Far-red light photoacclimation: Chromophorylation of FR induced α- and β-subunits of allophycocyanin from Chroococcidiopsis thermalis sp. PCC7203.
Far-red light photoacclimation: Chromophorylation of FR induced α- and β-subunits of allophycocyanin from Chroococcidiopsis thermalis sp. PCC7203.
复制标题
DOI：
10.1016/j.bbabio.2016.06.008
复制
发表时间：
2016-09
期刊：
影响因子：
--
通讯作者：
Qianzhao Xu;Jia-Xin Han;Qi-Ying Tang;W. Ding;Dan Miao;M. Zhou;H. Scheer;K. Zhao
中科院分区：
文献类型：
--
作者：
Qianzhao Xu;Jia-Xin Han;Qi-Ying Tang;W. Ding;Dan Miao;M. Zhou;H. Scheer;K. Zhao
蓝藻的光收集复合体，藻胆体，可以在不同的光条件下进行广泛的重塑。对远红光的适应不仅涉及光系统中红移叶绿素的产生，还涉及与藻胆体红移组分相关的核心胆蛋白的额外拷贝（Gan等人，Life 5,4,2015）。我们正在研究热球藻这些驯化的分子基础。PCC7203。在大肠杆菌中表达了5个远红诱导的异藻蓝蛋白亚基（ApcA2、ApcA3、ApcB2、ApcB3和ApcF2），以及s型发色团蛋白裂解酶和情境生成的发色团藻蓝胆素。只有一个亚基ApcF2表现出不寻常的红移（λAmax~ 675 nm, λFmax~ 698 nm）：它与发色团非共价结合，从而保持其完整的共轭长度。这种机制也适用于两种大体积APC诱导亚基的cys变体。所有其他野生型亚基在裂解酶CpcS1的催化下将藻蓝胆素共价结合到常规的Cys-81上。虽然其中3个也与额外的半胱氨酸结合，但它们的吸收和荧光都与传统APC亚基相似（λAmax~ 610 nm, λFmax~ 640 nm）。然而，当远红诱导的大体积APC的不同野生型α-和β-亚基以组合方式组合时，确定了红移复合物的另一个来源。α-亚基PCB-ApcA2和β-亚基PCB-ApcB2一起生成时，形成了强红移配合物（λFmax≤722 nm）。杆菌。这种极端聚集诱导的~ 90 nm的红移与传统APC观察到的~ 30 nm红移相似，但要大得多。
Cyanobacterial light-harvesting complexes, phycobilisomes, can undergo extensive remodeling under varying light conditions. Acclimation to far-red light involves not only generation of red-shifted chlorophylls in the photosystems, but also induction of additional copies of core biliproteins that have been related to red-shifted components of the phycobilisome (Gan et al., Life 5, 4, 2015). We are studying the molecular basis for these acclimations inChroococcidiopsis thermalissp. PCC7203. Five far-red induced allophycocyanin subunits (ApcA2, ApcA3, ApcB2, ApcB3 and ApcF2) were expressed inEscherichia coli, together with S-type chromophore-protein lyases andin situgenerated chromophore, phycocyanobilin. Only one subunit, ApcF2, shows an unusual red-shift (λAmax~ 675 nm, λFmax~ 698 nm): it binds the chromophore non-covalently, thereby preserving its full conjugation length. This mechanism operates also in two Cys-variants of the induced subunits of bulky APC. All other wild-type subunits bind phycocyanobilin covalently to the conventional Cys-81 under catalysis of the lyase, CpcS1. Although three of them also show binding to additional cysteines, all absorb and fluoresce similar to conventional APC subunits (λAmax~ 610 nm, λFmax~ 640 nm). Another origin of red-shifted complexes was identified, however, when different wild-type α- and β-subunits of the far-red induced bulky APC were combined in a combinatorial fashion. Strongly red-shifted complexes (λFmax≤ 722 nm) were formed when the α-subunit, PCB-ApcA2, and the β-subunit, PCB-ApcB2, were generated together inE. coli. This extreme aggregation-induced red-shift of ~ 90 nm of covalently bound chromophores is reminiscent, but much larger, than the ~ 30 nm observed with conventional APC.