MAINTENANCE OF INTERNAL PH AND AN ELECTROCHEMICAL GRADIENT IN TRYPANOSOMA-BRUCEI

被引:29
作者
THISSEN, JA
WANG, CC
机构
[1] Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco
关键词
TRYPANOSOMA-BRUCEI; PROTOZOA; C-14]5,5-DIMETHYL-2,4-OXAZOLIDINEDIONE ([C-14]DMO); C-14]METHYL AMINE ([C-14]MEA); H-3]TETRAPHENYL-PHOSPHONIUM BROMIDE ([H-3]TPP+); EXTERNAL PH (PHO); INTERNAL PH (PHI); ELECTRICAL POTENTIAL (DELTA-PSI); PROTON MOTIVE FORCE (DELTA-A-MU-H); CARBONYL CYANIDE META-CHLOROPHENYL HYDRAZONE (CCCP);
D O I
10.1016/0014-4894(91)90143-K
中图分类号
R38 [医学寄生虫学]; Q [生物科学];
学科分类号
07 ; 0710 ; 09 ; 100103 ;
摘要
The internal pH value (pHi) of the long-slender bloodstream form of Trypanosoma brucei was estimated from the distribution of 14C-labeled 5,5-dimethyl-2,4-oxazolidinedione or 14C-labeled methyl amine between the intracellular space of the cells and the medium. The pHi of T. brucei remained relatively constant at 7.0-7.2 throughout an extracellular pH (pHo) range of 6.0-8.0. The maintenance of an internal pH more acidic than the environment appears to be a unique feature. Preincubation of T. brucei with carbonyl cyanide m-chlorophenyl hydrazone (CCCP) or CCCP + valinomycin had no appreciable effect on the ΔpH across the T. brucei membrane when the external pH was 8.O. However, when the external pH was 6.0, CCCP abolished the observed ΔpH. Nigericin significantly dissipated the ΔpH across the T. brucei membrane at all pHo values. These data suggest that under physiological conditions, the maintenance of a ΔpH across the bloodstream-form T. brucei membrane may be by a mechanism other than an energy-dependent gradient, whereas an energy-dependent pump may be needed for maintaining the pHi in an acidic environment. The electrical potential (Δψ) across the trypanosomal plasma membrane was also estimated using the lipophilic cation, [3H]tetraphenyl-phosphonium bromide. It appears dependent on both the external pH and the external salt conditions. Under ionic conditions similar to the host bloodstream, it ranges from -76 to -160 mV over an external pH range of 6.0 to 8.0, with an estimated value of -155.5 ± 0.7 at the physiological pH. It is partially inhibited by N-ethylmaleimide, whereas CCCP, NaN3, NaF, EDTA, and Ca2+ had no effect. The proton motive force (Δa \ ̃gmH) across the membrane of bloodstream form T. brucei is estimated to be about -143.2 mV under physiological conditions, to which Δψ is the main contributing force. © 1991.
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页码:243 / 251
页数:9
相关论文
共 32 条
[21]   PROTON ELECTROCHEMICAL GRADIENT IN ESCHERICHIA-COLI-CELLS [J].
PADAN, E ;
ZILBERSTEIN, D ;
ROTTENBERG, H .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1976, 63 (02) :533-541
[22]   ACTIVE-TRANSPORT OF 2-DEOXY-D-GLUCOSE IN TRYPANOSOMA-BRUCEI PROCYCLIC FORMS [J].
PARSONS, M ;
NIELSEN, B .
MOLECULAR AND BIOCHEMICAL PARASITOLOGY, 1990, 42 (02) :197-203
[23]  
Rottenberg H, 1979, Methods Enzymol, V55, P547
[24]   DETERMINATION OF DELTAPH IN CHLOROPLASTS .1. DISTRIBUTION OF [C-14] METHYLAMINE [J].
ROTTENBERG, H ;
AVRON, M ;
GRUNWALD, T .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1972, 25 (01) :54-+
[25]  
TURRENS JF, 1986, MOL BIOCHEM PARASIT, V19, P259, DOI 10.1016/0166-6851(86)90008-3
[26]   CHANGES IN KINETIC-BEHAVIOR OF THREONINE TRANSPORT INTO TRYPANOSOMA-BRUCEI ELICITED BY VARIATION IN HYDROGEN-ION CONCENTRATION [J].
VOORHEIS, HP .
BIOCHEMICAL JOURNAL, 1977, 164 (01) :15-25
[27]  
WIGGLESWORTH V. B., 1929, PARASITOLOGY, V21, P288, DOI 10.1017/S0031182000022988
[28]   MAINTENANCE OF CYTOPLASMIC PH AND PROTON MOTIVE FORCE IN PROMASTIGOTES OF LEISHMANIA-DONOVANI [J].
ZILBERSTEIN, D ;
PHILOSOPH, H ;
GEPSTEIN, A .
MOLECULAR AND BIOCHEMICAL PARASITOLOGY, 1989, 36 (02) :109-118
[29]   IDENTIFICATION OF A SURFACE-MEMBRANE PROTON-TRANSLOCATING ATPASE IN PROMASTIGOTES OF THE PARASITIC PROTOZOAN LEISHMANIA-DONOVANI [J].
ZILBERSTEIN, D ;
DWYER, DM .
BIOCHEMICAL JOURNAL, 1988, 256 (01) :13-21
[30]   TRICYCLIC DRUGS REDUCE PROTON MOTIVE FORCE IN LEISHMANIA-DONOVANI PROMASTIGOTES [J].
ZILBERSTEIN, D ;
LIVEANU, V ;
GEPSTEIN, A .
BIOCHEMICAL PHARMACOLOGY, 1990, 39 (05) :935-940