Zvyagilskaya R, Parchomenko O, Abramova N, Allard P, Panaretakis T, Pattison-Granberg J, Persson B L
A.N. Bach Institute of Biochemistry, Russian Academy of Sciences, Leninsky pr. 33, Moscow 117071, Russia.
J Membr Biol. 2001 Sep 1;183(1):39-50. doi: 10.1007/s00232-001-0054-9.
In this study we have used a newly isolated Yarrowia lipolytica yeast strain with a unique capacity to grow over a wide pH range (3.5-10.5), which makes it an excellent model system for studying H(+)- and Na(+)-coupled phosphate transport systems. Even at extreme growth conditions (low concentrations of extracellular phosphate, alkaline pH values) Y. lipolytica preserved tightly-coupled mitochondria with the fully competent respiratory chain containing three points of energy conservation. This was demonstrated for the first time for cells grown at pH 9.5-10.0. In cells grown at pH 4.5, inorganic phosphate (P(i)) was accumulated by two kinetically discrete H(+)/P(i)-cotransport systems. The low-affinity system is most likely constitutively expressed and operates at high P(i) concentrations. The high-affinity system, subjected to regulation by both extracellular P(i) availability and intracellular polyphosphate stores, is mobilized during P(i)-starvation. In cells grown at pH 9.5-10, P(i) uptake is mediated by several kinetically discrete Na(+)-dependent systems that are specifically activated by Na(+) ions and insensitive to the protonophore CCCP. One of these, a low-affinity transporter operative at high P(i) concentrations is kinetically characterized here for the first time. The other two, high-affinity, high-capacity systems, are derepressible and functional during P(i)-starvation and appear to be controlled by extracellular P(i). They represent the first examples of high-capacity, Na(+)-driven P(i) transport systems in an organism belonging to neither the animal nor bacterial kingdoms. The contribution of the H(+)- and Na(+)-coupled P(i) transport systems in Y. lipolytica cells grown at different pH values was quantified. In cells grown at pH values of 4.5 and 6.0, the H(+)-coupled P(i) transport systems are predominant. The contribution of the Na(+)/P(i) cotransport systems to the total cellular P(i) uptake activity is progressively increased with increasing pH, reaching its maximum at pH 9 and higher.
在本研究中，我们使用了一种新分离的解脂耶氏酵母菌株，它具有在很宽的pH范围（3.5 - 10.5）内生长的独特能力，这使其成为研究H⁺和Na⁺偶联的磷酸盐转运系统的优秀模型系统。即使在极端生长条件下（细胞外磷酸盐浓度低、碱性pH值），解脂耶氏酵母仍保留紧密偶联的线粒体，其呼吸链功能完全正常，包含三个能量守恒点。这首次在pH 9.5 - 10.0条件下生长的细胞中得到证实。在pH 4.5条件下生长的细胞中，无机磷酸盐（P(i)）通过两个动力学上不同的H⁺/P(i)共转运系统积累。低亲和力系统很可能是组成型表达的，在高P(i)浓度下起作用。高亲和力系统受细胞外P(i)可用性和细胞内多磷酸盐储存的双重调节，在P(i)饥饿期间被激活。在pH 9.5 - 10条件下生长的细胞中，P(i)摄取由几个动力学上不同的Na⁺依赖性系统介导，这些系统被Na⁺离子特异性激活，对质子载体CCCP不敏感。其中之一，一种在高P(i)浓度下起作用的低亲和力转运蛋白，在此首次进行了动力学表征。另外两个高亲和力、高容量系统是可去阻遏的，在P(i)饥饿期间起作用，似乎受细胞外P(i)控制。它们代表了在既不属于动物界也不属于细菌界的生物体中首次发现高容量、Na⁺驱动的P(i)转运系统的例子。对在不同pH值下生长的解脂耶氏酵母细胞中H⁺和Na⁺偶联的P(i)转运系统的贡献进行了量化。在pH值为
