Previous Article | Next Article ![]()
Applied and Environmental Microbiology, March 1999, p. 1191-1197, Vol. 65, No. 3
Department of Biology, University Plaza,
Georgia State University, Atlanta, Georgia 30302-4010
Received 12 August 1998/Accepted 7 December 1998
The influence of modified plasma membrane fatty acid composition on
cellular strontium accumulation in Saccharomyces cerevisiae was investigated. Growth of S. cerevisiae in the
presence of 1 mM linoleate (18:2) (which results in 18:2
incorporation to ~70% of total cellular and plasma membrane fatty
acids, with no effect on growth rate) yielded cells that accumulated
Sr2+ intracellularly at approximately twice the rate of
S. cerevisiae grown without a fatty acid supplement.
This effect was evident over a wide range of external Sr2+
concentrations (25 µM to 5 mM) and increased with the extent of
cellular 18:2 incorporation. Stimulation of Sr2+
accumulation was not evident following enrichment of S. cerevisiae with either palmitoleate (16:1), linolenate (18:3)
(n-3 and n-6 isomers), or eicosadienoate (20:2)
(n-6 and n-9 isomers). Competition experiments
revealed that Ca2+- and Mg2+-induced inhibition
of Sr2+ accumulation did not differ between unsupplemented
and 18:2-supplemented cells. Treatment with trifluoperazine (TFP)
(which can act as a calmodulin antagonist and
Ca2+-ATPase inhibitor), at a low concentration
that precluded nonspecific K+ efflux, increased
intracellular Sr2+ accumulation by approximately 3.6- and
1.4-fold in unsupplemented and 18:2-supplemented cells, respectively.
Thus, TFP abolished the enhanced Sr2+ accumulation ability
of 18:2-supplemented cells. Moreover, the rate of Sr2+
release from Sr2+-loaded fatty acid-unsupplemented cells
was found to be at least twice as great as that from
Sr2+-loaded 18:2-enriched cells. The influence of
enrichment with other fatty acids on Sr2+ efflux was
variable. The results reveal an enhanced Sr2+ accumulation
ability of S. cerevisiae following 18:2-enrichment, which is attributed to diminished Sr2+ efflux activity in
these cells.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Stimulation of Strontium Accumulation in
Linoleate-Enriched Saccharomyces cerevisiae Is a Result
of Reduced Sr2+ Efflux
and
*
Corresponding author. Mailing address: Department of
Biology, University Plaza, Georgia State University, Atlanta, GA
30302-4010. Phone: (404) 651-0912. Fax: (404) 651-2509. E-mail:
biosva{at}panther.gsu.edu.
Permanent address: Department of Geology, Georgia State University,
Atlanta, GA 30303.
Present address: Unilever RED, Port Sunlight Laboratory,
Bebbington, Merseyside L63 3JW, United Kingdom.
| J. Bacteriol. | Microbiol. Mol. Biol. Rev. | Eukaryot. Cell | All ASM Journals |
|---|