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PdhR (pyruvate dehydrogenase complex regulator) controls the respiratory electron transport system in Escherichia

Hiroshi Ogasawara1, Yuji Ishida, Kayoko Yamada

  • 1Department of Frontier Bioscience, Hosei University, Kajino-cho 3-7-2, Koganei, Tokyo 184-8584, Japan.

Journal of Bacteriology
|May 22, 2007
PubMed

Insights

PdhR regulates the pyruvate dehydrogenase (PDH) complex and respiratory electron transport in E. coli. This transcription regulator controls genes for PDH, NADH dehydrogenase II, and cytochrome bo-type oxidase, linking metabolism and respiration.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • The pyruvate dehydrogenase (PDH) complex links glycolysis to the citric acid cycle.
  • PdhR, a GntR family regulator, controls the PDH operon in Escherichia coli, responding to pyruvate levels.

Purpose of the Study:

  • To identify novel PdhR regulatory targets beyond the PDH complex.
  • To elucidate the role of PdhR in regulating respiratory electron transport pathways.

Main Methods:

  • Genomic systematic evolution of ligands by exponential enrichment (SELEX) to identify PdhR binding sites.
  • Gel shift and DNase I footprinting assays to characterize PdhR-DNA interactions.
  • In vivo promoter assays using a two-fluorescent-protein vector to assess gene regulation.

Main Results:

  • Two new PdhR targets identified: ndh (NADH dehydrogenase II) and cyoABCDE (cytochrome bo-type oxidase).
  • The PdhR binding site (PdhR box) with a consensus sequence (ATTGGTNNNACCAAT) was defined.
  • PdhR binding decreased with pyruvate; PdhR repressed ndh and cyoABCDE expression, which was derepressed by pyruvate.

Conclusions:

  • PdhR acts as a master regulator for both the PDH complex and the respiratory electron transport system in E. coli.
  • PdhR integrates metabolic status (pyruvate levels) with the control of central carbon metabolism and energy generation pathways.

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