Increased Hydrogen Production by Genetic Engineering of Escherichia coli - Genetic Engineering: Recent Developments in Applications - page 3

expression of selC gene which encodes a tRNA for the incorporation of seleno-
cysteine to FDHH (Table 1) [8], [11], [21].
Figure 1. The genetic modification of metabolic pathways and regulatory components for hydrogen production
in E. coli. The metabolic flows are indicated by solid arrows. Some key enzyme systems are labeled. The key
global regulators and their regulatory targets are circled and indicated by dashed arrows, respectively. Pluses (+)
represent activation, and minuses (−) represent repression. Crosses (X) indicate chromosomal gene disruptions.
Table 1. Genes engineered in this study, and their functions.
Successful efforts to redirect pyruvate towards hydrogen in E. coli, have in-
volved the up-regulation of the FHL complex and the disruption of pathways
competing for pyruvate [4], [22]-[24]. It is estimated that over 50 genes distrib-
uted across at least 20 distinct genetic loci define fermentative hydrogen metabo-
lism in E. coli [8]. In this study, our strategy involves the systematic modification
of multiple, discrete, metablic segments that include global regulatory, transport,
and auxiliary components required for FHL biosynthesis, processing and assem-
bly. The modification of key regulatory elements represents a practical strategy
for the coordinated engineering of genes and operons that perform distinct bio-
chemical functions related to the production of hydrogen. This approach has the
potential to achieve the balance of cofactor and precursor supply pathways with