Studying On The Efficient Of Synthesis Coenzyme Q₁₀Metabolic Mechanism In Rhodobacter Sphaeroides 2.4.1

Coenzyme Q10(CoQ10),also called ubiquinone is an essential lipid-soluble component to bacterial respiratory chains.In recent years,the study found that coenzyme Q10 combined with other drugs has huge potential in clinical treatment of cardiovascular and cerebrovascular diseases.Therefore,improving the yield of coenzyme Q10 has always been a research hotspot in bacteria.In prokaryotic organisms,the synthesis of coenzyme Q10 is mainly composed by side chain synthesis pathway(MEP or MVA pathway),shikimic acid synthesis pathway and quinone ring modification pathway.The side chain and shikimic acid metabolic pathway are important precursors of coenzyme Q10 synthesis which are mainly synthesized by decaisoprene pyrophosphate(DPP)and p-hydroxybenzoic acid(pHBA),respectively.In this paper,Rhodobacter sphaeroides 2.4.1 was used as the research model to increase the accumulation of precursors and the production of coenzyme Q10 by modifying metabolic flow.The main research results are as follows:(1)Knocked out pykA,RSP-1848 and double knocked out pykA/RSP-1848 in R.sphaeroides 2.4.1,it was found that knockout RSP-1848 could increase the production of coenzyme Q10 about 45.8%compared with wild strain,while knockout pykA and pykA/RSP-1848 reduced the production of coenzyme Q10 by 33.63%and 40.60%,respectively.(2)By overexpressing pyruvate phosphokinase ppdk,transketase gene tktA,3-deoxy-arabinose-heptanone-7-phosphate synthase RSP-2921 and shikimic acid kinase arok in RSP-1848 knockout strain,the effects of coenzyme Q10 synthesis were further studied.And the results showed that overexpression of 3-deoxy-arabinose-7-phosphate synthase RSP-2921 could enhance the biomass about 17%,but the yield of coenzyme Q10 decreased by 24.8%.While overexpression of shikimic acid kinase arok increased the yield of coenzyme Q10 about 17%,but the biomass did not increase.(3)In order to further study the effect of related genes to chorismate metabolism pathway on the synthesis of coenzyme Q10,the chorismate acid lyase gene ubic and 4-hydroxybenzoate octaprenyltransferase gene ubiA were expressed by heterologous expression in the later stage.Overexpression of ubic gene increased biomass about 30%compared with wild type,but decreased yield of coenzyme Q10 about 15%.In conclusion,increasing the carbon flux of chorismate metabolism pathway could enhance the production of coenzyme Q10;Arok is a key gene of regulates the shikimic acid metabolism pathway;Heterogenous overexpression of ubic-ubiAEcoli gene could enhance the catalytic synthesis of PHB and DPP and improve the synthesis of coenzyme Q10?...