Effects of Carotenoid Inhibition on the Photosynthetic RC–LH1 Complex in Purple Sulphur Bacterium Thiorhodospira sibirica
Effects of Carotenoid Inhibition on the Photosynthetic RC–LH1 Complex in Purple Sulphur Bacterium Thiorhodospira sibirica
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DOI：
10.1007/s11120-005-4473-9
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发表时间：
2005-11
影响因子：
3.7
通讯作者：
A. Moskalenko;Z. Makhneva;L. Fiedor;H. Scheer
中科院分区：
文献类型：
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作者：
A. Moskalenko;Z. Makhneva;L. Fiedor;H. Scheer
使用制备型凝胶电泳从紫色细菌西伯利亚硫红螺菌的光合膜中分离出核心复合物（LH1-RC），该细菌在不存在或存在类胡萝卜素生物合成抑制剂二苯胺的情况下生长。二苯胺对类胡萝卜素的生物合成产生定量和定性的影响：通过HPLC和吸收光谱分析，抑制后核心复合物中类胡萝卜素的水平仅达到正常含量的10%。正常生长的细菌生物合成螺菌黄质、视紫红质、脱水红素和番茄红素，而在抑制后，复合物中仅发现神经孢子烯、β-胡萝卜素及其衍生物。没有伴随大量无色类胡萝卜素前体的积累。有趣的是，从类胡萝卜素抑制的细胞中分离出的核心光捕获复合物的主要吸收带显示红移至 889 nm，而不是在许多类胡萝卜素缺乏的紫色光合细菌物种中观察到的蓝移。分离的核心复合物对正辛基-β-D-吡喃葡萄糖苷的稳定性显然取决于类胡萝卜素的存在。由去污剂处理产生的子复合物通过与原位吸收光谱相结合的非变性凝胶电泳进行表征。具有天然类胡萝卜素补体的核心复合物解离成三个子复合物：(a) 部分耗尽类胡萝卜素的 LH1 复合物，在 NIR 区域具有不寻常的光谱（λmax= 791、818、847 和 875 nm），(b) 与 LH1 片段相关的反应中心，(c) 少量的无类胡萝卜素 B820 子复合物。来自类胡萝卜素缺陷细菌的核心复合物稳定性要差得多，并且仅产生两个子复合物（b）和（c）。我们得出的结论是，类胡萝卜素对核心复合物与洗涤剂的稳定性和相互作用起着至关重要的作用。
Core complexes (LH1–RC) were isolated using preparative gel electrophoresis from photosynthetic membranes of the purple bacterium,Thiorhodospira sibirica, grown in the absence or presence of the carotenoid biosynthesis inhibitor, diphenylamine. The biosynthesis of carotenoids is affected by diphenylamine both quantitavely and qualitatively: after inhibition, the level of carotenoids in core complexes reaches only 10% of the normal content, as analyzed by HPLC and absorption spectroscopy. The normally grown bacterium biosynthesizes spirilloxanthin, rhodopin, anhydrorhodovibrin and lycopene, whereas after inhibition only neurosporene, ζ-carotene and their derivatives are found in the complexes. There is no concomitant accumulation of appreciable amounts of colorless carotenoid precursors. Interestingly, the main absorption band of the core light harvesting complex isolated from carotenoid-inhibited cells, shows a red shift to 889 nm, instead of a blue shift observed in many carotenoid-deficient species of purple photosynthetic bacteria.The stability of isolated core complexes againstn-octyl-β-D-glucopyranoside clearly depends on the presence of carotenoids. Subcomplexes resulting from the detergent treatment, were characterized by non-denaturating gel electrophoresis combined within situabsorption spectroscopy. Core complexes with the native carotenoid complement dissociate into three subcomplexes: (a) LH1 complexes partially depleted of carotenoids, with an unusual spectrum in the NIR region (λmax= 791, 818, 847 and 875 nm), (b) reaction centers associated with fragments of LH1, (c) small amounts of a carotenoidless B820 subcomplex. The core complex from the carotenoid-deficient bacterium is much less stable and yields only the two sub-complexes (b) and (c). We conclude that carotenoids contribute critically to stability and interactions of the core complexes with detergents.