A Genome-Scale Metabolic Model of <i>Anabaena</i> 33047 to Guide Genetic Modifications to Overproduce Nylon Monomers
2021
John I. Hendry | Hoang V. Dinh | Debolina Sarkar | Lin Wang | Anindita Bandyopadhyay | Himadri B. Pakrasi | Costas D. Maranas
Nitrogen fixing-cyanobacteria can significantly improve the economic feasibility of cyanobacterial production processes by eliminating the requirement for reduced nitrogen. <i>Anabaena</i> sp. ATCC 33047 is a marine, heterocyst forming, nitrogen fixing cyanobacteria with a very short doubling time of 3.8 h. We developed a comprehensive genome-scale metabolic (GSM) model, <i>i</i>AnC892, for this organism using annotations and content obtained from multiple databases. <i>i</i>AnC892 describes both the vegetative and heterocyst cell types found in the filaments of <i>Anabaena</i> sp. ATCC 33047. <i>i</i>AnC892 includes 953 unique reactions and accounts for the annotation of 892 genes. Comparison of <i>i</i>AnC892 reaction content with the GSM of <i>Anabaena</i> sp. PCC 7120 revealed that there are 109 reactions including uptake hydrogenase, pyruvate decarboxylase, and pyruvate-formate lyase unique to <i>i</i>AnC892. <i>i</i>AnC892 enabled the analysis of energy production pathways in the heterocyst by allowing the cell specific deactivation of light dependent electron transport chain and glucose-6-phosphate metabolizing pathways. The analysis revealed the importance of light dependent electron transport in generating ATP and NADPH at the required ratio for optimal N<sub>2</sub> fixation. When used alongside the strain design algorithm, OptForce, <i>i</i>AnC892 recapitulated several of the experimentally successful genetic intervention strategies that over produced valerolactam and caprolactam precursors.
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