de Lacroix de Lavalette Agnès, Finazzi Giovanni, Zito Francesca
UMR 7099, CNRS and Université Paris-7, and UMR 7141, CNRS and Université Paris-6, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, France.
Biochemistry. 2008 May 13;47(19):5259-65. doi: 10.1021/bi800179b. Epub 2008 Apr 12.
Cytochromes bc1/b6f complexes catalyze electron transfer from lipid- to water-soluble carriers in both the respiratory and photosynthetic processes. They contain several common redox cofactors, while a chlorophyll a molecule, the function of which is still enigmatic, is only present in b b6f-type complexes. In this work, we describe a mutagenesis approach aimed at characterizing the role of this pigment. Mutants of the binding pocket were constructed to obtain cytochrome (cyt) b6f f complexes altered in chlorophyll position and/or stability. On the basis of a combined biochemical and functional analysis, we conclude that the chlorophyll plays a major structural role in the complex. Moreover, the chlorophyll and its binding pocket may also be implicated in the regulation of photosynthetic state transitions, a function that is specific to cyt b6f complexes.
细胞色素bc1/b6f复合物在呼吸作用和光合作用过程中催化电子从脂溶性载体转移到水溶性载体。它们含有几种常见的氧化还原辅因子，而一个功能仍不明的叶绿素a分子仅存在于b6f型复合物中。在这项工作中，我们描述了一种诱变方法，旨在表征这种色素的作用。构建了结合口袋的突变体，以获得叶绿素位置和/或稳定性发生改变的细胞色素（cyt）b6f复合物。基于生化和功能的综合分析，我们得出结论，叶绿素在复合物中起主要结构作用。此外，叶绿素及其结合口袋也可能参与光合状态转换的调节，这是cyt b6f复合物特有的功能。
