ISSN:
1432-072X
Keywords:
Arthrobacter P1
;
Methylotrophy
;
Membrane vesicles
;
Active transport
;
Methylamine
;
Proton motive force
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Cytoplasmic membrane vesicles were prepared by a lysozyme-salt treatment from Arthrobacter P1 grown on methylamine as the carbon and energy source. In the presence of an ascorbate-phenazine methosulphate electron donor system, these vesicles accumulated methylamine in unmodified form by an inducible transport system. This system has a high affinity for methylamine (Kapp=20–25 μM). The effect of the ionophores valinomycin and nigericin combined with membrane potential (Δψ) and pH-gradient (ΔpH) measurements demonstrated that methylamine uptake is electrogenic and driven by the Δψ. Optimal activity is observed at pH 6.5 and 30°C. Methylamine uptake was not affected by the presence of ammonium ions but was inhibited by the primary amines ethylamine (competitively), propylamine, butylamine and benzylamine. In addition, formaldehyde and acetate, at a concentration of 1 mM, inhibited methylamine uptake almost completely. These compounds were shown to be non-competitive inhibitors. A strong inhibition observed in the presence of plumbagin could be relieved by addition of dithiothreitol. This indicates that the oxidation-reduction state of, probably, carrier dithiol-disulfide-groups is an important factor in methylamine translocation in Arthrobacter P1.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00521287
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