Cyanobacterial carboxysome mutant analysis reveals the influence of enzyme compartmentalization on cellular metabolism and metabolic network rigidity [electronic resource]

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Tác giả:

Ngôn ngữ: eng

Ký hiệu phân loại: 333.85 Minerals

Thông tin xuất bản: Golden, Colo. : Oak Ridge, Tenn. : National Renewable Energy Laboratory (U.S.) ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2019

Mô tả vật lý: Size: p. 222-231 : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 262829

 Cyanobacterial carboxysomes encapsulate carbonic anhydrase and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Genetic deletion of the major structural proteins encoded within the <
 em>
 ccm<
 /em>
  operon in <
 em>
 Synechococcus<
 /em>
  sp. PCC 7002 (<
 em>
 ?ccmKLMN<
 /em>
 ) disrupts carboxysome formation and significantly affects cellular physiology. In this study, we employed both metabolite pool size analysis and isotopically nonstationary metabolic flux analysis (INST-MFA) to examine metabolic regulation in cells lacking carboxysomes. Under high CO<
 sub>
 2<
 /sub>
  environments (1%), the <
 em>
 ?ccmKLMN<
 /em>
  mutant could recover growth and had a similar central flux distribution as the control strain, with the exceptions of moderately decreased photosynthesis and elevated biomass protein content and photorespiration activity. Metabolite analyses indicated that the <
 em>
 ?ccmKLMN<
 /em>
  strain had significantly larger pool sizes of pyruvate (>
 18 folds), UDPG (uridine diphosphate glucose), and aspartate as well as higher levels of secreted organic acids (e.g., malate and succinate). These results suggest that the <
 em>
 ?ccmKLMN<
 /em>
  mutant is able to largely maintain a fluxome similar to the control strain by changing in intracellular metabolite concentrations and metabolite overflows under optimal growth conditions. When CO<
 sub>
 2<
 /sub>
  was insufficient (0.2%), provision of acetate moderately promoted mutant growth. Interestingly, the removal of microcompartments may loosen the flux network and promote RuBisCO side-reactions, facilitating redirection of central metabolites to competing pathways (i.e., pyruvate to heterologous lactate production). This study provides important insights into metabolic regulation via enzyme compartmentation and cyanobacterial compensatory responses.
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