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 Schröder, I.
Right arrow Articles by Monbouquette, H. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Schröder, I.
Right arrow Articles by Monbouquette, H. G.

 Previous Article  |  Next Article 

Journal of Bacteriology, November 2004, p. 7680-7689, Vol. 186, No. 22
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.22.7680-7689.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

A Novel Archaeal Alanine Dehydrogenase Homologous to Ornithine Cyclodeaminase and µ-Crystallin

Imke Schröder,1* Alexander Vadas,2 Eric Johnson,1 Sierin Lim,2 and Harold G. Monbouquette2*

Department of Microbiology, Immunology and Molecular Genetics,1 Department of Chemical Engineering, University of California, Los Angeles, California2

Received 6 May 2004/ Accepted 16 August 2004

A novel alanine dehydrogenase (AlaDH) showing no significant amino acid sequence homology with previously known bacterial AlaDHs was purified to homogeneity from the soluble fraction of the hyperthermophilic archaeon Archaeoglobus fulgidus. AlaDH catalyzed the reversible, NAD+-dependent deamination of L-alanine to pyruvate and NH4+. NADP(H) did not serve as a coenzyme. The enzyme is a homodimer of 35 kDa per subunit. The Km values for L-alanine, NAD+, pyruvate, NADH, and NH4+ were estimated at 0.71, 0.60, 0.16, 0.02, and 17.3 mM, respectively. The A. fulgidus enzyme exhibited its highest activity at about 82°C (203 U/mg for reductive amination of pyruvate) yet still retained 30% of its maximum activity at 25°C. The thermostability of A. fulgidus AlaDH was increased by more than 10-fold by 1.5 M KCl to a half-life of 55 h at 90°C. At 25°C in the presence of this salt solution, the enzyme was ~100% stable for more than 3 months. Closely related A. fulgidus AlaDH homologues were found in other archaea. On the basis of its amino acid sequence, A. fulgidus AlaDH is a member of the ornithine cyclodeaminase-µ-crystallin family of enzymes. Similar to the µ-crystallins, A. fulgidus AlaDH did not exhibit any ornithine cyclodeaminase activity. The recombinant human µ-crystallin was assayed for AlaDH activity, but no activity was detected. The novel A. fulgidus gene encoding AlaDH, AF1665, is designated ala.

* Corresponding author. Mailing address for I.S.: Department of Microbiology, Immunology and Molecular Genetics, 1602 Molecular Sciences Bldg., Los Angeles, CA 90095-1489. Phone: (310) 825-8085. Fax: (310) 206-5231. E-mail: imkes{at}microbio.ucla.edu. Mailing address for H.G.M.: Chemical Engineering Department, 5531 Boelter Hall, University of California, Los Angeles, CA 90095. Phone: (310) 825-8946. Fax: (310) 206-4107. E-mail: hmonbouq{at}ucla.edu.

Journal of Bacteriology, November 2004, p. 7680-7689, Vol. 186, No. 22
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.22.7680-7689.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Brady, R. A., Leid, J. G., Camper, A. K., Costerton, J. W., Shirtliff, M. E. (2006). Identification of Staphylococcus aureus Proteins Recognized by the Antibody-Mediated Immune Response to a Biofilm Infection.. Infect. Immun. 74: 3415-3426 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»