虽然藻类和植物需要大量光进行光合作用，但光照太多也会是有害的，造成严重氧化损伤、甚至细胞死亡。光合作用中光摄取的快速调控，通过“光合系统-II”中叶绿素分子由反馈调控的去激发为光合作用提供了一个安全阀。但是，人们对真核藻类中的这一防卫体系的机制却知之甚少。
现在，用缺少为LHCSR编码的三个基因中之两个的单细胞藻类“莱茵衣藻”的突变体所做的一项研究表明，这种蛋白（光摄取复合物超级家族中一个古老成员，在维管植物中没有）是在一个光照条件存在波动的环境中生存所必需的。这意味着，植物和藻类利用不同蛋白来保护光合作用器官不受损伤。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 462, 518-521 (26 November 2009) | doi:10.1038/nature08587
An ancient light-harvesting protein is critical for the regulation of algal photosynthesis
Graham Peers1,5, Thuy B. Truong1,2,6, Elisabeth Ostendorf3,6, Andreas Busch3, Dafna Elrad4, Arthur R. Grossman4, Michael Hippler3 & Krishna K. Niyogi1,2
1 Department of Plant and Microbial Biology, University of California, Berkeley, California 94720-3102, USA
2 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
3 Institute of Plant Biochemistry and Biotechnology, University of Münster, 48143 Münster, Germany
4 Department of Plant Biology, Carnegie Institution, Stanford, California 94305, USA
5 Present address: Synthetic Genomics, Inc., 11149 North Torrey Pines Road, Suite 100, La Jolla, California 92037, USA.
6 These authors contributed equally to this work.
Correspondence to: Michael Hippler3Krishna K. Niyogi1,2 Correspondence and requests for materials should be addressed to K.K.N.or M.H.
Light is necessary for photosynthesis, but its absorption by pigment molecules such as chlorophyll can cause severe oxidative damage and result in cell death. The excess absorption of light energy by photosynthetic pigments has led to the evolution of protective mechanisms that operate on the timescale of seconds to minutes and involve feedback-regulated de-excitation of chlorophyll molecules in photosystem II (qE). Despite the significant contribution of eukaryotic algae to global primary production1, little is known about their qE mechanism, in contrast to that in flowering plants2, 3. Here we show that a qE-deficient mutant of the unicellular green alga Chlamydomonas reinhardtii, npq4, lacks two of the three genes encoding LHCSR (formerly called LI818). This protein is an ancient member of the light-harvesting complex superfamily, and orthologues are found throughout photosynthetic eukaryote taxa4, except in red algae and vascular plants. The qE capacity of Chlamydomonas is dependent on environmental conditions and is inducible by growth under high light conditions. We show that the fitness of the npq4 mutant in a shifting light environment is reduced compared to wild-type cells, demonstrating that LHCSR is required for survival in a dynamic light environment. Thus, these data indicate that plants and algae use different proteins to dissipate harmful excess light energy and protect the photosynthetic apparatus from damage.
