Team:SDU-Denmark/Tour31

Specifications

Rewiring of the E. coli machinery

MEP pathway The biosynthesis of isoprenoids in bacteria works through the methylerythritol phosphate pathway (MEP pathway). The pathway is initiated with a condensation reaction between D-glyceraldehyde 3-phosphate and pyruvate to produce DXP 1-deoxy-D-xylulose-5-phosphate and CO2 catalysed by Dxs. 1-deoxyxylulose-5-phosphate synthase

DXP is reductively isomerized to MEP 2-C-methyl-D-erythritol-4-phosphate by Dxr 1-deoxy-D-xylulose-5-phosphate reductoisomerase in a reversible NADPH-dependent reaction and subsequently converted to CDP-ME 4-diphosphocytidyl-2-C-methyl-D-erythritol in a CTP substrate inhibited reaction catalysed by IspD. 4-diphosphocytidyl-2-C-methyl-D-erythritol synthase

DXP is not only a substrate in the isoprenoids biosynthesis, but also for the reversible synthesis of B1-vitamin and further synthesis of B6-vitamin in the thiamine biosynthesis pathway.

The next step in the MEP pathway is an ATP-dependent phosphorylation of the C2 hydroxyl group of CDP-ME, giving CDP-MEP 4-diphosphocytidyl-2-C-methyl-D-erythritol-2-phosphate catalysed by IspE. 4-diphosphocytidyl-2-C-methyl-D-erythritol kinase

CDP-MEP is cyclized to MEcPP 2-C-methyl-D-erythritol-2,4-cyclodiphosphat by IspF 2-C-methyl-D-erythritol-2,4-cyclodiphosphate synthase and in the next reaction IspG 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase catalyzes the ring opening of the cyclic pyrophosphate and subsequent C3-reductive dehydration of MEcPP to HMBPP. 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate