AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
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 Proctor, L. M.
Right arrow Articles by Gunsalus, R. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Proctor, L. M.
Right arrow Articles by Gunsalus, R. P.
Agricola
Right arrow Articles by Proctor, L. M.
Right arrow Articles by Gunsalus, R. P.

 Previous Article  |  Next Article 

Appl. Environ. Microbiol., Jun 1997, 2252-2257, Vol 63, No. 6
Copyright © 1997, American Society for Microbiology

The methanogenic archaeon Methanosarcina thermophila TM-1 possesses a high-affinity glycine betaine transporter involved in osmotic adaptation

LM Proctor, R Lai and RP Gunsalus
Department of Microbiology and Molecular Genetics, University of California at Los Angeles 90095-1489, USA.

Methanogenic Archaea are found in a wide range of environments and use several strategies to adjust to changes in extracellular solute concentrations. One methanogenic archaeon, Methanosarcina thermophila TM-1, can adapt to various osmotic conditions by synthesis of alpha- glutamate and a newly discovered compatible solute, Ne-acetyl-beta- lysine, or by accumulation of glycine betaine (betaine) and potassium ions from the environment. Since betaine transport has not been characterized for any of the methanogenic Archaea, we examined the uptake of this solute by M. thermophila TM-1. When cells were grown in mineral salts media containing from 0.1 to 0.8 M NaC1, M. thermophila accumulated betaine in concentrations up to 140 times those of a concentration gradient within 10 min of exposure to the solute. The betaine uptake system consisted of a single, high-affinity transporter with an apparent K3 of 10 microM and an apparent maximum transport velocity of 1.15 nmol/min/mg of protein. The transporter appeared to be specific for betaine, since potential substrates, including glycine, sarcosine, dimethyl glycine, choline, and proline, did not significantly inhibit betaine uptake. M. thermophila TM-1 cells can also regulate the capacity for betaine accumulation, since the rate of betaine transport was reduced in cells pregrown in a high-osmolarity medium when 500 microM betaine was present. Betaine transport appears to be H+ and/or Na+ driven, since betaine transport was inhibited by several types of protonophores and sodium ionophores.


This article has been cited by other articles:




Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 1997 by the American Society for Microbiology. All rights reserved.