Volume 20, Issue 12 p. 4587-4595
Research article

Regulation of lactate metabolism in the acetogenic bacterium Acetobacterium woodii

Marie Charlotte Schoelmerich

Marie Charlotte Schoelmerich

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

Present address: Department of Microbiology & Biotechnology, University of Hamburg, 22609 Hamburg, Germany.Search for more papers by this author
Alexander Katsyv

Alexander Katsyv

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

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Woung Sung

Woung Sung

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

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Vanessa Mijic

Vanessa Mijic

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

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Anja Wiechmann

Anja Wiechmann

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

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Patrick Kottenhahn

Patrick Kottenhahn

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

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Jonathan Baker

Jonathan Baker

Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), University of Nottingham, Nottingham, UK

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Nigel Peter Minton

Nigel Peter Minton

Clostridia Research Group, BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), University of Nottingham, Nottingham, UK

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Volker Müller

Corresponding Author

Volker Müller

Molecular Microbiology and Bioenergetics, Goethe University Frankfurt, 60438 Frankfurt, Germany

For correspondence. E-mail [email protected]; Tel. (+49) 69 79829507; Fax (+49) 69 79829306.Search for more papers by this author
First published: 17 September 2018
Citations: 27

Summary

Acetogenic bacteria compete in an energy-limited environment by coupling different metabolic routes to their central metabolism of CO2 fixation. The underlying regulatory mechanisms are often still not understood. In this work, we analysed how lactate metabolism is regulated in the model acetogen Acetobacterium woodii. Construction of a ΔlctCDEF mutant and growth analyses demonstrated that the genes are essential for growth on lactate. Subsequent bridging PCR and quantitative PCR analyses revealed that the lctBCDEF genes form an operon that was expressed only during lactate metabolism. The lctA gene was cloned, expressed in Escherichia coli and purified. LctA bound to the intergenic DNA region between lctA and the lct operon in electromobility shift assays, and binding was revoked in the presence of lactate. Further restriction site protection analyses consolidated the lactate-dependent binding of LctA and identified the binding site within the DNA. Cells grew mixotrophically on lactate and another energy source and showed no diauxic growth. From these data, we conclude that the catabolic lactate metabolism is encoded by the lct operon and its expression is negatively regulated by the DNA-binding repressor LctA.