Characterization of the ATP synthase of Propionigenium modestum as a primary sodium pump

Journal Article · Tue Sep 20 00:00:00 EDT 1988 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00419a053· OSTI ID:6897679

Laubinger, W; Dimroth, P ^[1]

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1. Technischen Universitaet Muenchen (West Germany)

The ATP synthase (F{sub 1}F{sub 0}) of Propionigenium modestum has been purified to a specific ATPase activity of 5.5 units/mg of protein, which is about 6 times higher than that of the bacterial membranes. Analysis by SDS gel electrophoresis indicated that in addition to the five subunits of the F{sub 1} ATPase, subunits of M{sub r} 26,000 (a), 23,000 (b), and 7,500 (c) have been purified. The ATPase activity of F{sub 1}F{sub 0} was specifically activated about 10-fold by Na{sup +} ions. The enzyme was strongly inhibited by dicyclohexylcarbodiimide, venturicidin, tributyltin chloride, and azide. After incubation with ({sup 14}C)dicyclohexylcarbodiimide, about 3-4 mol of the inhibitor was bound per 500,000 g of the enzyme. The radioactive label was specifically bound to subunit c. These subunits form stable aggregates which resist dissociation by SDS at 100{degree}C. The monomer is formed upon heating with SDS to 121{degree}C or by extraction of the membranes with chloroform/methanol. The ATP synthase was incorporated into liposomes by a freeze-thaw-sonication procedure. The reconstituted proteoliposomes catalyzed the transport of Na{sup +} ions upon ATP hydrolysis. The transport was completely abolished by dicyclohexylcarbodiimide. Whereas monensin prevented the accumulation of Na{sup +} ions, the uptake rate was stimulated 4-5-fold in the presence of valinomycin or carbonyl cyanide m-chlorophenylhydrazone. These results indicate an electrogenic Na{sup +} transport and also that it is a primary event and not accomplished by a H{sup +}-translocating ATP synthase in combination with a Na{sup +}/H{sup +} antiporter.

• OSTI ID: 6897679
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 27:19; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ALKALI METAL COMPOUNDS
ANAEROBIC CONDITIONS
ATP-ASE
BACTERIA
BIOLOGICAL PATHWAYS
CARBON 14 COMPOUNDS
CELL CONSTITUENTS
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
HYDROLASES
IMIDES
INHIBITION
LABELLED COMPOUNDS
LIPOSOMES
MICROORGANISMS
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOIDS
PHOSPHOHYDROLASES
SODIUM COMPOUNDS
UPTAKE