Biology Reference
In-Depth Information
197
FIGURE 10.3
Engineered pathways in highest amorphadiene producing E. coli (left) and S. cerevisiae (right) strains. Sources of genes are
in italics under gene names. Enzymes encoded by genes: atoB and ERG10, acetoacetyl-CoA thiolase; mvaS and ERG13,
HMG-CoA synthase; mvaA, HMG-CoA reductase; tHMG1, truncated HMG-CoA reductase; ERG12, mevalonate kinase; ERG8,
phosphomevalonate kinase; ERG19, mevalonate pyrophosphate decarboxylase; idi and IDI1, IPP isomerase; ispA and ERG20,
farnesyl pyrophosphate synthase; ADS, amorphadiene synthase.
Engineering on the MevT genes has also led to considerable increase in concentrations.
Studies showed that hydroxymethylglutaryl-CoA (HMG-CoA), an intermediate in the upper
stage of the mevalonate pathway, inhibits cell growth.
179
Tsuruta and coworkers swapped
the HMG-CoA synthase and reductase genes originally from yeast with those from
Staphylococcus aureus
, producing around 275 mg/L amorphadiene compared to 223 mg/L
without the swapped genes.
180
It should be noted that titers listed are from shake flask
cultures, and that improvements in fermentation process and compound separation led to
amorphadiene production of over 25 g/L in
E. coli
.
180
Considerable engineering has been done on yeast
s native mevalonate pathway to give
amorphadiene titers comparable with those in
E. coli
. Along with the overexpression of
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