CpeY is a phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I α-subunit in marine Synechococcus
CpeY is a phycoerythrobilin lyase for cysteine 82 of the phycoerythrin I α-subunit in marine Synechococcus
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DOI：
10.1016/j.bbabio.2020.148215
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发表时间：
2020-08-01
影响因子：
4.3
通讯作者：
Schluchter, Wendy M.
中科院分区：
文献类型：
--
作者：
Carrigee, Lyndsay A.;Mahmoud, Rania M.;Schluchter, Wendy M.
海洋聚藻球菌之所以广泛存在，部分原因是它们利用其复杂的天线或藻胆异构体（由多种藻胆蛋白和胆囊蛋白发色团组成）有效地收集可用光。据预测，超过40%的聚球菌菌株会进行一种颜色驯化，这种驯化会改变两种发色团的比例，即吸收绿光的藻红蛋白和吸收蓝光的藻红蛋白，以优化藻绿酶体中藻红蛋白的光捕获。裂解酶是一种催化胆管蛋白上特定半胱氨酸残基向胆管蛋白上添加胆管蛋白发色团的酶，并参与颜色驯化。CpeY是模式菌株聚球菌RS9916中的一种候选裂解酶，在重组蛋白表达系统中，在存在或不存在伴侣样蛋白CpeZ的情况下，仅将藻红蛋白I （CpeA）的a亚基的半胱氨酸82中添加藻红蛋白。这些研究表明，重组CpeY将藻红蛋白附着在高达72%的CpeA上，使其成为迄今为止表征的最有效的藻红蛋白裂解酶之一。cpeY（-）突变体的藻胆异构体在所有光照条件下都显示出接近天然的胆红素组成，除了在CpeA半胱氨酸82中，藻红胆红素被藻红胆红素轻微取代。这表明CpeY不参与任何颜色驯化驱动的发色团变化，并表明CpeY（-）突变体中附着在CpeA半胱氨酸82上的发色团是由另一种植物红蛋白裂解酶连接的。虽然CpeY的缺失对体内天然藻胆小体的组装没有很大的抑制作用，但高活性的重组CpeY可以用来产生大量的荧光CpeA，用于生物技术用途。
Marine Synechococcus are widespread in part because they are efficient at harvesting available light using their complex antenna, or phycobilisome, composed of multiple phycobiliproteins and bilin chromophores. Over 40% of Synechococcus strains are predicted to perform a type of chromatic acclimation that alters the ratio of two chromophores, green-light-absorbing phycoerythrobilin and blue-light-absorbing phycourobilin, to optimize light capture by phycoerythrin in the phycobilisome. Lyases are enzymes which catalyze the addition of bilin chromophores to specific cysteine residues on phycobiliproteins and are involved in chromatic acclimation. CpeY, a candidate lyase in the model strain Synechococcus sp. RS9916, added phycoerythrobilin to cysteine 82 of only the a subunit of phycoerythrin I (CpeA) in the presence or absence of the chaperone-like protein CpeZ in a recombinant protein expression system. These studies demonstrated that recombinant CpeY attaches phycoerythrobilin to as much as 72% of CpeA, making it one of the most efficient phycoerythrin lyases characterized to date. Phycobilisomes from a cpeY(-) mutant showed a near native bilin composition in all light conditions except for a slight replacement of phycoerythrobilin by phycourobilin at CpeA cysteine 82. This demonstrates that CpeY is not involved in any chromatic acclimation-driven chromophore changes and suggests that the chromophore attached at cysteine 82 of CpeA in the cpeY(-) mutant is ligated by an alternative phycoerythrobilin lyase. Although loss of CpeY does not greatly inhibit native phycobilisome assembly in vivo, the highly active recombinant CpeY can be used to generate large amounts of fluorescent CpeA for biotechnological uses.