ISSN:
1432-072X
Schlagwort(e):
Streptococcus mutans
;
Protonmotive force
;
Sugar transport
;
Chemostat culture
;
Dental disease
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract Streptococcus mutans Ingbritt was grown in glucose-excess continuous culture to repress the glucose phosphoenolpyruvate phosphotransferase system (PTS) and allow investigation of the alternative glucose process using the non-PTS substrate, (3H) 6-deoxyglucose. After correcting for non-specific adsorption to inactivated cells, the radiolabelled glucose analogue was found to be concentrated approximately 4.3-fold intracellularly by bacteria incubated in 100 mM Tris-citrate buffer, pH 7.0. Mercaptoethanol or KCl enhanced 6-deoxyglucose uptake, enabling it to be concentrated internally by at least 8-fold, but NaCl was inhibitory to its transport. Initial uptake was antagonised by glucose but not 2-deoxyglucose. Evidence that 6-deoxyglucose transport was driven by protonmotive force (Δp) was obtained by inhibiting its uptake with the protonophores, 2,4-dinitrophenol, carbonylcyanide m-chlorophenylhydrazine, gramicidin and nigericin, and the electrical potential difference (ΔΨ) dissipator, KSCN. The membrane ATPase inhibitor, N,N1-dicyclohexyl carbodiimide, also reduced 6-deoxyglucose uptake as did 100 mM lactate. In combination, these two inhibitors completely abolished 6-deoxyglucose transport. This suggests that the driving force for 6-deoxyglucose uptake is electrogenic, involving both the transmembrane pH gradient (ΔpH) and ΔΨ. ATP hydrolysis, catalysed by the ATPase, and lactate excretion might be important contributors to ΔpH.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00402337
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