CARRIER-MEDIATED UPTAKE OF ARGININE AND UREA BY CHLAMYDOMONAS-REINHARDTII
CARRIER-MEDIATED UPTAKE OF ARGININE AND UREA BY CHLAMYDOMONAS-REINHARDTII
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DOI：
10.1104/pp.61.4.556
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发表时间：
1978-01-01
期刊：
影响因子：
7.4
通讯作者：
KIRK, MM
中科院分区：
文献类型：
--
作者：
KIRK, DL;KIRK, MM
莱茵哈迪氏弧菌具有高亲和力、高特异性的载体，参与外源精氨酸的吸收。载体介导的其他氨基酸的吸收不能被检测到，即使在以氨基酸为氮源或缺乏氮的培养中也是如此。这一事实可能导致分离出对精氨酸以外的氨基酸具有营养缺陷性的菌株；传统的选择介质可能不能提供足够数量的氨基酸来允许营养缺陷型细菌的生长。尿素载体也存在于莱茵梭菌中，但根据动力学性质和对一系列结构类似物的敏感性很容易与精氨酸载体区分开来。氨似乎在调节(抑制)精氨酸摄取系统的活性方面起着主要作用。尿素吸收系统的活性在N饥饿的培养中升高，在尿素或精氨酸存在时甚至进一步升高。在半同步培养中观察到的两种摄取系统的广泛、独立的波动表明，两者都受到一系列复杂的内源和外源因素的调节。
C. reinhardtii possesses a high affinity, highly specific carrier involved in uptake of exogenous arginine. Carrier-mediated uptake of other amino acids cannot be detected, even in cultures maintained on amino acids as a N source or starved for N. This fact may contribute to the difficulty of isolating strains auxotrophic for amino acids other than arginine; conventional selection media may not supply adequate quantities of amino acids to permit growth of auxotrophs. A urea carrier is also present in C. reinhardtii but is readily distinguished from the arginine carrier on the basis of kinetic properties and sensitivity to a range of structural analogs. Ammonia appears to play a major role in regulating (depressing) activity of the arginine uptake system. Activity of the urea uptake system is elevated in N-starved cultures and elevated even further in the presence of urea or arginine. Extensive, independent fluctuations in the 2 uptake systems observed in semisynchronous cultures suggest that both are subject to modulation by a complex set of interacting endogenous and exogenous factors.