Redox and light regulation of gene expression in photosynthetic prokaryotes
Redox and light regulation of gene expression in photosynthetic prokaryotes
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DOI：
10.1098/rstb.2002.1189
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发表时间：
2003-01-29
影响因子：
6.3
通讯作者：
Masuda, S
中科院分区：
文献类型：
--
作者：
Bauer, C;Elsen, S;Masuda, S
所有光合生物控制光合作用基因的表达，以响应光强度的变化以及细胞氧化还原电位的变化。植物中的光调节涉及一组定义明确的吸收红光和蓝光的光感受器，称为光敏色素和隐花色素。较少了解的是控制植物光系统合成的因素，以响应细胞氧化还原的变化。在各种各样的光合细菌中，最好理解的调节系统是由光合细菌荚膜红细菌合成的那些。该物种使用全局双组分信号转导级联，RegB和RegA，厌氧去抑制厌氧基因表达。在还原条件下，RegB上的磷酸盐转移到RegA，然后激活参与光合作用，固氮，碳固定，呼吸和电子传递的基因。在氧气存在的情况下，有第二个调节因子称为CrtJ，它负责抑制光合作用基因的表达。CrtJ通过在氧化而非还原生长条件下形成分子内二硫键来响应氧化还原。二硫键的存在刺激阻遏物的DNA结合活性。还有一种黄素蛋白，在相关细菌物种球形红细菌（Rhodobacter sphaeroides）中作为CrtJ的蓝光吸收抗阻遏物发挥作用，称为AppA。AppA表现出一种新的长寿命的光循环，这是由黄素的蓝光吸收引发的。一旦兴奋，AppA结合CrtJ，从而抑制CrtJ的阻遏物活性。将讨论这种光循环的各种机制方面。
All photosynthetic organisms control expression of photosynthesis genes in response to alterations in light intensity as well as to changes in cellular redox potential. Light regulation in plants involves a well-defined set of red- and blue-light absorbing photoreceptors called phytochrome and cryptochrome. Less understood are the factors that control synthesis of the plant photosystem in response to changes in cellular redox. Among a diverse set of photosynthetic bacteria the best understood regulatory systems are those synthesized by the photosynthetic bacterium Rhodobacter capsulatus. This species uses the global two-component signal transduction cascade, RegB and RegA, to anaerobically de-repress anaerobic gene expression. Under reducing conditions, the phosphate on RegB is transferred to RegA, which then activates genes involved in photosynthesis, nitrogen fixation, carbon fixation, respiration and electron transport. In the presence of oxygen, there is a second regulator known as CrtJ, which is responsible for repressing photosynthesis gene expression. CrtJ responds to redox by forming an intramolecular disulphide bond under oxidizing, but not reducing, growth conditions. The presence, of the disulphide bond stimulates DNA binding activity of the repressor. There is also a flavoprotein that functions as a blue-light absorbing anti-repressor of CrtJ in the related bacterial species Rhodobacter sphaeroides called AppA. AppA exhibits a novel long-lived photocycle that is initiated by blue-light absorption by the flavin. Once excited, AppA binds to CrtJ thereby inhibiting the repressor activity of CrtJ. Various mechanistic aspects of this photocycle will be discussed.