Premium
Rerouting of carbon flux in a glycogen mutant of cyanobacteria assessed via isotopically non‐stationary 13 C metabolic flux analysis
Author(s) -
Hendry John I.,
Prasannan Charulata,
Ma Fangfang,
Möllers K. Benedikt,
Jaiswal Damini,
Digmurti Madhuri,
Allen Doug K.,
Frigaard NielsUlrik,
Dasgupta Santanu,
Wangikar Pramod P.
Publication year - 2017
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.26350
Subject(s) - glycogen , metabolic flux analysis , metabolic network , flux (metallurgy) , biochemistry , cyanobacteria , flux balance analysis , photosynthesis , biology , carbon fibers , pentose phosphate pathway , citric acid cycle , glycogen synthase , glycolysis , metabolism , chemistry , bacteria , genetics , organic chemistry , materials science , composite number , composite material
Cyanobacteria, which constitute a quantitatively dominant phylum, have attracted attention in biofuel applications due to favorable physiological characteristics, high photosynthetic efficiency and amenability to genetic manipulations. However, quantitative aspects of cyanobacterial metabolism have received limited attention. In the present study, we have performed isotopically non‐stationary 13 C metabolic flux analysis (INST‐ 13 C‐MFA) to analyze rerouting of carbon in a glycogen synthase deficient mutant strain ( glgA‐I glgA‐II ) of the model cyanobacterium Synechococcus sp. PCC 7002. During balanced photoautotrophic growth, 10–20% of the fixed carbon is stored in the form of glycogen via a pathway that is conserved across the cyanobacterial phylum. Our results show that deletion of glycogen synthase gene orchestrates cascading effects on carbon distribution in various parts of the metabolic network. Carbon that was originally destined to be incorporated into glycogen gets partially diverted toward alternate storage molecules such as glucosylglycerol and sucrose. The rest is partitioned within the metabolic network, primarily via glycolysis and tricarboxylic acid cycle. A lowered flux toward carbohydrate synthesis and an altered distribution at the glucose‐1‐phosphate node indicate flexibility in the network. Further, reversibility of glycogen biosynthesis reactions points toward the presence of futile cycles. Similar redistribution of carbon was also predicted by Flux Balance Analysis. The results are significant to metabolic engineering efforts with cyanobacteria where fixed carbon needs to be re‐routed to products of interest. Biotechnol. Bioeng. 2017;114: 2298–2308. © 2017 Wiley Periodicals, Inc.