accumulation in engineered escherichia coli by high concentration of farnesyl diphosphate

ABSTRACT

Coenzyme Q[10] [CoQ[10]] is an isoprenoid component used widely in nutraceutical industries. Farnesyl diphosphate synthase [FPPS] is a responsible enzyme for biosynthesis of farnesyl diphosphate [FPP], a key precursor for CoQs production. This research involved investigating the effect of FPPS over-expression on CoQs production in engineered CoQ[10]-producing Escherichia coli [E. coli]. Two CoQ[10]-producing strains, as referred to E. coli Ba and E. coli Br, were transformed by the encoding gene for FPPS [ispA] under the control of either the trc or P[BAD] promoters. Over-expression of ispA under the control of P[BAD] promoter led to a relative increase in CoQ[10] production only in recombinant E. coli Br although induction by arabinose resulted in partial reduction of CoQ[10] production in both recombinant E. coli Ba and E. coli Br strains. Over-expression of ispA under the control of stronger trc promoter, however, led to a severe decrease in CoQ[10] production in both recombinant E. coli Ba and E. coli Br strains, as reflected by reductions from 629 +/- 40 to 30 +/- 13 and 564 +/- 28 to 80 +/- 14 micro g/g Dried Cell Weight [DCW], respectively. The results showed high level of FPP reduces endogenous CoQ8 production as well and that CoQs are produced in a complimentary manner, as the increase in production of one decreases the production of the other. The reduction in CoQ[10] production can be a result of Dds inhibition by high FPP concentration. Therefore, more effort is needed to verify the role of intermediate metabolite concentration and to optimize production of CoQ[10]