C4-dicarboxylate metabolons: interaction of C4-dicarboxylate transporters of Escherichia coli with cytosolic enzymes

Christopher Schubert, Nam Yeun Kim, Gottfried Unden, Ok Bin Kim

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Metabolons represent the structural organization of proteins for metabolic or regulatory pathways. Here, the interaction of fumarase FumB, aspartase AspA, and L-tartrate dehydratase TtdAB with the C4-dicarboxylate (C4-DC) transporters DcuA, DcuB, DcuC, and the L-tartrate transporter TtdT of Escherichia coli was tested by a bacterial two-hybrid (BACTH) assay in situ, or by co-chromatography using mSPINE (membrane Streptavidin protein interaction experiment). From the general C4-DC transporters, DcuB interacted with FumB and AspA, DcuA with AspA, whereas DcuC interacted with neither FumB nor AspA. Moreover, TtdT did not interact with TtdAB. The fumB-dcuB, the dcuA-aspA, and the ttdAB-ttdT genes encoding the respective proteins colocalize on the genome and each pair of genes forms cotranscripts, whereas the dcuC gene lies alone. The data suggest the formation of DcuB/FumB and DcuB/AspA metabolons for the uptake of L-malate, or L-aspartate, and their conversion to fumarate for fumarate respiration and excretion of the product succinate. The DcuA/AspA metabolon catalyzes uptake and conversion of L-aspartate to fumarate coupled to succinate excretion. The DcuA/AspA metabolon provides ammonia at the same time for nitrogen assimilation (ammonia shuttle). On the other hand, TtdT and TtdAB are not organized in a metabolon. Reasons for the formation (DcuA/AspA, DcuB/FumB, and DcuB/AspA) or nonformation (DcuC, TtdT, and TtdAB) of metabolons are discussed based on their metabolic roles.

Original languageEnglish
Article numberfnac078
JournalFEMS Microbiology Letters
Issue number1
StatePublished - 2022

Bibliographical note

Funding Information:
Acknowledgments We are grateful to Dr A. Strecker (Mainz) for preparing the plasmids with the DcuASWT25 and DcuCSWT25 constructs. Financial support from the Deutsche Forschungsgemeinschaft (grant UN 49/19-1) and from the National Research Foundation of Korea (NRF-2019R1A2C1008066) is gratefully acknowledged

Publisher Copyright:
© 2022 The Author(s). Published by Oxford University Press on behalf of FEMS.


  • C-dicarboxylate transporter
  • Escherichia coli
  • L-aspartate
  • mSPINE
  • metabolon


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