ISSN:
1432-072X
Keywords:
Protonmotive force
;
Active transport
;
RuMP-type methylotrophs
;
δpH
;
δΨ
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Formaldehyde accumulation ratios ([14CH2O]i/[14CH2O]o) as high as 12-fold were measured in anaerobic, CH3OH-energized, whole cell suspensions of the ribulose monophosphate (RuMP)-type methylotrophic strain T15. Uptake kinetics were extremely rapid, enabling the attainment of equilibrium in only 10–30 s. Transport appears to be energy-dependent and associated with the protonmotive force (pmf). Anaerobic incubation with 5 μM carbonyl p-(trifluoromethoxy)-phenylhydrazone (FCCP) led to 70%–90% reduction of the accumulation ratio. Though not as pronounced, diminished uptake was also observed in the presence of 140 μM nigericin, 161 μM valinomycin and 90 mM KSCN, commensurate with their effects on pmf. Accumulation of CH2O as a function of external pH followed a trend more similar to that of pmf than either δpH or δΨ. Preventing energization by incubation with 100 μM N,N′-dicyclohexylcarbodiimide (DCCD) led to nearly 80% inhibition of CH2O transport. Over short time periods it was possible to “chase” accumulated 14CH2O from previously loaded cells by collapsing pmf; however, this technique also indicated that significant 14CH2O incorporation began to occur within 3 min.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00422007
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