PMC:4301621 / 22592-24759 JSONTXT

{"project":"2_test","denotations":[{"id":"25582171-167775-14905497","span":{"begin":891,"end":893},"obj":"167775"}],"text":"Acetyl-CoA is the essential two-carbon donor molecule for fatty acid synthesis. In model iCY1106, there were ten pathways that could produce acetyl-CoA, including amino acid degradation (from aspartate, isoleucine, leucine, and lysine), fatty acid beta-oxidation, and other acetyl-CoA generation processes (phosphoenolpyruvate [PEP], malate, L-lactate, acetate, and citrate) (Figure 4). However, only the pathway from PEP to pyruvate could generate sufficient flux for synthesis of PUFAs on the fermentation medium. During the growth stage, the flux of acetyl-CoA generated by pyruvate was 1.22 mmol gDW−1 h−1, while this value was 1.56 mmol gDW−1 h−1 during the product synthesis stage. This corresponds to a 27.87% increase, which would ensure acetyl-CoA was available for ARA production due to the enhanced activity of the pyruvate dehydrogenase complex (EC: 1.2.4.1, 2.3.1.12, 1.8.1.4) [37]. Although aspartate, isoleucine, leucine, and lysine could all be used to generate acetyl-CoA for ARA production. Asparate has four carbon, while isoleucine, leucine, and lysine all contains six carbon. When the maximum uptake rate of asparate and the other amino acids were set at 0.15 mmol gDW−1 h−1 and 0.1 mmol gDW−1 h−1, respectively. FBA showed only that leucine and lysine could increase ARA production by 14.06% and 13.28%.\nFigure 4 The sources of acetyl-CoA in M . alpina . (cit: citrate, ac: acetate, llac: l-lactate, mal: malate, pep: phosphoenolpyruvate, pyr: pyruvate, accoa: acrtyl-CoA, asp: l-aspartate, bala: beta-alanine, oppa: 3-oxopropanoate, ile: l-isoleucine, omval: (s)-3-nethyl-2-oxopentanoate, mbcoa: 2-methylbutanoyl-CoA, mcrocoa: 2-methylcrotonoyl-CoA, metbycoa: (2S,3S)-3-Hydroxy-2-methylbutanoyl-CoA, mcecoa: 2-Methylacetoacetyl-CoA, lys: l-lysine, sacp: l-saccharopine, amasa: l-2-aminoadipate 6-semialdehyde, ama: l-2-aminoadipate, aka: 2-oxoadipate, gltcoa: glutaryl-CoA, c4dcoa: crotonoyl-coa, c4hcoa: (S)-3-Hydroxybutanoyl-CoA, aaccoa: acetoacetyl-CoA, leu: l-leucine, 4mop: 4-methyl-2-oxopentanoate, ivacoa: 3-isovaleryl-coa, mcrcoa: 3-nethylcrotonyl-CoA, mgcoa: trans-3-methylglutaconyl-CoA, hmgcoa: (s)-3-hydroxy-3-methylglutaryl-coa)."}