The effect of environmental pH on the proton motive force of Helicobacter pylori
The effect of environmental pH on the proton motive force of Helicobacter pylori
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DOI：
10.1016/s0016-5085(96)70056-2
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发表时间：
1996-10-01
期刊：
影响因子：
29.4
通讯作者：
Sachs, G
中科院分区：
文献类型：
--
作者：
MeyerRosberg, K;Scott, DR;Sachs, G
背景与目的：幽门螺杆菌的质子动力闹剧（质子的驱动力）对不同培养基pH值的反应可能解释胃定植。本研究的目的是确定外部pH值（pH(out)）对质子动力、pH梯度和细菌膜电位差的影响。方法：采用双羧乙基-羧基荧光素荧光法测定细胞内pH(pH(in))，采用3,3'-二丙基硫代二碳氰碘化物荧光猝灭法测定细胞内跨膜电位差（PD），并与存活相关。结果：PD为-131 +/- 0.36 mV (n = 3)，加载pH(out) 7.0时pH（in）约为8.4。PD随着pH（out）从4.0增加到8.0而增加，质子动力恒定约为-220 mV。在pH为3.0或3.5的弱缓冲液中加入5 mmol/l尿素，通过NH3产生引起的pH升高（out），防止了PD的不可逆塌陷，在pH为7.0的弱缓冲液中加入尿素，随着脲酶活性将pH（out）增加到8.4左右，PD塌陷，存活也被限制在这个pH范围内（out）。结论：幽门螺旋杆菌在pH值范围内存活，并保持质子动力。脲酶活性对pH值的影响，虽然允许胃在酸性培养基中存活，但可能限制非酸性培养基中的存活。
Background & Aims: Responses of the proton motive farce (the driving force for protons) in Helicobacter pylori to varying medium pH may explain gastric colonization. The aim of this study was to determine the effect of external pH (pH(out)) on the proton motive force, the sum of the pH gradient, and the potential difference across the bacterial membrane. Methods: Intracellular pH (pH(in)) was measured by bis-carboxyethyl-carboxyfluorescein fluorescence and transmembrane potential difference (PD) by fluorescent quenching of 3,3'-dipropyl thiadicarbocyanine iodide at differing pH(out) and was correlated with survival, Results: PD was -131 +/- 0.36 mV (n = 3), and pH(in) was about 8.4 at loading pH(out) 7.0. PD increased as pH(out) was increased from 4.0 to 8.0, giving a constant proton motive force of about -220 mV. Outside these limits, PD collapsed irreversibly to zero, Addition of 5 mmol/l urea to weak buffer at pH 3.0 or 3.5 prevented irreversible collapse of PD by elevation of pH(out) caused by NH3 production, Urea addition to weak buffer at pH 7.0 collapsed the PD as urease activity increased the pH(out) to about 8.4, Survival was also limited to this range of pH(out). Conclusions: H. pylori survives over the range of pH(out) where it maintains a proton motive force. The effect of urease activity on pH(out), while allowing gastric survival in acidic media, may limit survival in nonacidic media.