Partial symmetrization of the photosynthetic reaction center.
Partial symmetrization of the photosynthetic reaction center.
复制标题
光合反应中心的部分对称化。
DOI：
10.1126/science.2192455
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Youvan,DC
中科院分区：
文献类型：
--
作者：
Robles,SJ;Breton,J;Youvan,DC
细菌光合反应中心（RC）是一种有色素的内在膜蛋白，它执行光合作用的主要电荷分离事件，从而将光能转化为化学能。 RC 色素主要由两个同源肽（L 和 M 亚基）结合，每个亚基包含五个跨膜螺旋。这些α螺旋和色素以近似C2对称性排列，并形成两种可能的电子转移路径。实际上仅使用这些途径之一。为了鉴定导致两个分支之间功能差异的非同源残基，与色素广泛相互作用的同源螺旋区域被遗传对称化（即交换）。例如，用 L 亚基的同源螺旋替换 M 亚基中的第四个跨膜螺旋（D 螺旋），会产生缺乏关键光活性色素的光合无活性 RC。已经分离出光合回复体，其中单个氨基酸取代（基因内抑制子）补偿了这种部分对称化。
The bacterial photosynthetic reaction center (RC) is a pigmented intrinsic membrane protein that performs the primary charge separation event of photosynthesis, thereby converting light to chemical energy. The RC pigments are bound primarily by two homologous peptides, the L and M subunits, each containing five transmembrane helices. These α helices and pigments are arranged in an approximate C2symmetry and form two possible electron transfer pathways. Only one of these pathways is actually used. In an attempt to identify nonhomologous residues that are responsible for functional differences between the two branches, homologous helical regions that interact extensively with the pigments were genetically symmetrized (that is, exchanged). For example, replacement of the fourth transmembrane helix (D helix) in the M subunit with the homologous helix from the L subunit yields photosynthetically inactive RCs lacking a critical photoactive pigment. Photosynthetic revertants have been isolated in which single amino acid substitutions (intragenic suppressors) compensate for this partial symmetrization.