JB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Vorholt, J. A.
Right arrow Articles by Thauer, R. K.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Vorholt, J. A.
Right arrow Articles by Thauer, R. K.

 Previous Article  |  Next Article 

Journal of Bacteriology, October 1998, p. 5351-5356, Vol. 180, No. 20
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.

The NADP-Dependent Methylene Tetrahydromethanopterin Dehydrogenase in Methylobacterium extorquens AM1

Julia A. Vorholt,1,* Ludmila Chistoserdova,2 Mary E. Lidstrom,2 and Rudolf K. Thauer1

Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie des Fachbereichs Biologie der Philipps-Universität, 35043 Marburg, Germany,1 and Department of Chemical Engineering, University of Washington, Seattle, Washington 981952

Received 9 June 1998/Accepted 12 August 1998

An NADP-dependent methylene tetrahydromethanopterin (H4MPT) dehydrogenase has recently been proposed to be involved in formaldehyde oxidation to CO2 in Methylobacterium extorquens AM1. We report here on the purification of this novel enzyme to apparent homogeneity. Via the N-terminal amino acid sequence, it was identified to be the mtdA gene product. The purified enzyme catalyzed the dehydrogenation of methylene H4MPT with NADP+ rather than with NAD+, with a specific activity of approximately 400 U/mg of protein. It also catalyzed the dehydrogenation of methylene tetrahydrofolate (methylene H4F) with NADP+. With methylene H4F as the substrate, however, the specific activity (26 U/mg) and the catalytic efficiency (Vmax/Km) were approximately 20-fold lower than with methylene H4MPT. Whereas the dehydrogenation of methylene H4MPT (E0 = -390 mV) with NADP+ (E0 = -320 mV) proceeded essentially irreversibly, the dehydrogenation of methylene H4F (E0 = -300 mV) was fully reversible. Comparison of the primary structure of the NADP-dependent dehydrogenase from M. extorquens AM1 with those of methylene H4F dehydrogenases from other bacteria and eucarya and with those of methylene H4MPT dehydrogenases from methanogenic archaea revealed only marginally significant similarity (<15%).

* Corresponding author. Mailing address: Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Straße, 35043 Marburg, Germany. Phone: 49-6421-178331. Fax: 49-6421-178299. E-mail: vorholt{at}mailer.uni-marburg.de.

Journal of Bacteriology, October 1998, p. 5351-5356, Vol. 180, No. 20
0021-9193/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
Appl. Environ. Microbiol. Infect. Immun. Eukaryot. Cell
Mol. Cell. Biol. J. Virol. Microbiol. Mol. Biol. Rev.
ALL ASM JOURNALS

Copyright © 1998 by the American Society for Microbiology. All rights reserved.