Lycopene-Family Carotenoids Confer Thermostability on Photocomplexes from a New Thermophilic Purple Bacterium
Lycopene-Family Carotenoids Confer Thermostability on Photocomplexes from a New Thermophilic Purple Bacterium
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番茄红素家族类胡萝卜素赋予新型嗜热紫色细菌的光复合物热稳定性
DOI：
10.1021/acs.biochem.0c00192
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发表时间：
2020
期刊：
影响因子：
2.9
通讯作者：
Kimura Yukihiro
中科院分区：
文献类型：
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作者：
Seto Ryuta;Takaichi Shinichi;Kurihara Toshiyuki;Kishi Rikako;Honda Mai;Takenaka Shinji;Tsukatani Yusuke;Madigan Michael T.;Wang-Otomo Zheng-Yu;Kimura Yukihiro
暗裂绿球藻是一种新发现的含细菌叶绿素b的紫色嗜热细菌。使用纯化的捕光1反应中心（LH 1-RC）核心复合物从Blc.tepida，我们比较了这些复合物的生化，光谱和热变性特性与其嗜温对应物，Blc。绿色的除了它们的生长温度最适，两个物种之间的显着差异被认为是在其LH 1-RC复合物的类胡萝卜素组合物。热稳定性较好的Blc.tepidacomplex含有较多的共轭长度较长的类胡萝卜素（n> 9），如番茄红素（n= 11），且总类胡萝卜素含量显著高于Blc。viridiscomplex，无论用于生长的光强度如何。LH 1-RC的热稳定性从两个Blc. tepidaandBlc.在二苯胺存在下生长的细胞中，viridis显著降低，二苯胺是一种抑制高度共轭类胡萝卜素形成的化合物。相反，嗜热紫色细菌Thermochromatium tepidum，其中Ca 2+是必不可少的LH 1-RC的热稳定性，Ca 2+既不存在，也没有任何影响theBlc. tepidaLH 1-RC的热稳定性。这些结果表明，类胡萝卜素与延长共轭增强与蛋白质的疏水相互作用的机制。tepidaLH 1-RC，从而使复合物能够耐受热变性。这一结论是支持的结构模型的BLC。tepidaLH 1-RC，并且是与基于类胡萝卜素的机制相关联的光复合物热稳定性的第一个实例。
Blastochloris tepidais a newly described thermophilic purple bacterium containing bacteriochlorophyllb. Using purified light-harvesting 1 reaction center (LH1-RC) core complexes fromBlc.tepida, we compared the biochemical, spectroscopic, and thermal denaturation properties of these complexes with those of its mesophilic counterpart,Blc. viridis. Besides their growth temperature optima, a striking difference between the two species was seen in the carotenoid composition of their LH1-RC complexes. The more thermostableBlc.tepidacomplex contained more carotenoids with longer conjugation lengths (n> 9), such as lycopenes (n= 11), and had a total carotenoid content significantly higher than that of theBlc. viridiscomplex, irrespective of the light intensity used for growth. The thermostability of LH1-RCs from bothBlc. tepidaandBlc. viridisdecreased significantly in cells grown in the presence of diphenylamine, a compound that inhibits the formation of highly conjugated carotenoids. In contrast to the thermophilic purple bacteriumThermochromatium tepidum, where Ca2+is essential for LH1-RC thermostability, Ca2+neither was present in nor had any effect on the thermostability of theBlc.tepidaLH1-RC. These results point to a mechanism that carotenoids with elongated conjugations enhance hydrophobic interactions with proteins in theBlc. tepidaLH1-RC, thereby allowing the complexes to withstand thermal denaturation. This conclusion is bolstered by a structural model of theBlc. tepidaLH1-RC and is the first example of photocomplex thermostability being linked to a carotenoid-based mechanism.