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Journal of Bacteriology, November 2006, p. 7668-7676, Vol. 188, No. 21
0021-9193/06/$08.00+0     doi:10.1128/JB.01009-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Knockout and Overexpression of Pyrroloquinoline Quinone Biosynthetic Genes in Gluconobacter oxydans 621H{triangledown}

Tina Hölscher* and Helmut Görisch

Fachgebiet Technische Biochemie, Institut für Biotechnologie, Technische Universität Berlin, D-13353 Berlin, Germany

Received 10 July 2006/ Accepted 17 August 2006

In Gluconobacter oxydans, pyrroloquinoline quinone (PQQ) serves as the cofactor for various membrane-bound dehydrogenases that oxidize sugars and alcohols in the periplasm. Proteins for the biosynthesis of PQQ are encoded by the pqqABCDE gene cluster. Our reverse transcription-PCR and promoter analysis data indicated that the pqqA promoter represents the only promoter within the pqqABCDE cluster of G. oxydans 621H. PQQ overproduction in G. oxydans was achieved by transformation with the plasmid-carried pqqA gene or the complete pqqABCDE cluster. A G. oxydans mutant unable to produce PQQ was obtained by site-directed disruption of the pqqA gene. In contrast to the wild-type strain, the pqqA mutant did not grow with D-mannitol, D-glucose, or glycerol as the sole energy source, showing that in G. oxydans 621H, PQQ is essential for growth with these substrates. Growth of the pqqA mutant, however, was found with D-gluconate as the energy source. The growth behavior of the pqqA mutant correlated with the presence or absence of the respective PQQ-dependent membrane-bound dehydrogenase activities, demonstrating the vital role of these enzymes in G. oxydans metabolism. A different PQQ-deficient mutant was generated by Tn5 transposon mutagenesis. This mutant showed a defect in a gene with high homology to the Escherichia coli tldD gene, which encodes a peptidase. Our results indicate that the tldD gene in G. oxydans 621H is involved in PQQ biosynthesis, possibly with a similar function to that of the pqqF genes found in other PQQ-synthesizing bacteria.

* Corresponding author. Mailing address: FG Technische Biochemie, Sekr. GG1, TU Berlin, Seestr. 13, D-13353 Berlin, Germany. Phone: 49 30 31427509. Fax: 49 30 31427581. E-mail: Tina.Hoelscher{at}TU-berlin.de.

{triangledown} Published ahead of print on 25 August 2006.

Journal of Bacteriology, November 2006, p. 7668-7676, Vol. 188, No. 21
0021-9193/06/$08.00+0     doi:10.1128/JB.01009-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Guo, Y. B., Li, J., Li, L., Chen, F., Wu, W., Wang, J., Wang, H. (2009). Mutations That Disrupt Either the pqq or the gdh Gene of Rahnella aquatilis Abolish the Production of an Antibacterial Substance and Result in Reduced Biological Control of Grapevine Crown Gall. Appl. Environ. Microbiol. 75: 6792-6803 [Abstract] [Full Text]  
  • Holscher, T., Weinert-Sepalage, D., Gorisch, H. (2007). Identification of membrane-bound quinoprotein inositol dehydrogenase in Gluconobacter oxydans ATCC 621H. Microbiology 153: 499-506 [Abstract] [Full Text]  


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