López-Igual Rocío, Wilson Adjélé, Leverenz Ryan L, Melnicki Matthew R, Bourcier de Carbon Céline, Sutter Markus, Turmo Aiko, Perreau François, Kerfeld Cheryl A, Kirilovsky Diana
Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France (R.L.-I., A.W., C.B.d.C., D.K.);Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, France (R.L.-I., A.W., C.B.d.C., D.K.);MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., M.S., A.T., C.A.K.);Department of Plant and Microbial Biology, University of California, Berkeley, California 94720 (M.R.M., C.A.K.);Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (M.R.M., M.S., C.A.K.); andINRA, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, F-78026 Versailles, France (F.P.).
Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif sur Yvette, France (R.L.-I., A.W., C.B.d.C., D.K.);Institut de Biologie et Technologies de Saclay (iBiTec-S), Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette, France (R.L.-I., A.W., C.B.d.C., D.K.);MSU-DOE Plant Research Laboratory and Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., M.S., A.T., C.A.K.);Department of Plant and Microbial Biology, University of California, Berkeley, California 94720 (M.R.M., C.A.K.);Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (M.R.M., M.S., C.A.K.); andINRA, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, F-78026 Versailles, France (F.P.)
Plant Physiol. 2016 Jul;171(3):1852-66. doi: 10.1104/pp.16.00502. Epub 2016 May 13.
The photoactive Orange Carotenoid Protein (OCP) is involved in cyanobacterial photoprotection. Its N-terminal domain (NTD) is responsible for interaction with the antenna and induction of excitation energy quenching, while the C-terminal domain is the regulatory domain that senses light and induces photoactivation. In most nitrogen-fixing cyanobacterial strains, there are one to four paralogous genes coding for homologs to the NTD of the OCP. The functions of these proteins are unknown. Here, we study the expression, localization, and function of these genes in Anabaena sp. PCC 7120. We show that the four genes present in the genome are expressed in both vegetative cells and heterocysts but do not seem to have an essential role in heterocyst formation. This study establishes that all four Anabaena NTD-like proteins can bind a carotenoid and the different paralogs have distinct functions. Surprisingly, only one paralog (All4941) was able to interact with the antenna and to induce permanent thermal energy dissipation. Two of the other Anabaena paralogs (All3221 and Alr4783) were shown to be very good singlet oxygen quenchers. The fourth paralog (All1123) does not seem to be involved in photoprotection. Structural homology modeling allowed us to propose specific features responsible for the different functions of these soluble carotenoid-binding proteins.
光活性橙色类胡萝卜素蛋白（OCP）参与蓝细菌的光保护作用。其N端结构域（NTD）负责与天线相互作用并诱导激发能猝灭，而C端结构域是感应光并诱导光激活的调节结构域。在大多数固氮蓝细菌菌株中，有一到四个编码OCP的NTD同源物的旁系同源基因。这些蛋白质的功能尚不清楚。在这里，我们研究了这些基因在鱼腥藻PCC 7120中的表达、定位和功能。我们表明，基因组中存在的四个基因在营养细胞和异形胞中均有表达，但似乎在异形胞形成中没有重要作用。这项研究确定，所有四种鱼腥藻NTD样蛋白都能结合类胡萝卜素，并且不同的旁系同源物具有不同的功能。令人惊讶的是，只有一个旁系同源物（All4941）能够与天线相互作用并诱导永久性热能耗散。其他两个鱼腥藻旁系同源物（All3221和Alr4783）被证明是非常好的单线态氧猝灭剂。第四个旁系同源物（All1123）似乎不参与光保护作用。结构同源性建模使我们能够提出导致这些可溶性类胡萝卜素结合蛋白具有不同功能的特定特征。
