Starvation-induced stimulation of sugar uptake in Streptococcus mutans is due to an effect on the activities of preexisting proteins of the phosphotransferase system.
Starvation-induced stimulation of sugar uptake in Streptococcus mutans is due to an effect on the activities of preexisting proteins of the phosphotransferase system.
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饥饿诱导的变形链球菌糖摄取刺激是由于对磷酸转移酶系统预先存在的蛋白质的活性的影响。
DOI：
10.1128/iai.56.10.2594-2600.1988
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发表时间：
1988
影响因子：
3.1
通讯作者：
Jacobson,GR
中科院分区：
文献类型：
--
作者：
Lodge,J;Jacobson,GR
我们研究了培养基中糖浓度对突变链球菌GS-5糖摄取和磷酸烯醇化酸依赖的糖磷酸转移酶系统（PTS）活性的影响。在蔗糖过量或蔗糖限制条件下收获的细胞中蔗糖摄取的动力学分析表明，在后一种条件下增加的摄取几乎完全是由于高亲和力PTS的Vmax增加。在一系列实验中，将在蔗糖或葡萄糖过量条件下生长的细胞转移到缺乏糖的培养基中，饥饿导致糖摄取的刺激和PTS活性的平行增加。这些饥饿诱导的PTS介导的摄取增加不受氯霉素或利福平的存在下，在饥饿期间，这表明，无论是蛋白质或RNA的合成是必要的刺激。32 Pi的体内标记实验表明，饥饿期间的摄取刺激伴随着与PTS的磷载体蛋白HPr共价结合的酸稳定磷酸盐的损失。因此，我们得出结论，在S.变形链球菌GS-5的表达至少部分是先前存在的PTS蛋白活性增加的结果，这可能至少部分是由于先前鉴定的S.变异株HPr可被ATP依赖性激酶磷酸化。
We examined the effects of sugar concentration in the medium on sugar uptake and phosphoenolpyruvate-dependent sugar phosphotransferase system (PTS) activities in Streptococcus mutants GS-5. Kinetic analyses of sucrose uptake in cells harvested under conditions of sucrose excess or sucrose limitation showed that increased uptake under the latter condition was almost completely due to an increase in the Vmax of the high-affinity PTS. In a series of experiments in which cells growing under conditions of sucrose or glucose excess were shifted to a medium lacking sugar, starvation resulted in a stimulation of sugar uptake and a parallel increase in PTS activity. These starvation-induced increases in PTS-mediated uptake were not affected by the presence of either chloramphenicol or rifampin during the starvation period, indicating that neither protein nor RNA synthesis was necessary for the stimulation. In vivo labeling experiments with 32Pi revealed that uptake stimulation during starvation was accompanied by a loss of acid-stable phosphate covalently bound to the phosphocarrier protein HPr of the PTS. We conclude, therefore, that stimulation of PTS-mediated uptake of sucrose and glucose during sugar limitation in S. mutans GS-5 is at least partially the result of increased activities of preexisting PTS proteins and that this may be due, at least in part, to dephosphorylation of a previously identified site in S. mutans HPr that can be phosphorylated by an ATP-dependent kinase.