3.1 Assembling IUP pathway in E. coli enables lycopene
production
pC19IUP was first designed for
expression of IUP pathway to test its ability to produce lycopene inE. coli . In this study, IPK from Methanothermobacter
thermautotrophicus (IPKMTH )] and ThiM from Escherichia coli(ThiMEc ) are employed, which was accordingly
under the control of the constitutive promoter PJ23119(BBa_J23119, high strength) (Figure 1B). To better balance the ratio of
IPP and DMAPP, idi from Escherichia coli(idiEc ) was also included. Downstream genes for
lycopene production (CrtE , CrtB , CrtI ) were
co-expressed in pEBI driven by inducible promoter Ptrc(a gift from
Yang). Two strains were obtained, the control strain YZ0 with only MEP
pathway and strain YZ1 with both MEP and IUP pathway. These two strains
were cultivated in LB medium for about 3 h when we added a lower
concentration of IPTG (0.01 mM) in combination with 1g/L prenol as
substrate. When comparing the lycopene titer of two strains after 24
hours’ fermentation, YZ0 produced 0.5 mg/OD600 lycopene,
which was nearly 6.2-fold of the control strain (0.086
mg/OD600), verifying the feasibility of IUP pathway.