ISSN:
1432-072X
Keywords:
Potassium transport
;
High-affinity transport system
;
Kdp-ike potassium ATPase
;
Expression
;
Immunological cross-reactivity
;
Internal pH regulation
;
Photosynthetic bacteria (Rhodobacter sphaeroides, Rhodobacter capsulatus and Rhodospirillum rubrum)
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Cells of the purple non-sulphur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. Antibodies againts the catalytic KdpB protein or the whole KdpABC complex of Escherichia coli crossreact with a 70.0 kDa R. sphaeroides protein that was expressed only in cells grown in media with low K+ concentrations. In membranes derived from R. sphaeroides cells grown with low K+ concentrations (induced cells), a high ATPase activity could be detected when assayed in Tris-HCl pH 8.0 containing 1 mM MgSO4. This ATPase activity increased upon addition of 1 mM KCl from 166 to 289 μmol ATP hydrolysed x min-1 x g protein-1 (1.7-fold stimulation). The K+-stimulated ATPase activity was inhibited approximately 93% by 0.5 mM vanadate but hardly by N,N′-dicyclohexylcarbo-diimide (DCCD). These results indicate that the inducible K+-ATPase in R. sphaeroides resembles the Kdp K+-translocating ATPase of Escherichia coli. This Kdp-like transport system is also expressed in R. capsulatus and Rhodospirillum rubrum during growth in media with low K+ concentrations suggesting a wide distribution of this transport system among phototrophic bacteria.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00245368
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