Vasil'ev Sergej, Bruce Doug
Department of Biological Sciences, Brock University, St. Catharines, Ontario, L2S 3A1, Canada.
Plant Cell. 2004 Nov;16(11):3059-68. doi: 10.1105/tpc.104.024174. Epub 2004 Oct 14.
The efficiency of oxygenic photosynthesis depends on the presence of core antenna chlorophyll closely associated with the photochemical reaction centers of both photosystem II (PSII) and photosystem I (PSI). Although the number and overall arrangement of these chlorophylls in PSII and PSI differ, structural comparison reveals a cluster of 26 conserved chlorophylls in nearly identical positions and orientations. To explore the role of these conserved chlorophylls within PSII and PSI we studied the influence of their orientation on the efficiency of photochemistry in computer simulations. We found that the native orientations of the conserved chlorophylls were not optimal for light harvesting in either photosystem. However, PSII and PSI each contain two highly orientationally optimized antenna chlorophylls, located close to their respective reaction centers, in positions unique to each photosystem. In both photosystems the orientation of these optimized bridging chlorophylls had a much larger impact on photochemical efficiency than the orientation of any of the conserved chlorophylls. The differential optimization of antenna chlorophyll is discussed in the context of competing selection pressures for the evolution of light harvesting in photosynthesis.
氧光合作用的效率取决于与光系统II(PSII)和光系统I(PSI)的光化学反应中心紧密相关的核心天线叶绿素的存在。尽管PSII和PSI中这些叶绿素的数量和总体排列不同,但结构比较显示在几乎相同的位置和取向上有一组26个保守叶绿素。为了探究这些保守叶绿素在PSII和PSI中的作用,我们在计算机模拟中研究了它们的取向对光化学效率的影响。我们发现,保守叶绿素的天然取向对于任一光系统中的光捕获都不是最佳的。然而,PSII和PSI各自含有两个高度取向优化的天线叶绿素,它们靠近各自的反应中心,位于每个光系统特有的位置。在两个光系统中,这些优化的桥连叶绿素的取向对光化学效率的影响比任何保守叶绿素的取向都要大得多。在光合作用中光捕获进化的竞争选择压力背景下讨论了天线叶绿素的差异优化。