Dissolved Inorganic Carbon-Accumulating Complexes from Autotrophic Bacteria from Extreme Environments

Sarah Schmid, Dale Chaput, Mya Breitbart, Rebecca Hines, Samantha Williams, Hunter K. Gossett, Sheila D. Parsi, Rebecca Peterson, Robert A. Whittaker, Angela Tarver, Kathleen M. Scott

Research output: Contribution to journalArticlepeer-review

Abstract

In nature, concentrations of dissolved inorganic carbon (DIC; CO 2 + HCO 3 + CO 3 2− ) can be low, and autotrophic organisms adapt with a variety of mechanisms to elevate intracellular DIC concentrations to enhance CO 2 fixation. Such mechanisms have been well studied in Cyanobacteria , but much remains to be learned about their activity in other phyla. Novel multisubunit membrane-spanning complexes capable of elevating intracellular DIC were recently described in three species of bacteria. Homologs of these complexes are distributed among 17 phyla in Bacteria and Archaea and are predicted to consist of one, two, or three subunits. To determine whether DIC accumulation is a shared feature of these diverse complexes, seven of them, representative of organisms from four phyla, from a variety of habitats, and with three different subunit configurations, were chosen for study. A high-CO 2 -requiring, carbonic anhydrase-deficient (Δ yadF Δ cynT ) strain of Escherichia coli Lemo21(DE3), which could be rescued via elevated intracellular DIC concentrations, was created for heterologous expression and characterization of the complexes. Expression of all seven complexes rescued the ability of E. coli Lemo21(DE3) Δ yadF Δ cynT to grow under low-CO 2 conditions, and six of the seven generated measurably elevated intracellular DIC concentrations when their expression was induced. For complexes consisting of two or three subunits, all subunits were necessary for DIC accumulation. Isotopic disequilibrium experiments clarified that CO 2 was the substrate for these complexes. In addition, the presence of an ionophore prevented the accumulation of intracellular DIC, suggesting that these complexes may couple proton potential to DIC accumulation.

Original languageAmerican English
JournalJournal of Bacteriology
Volume203
DOIs
StatePublished - Jan 1 2021

Keywords

  • autotroph
  • carbon dioxide
  • carbon dioxide-concentrating mechanism
  • carbon fixation
  • dissolved inorganic carbon

Disciplines

  • Life Sciences

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