Purification and Characterization of the Polypeptides of Core Light-Harvesting Complexes from Purple Sulfur Bacteria
Purification and Characterization of the Polypeptides of Core Light-Harvesting Complexes from Purple Sulfur Bacteria
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DOI：
10.1023/b:pres.0000004328.11219.79
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发表时间：
2004
影响因子：
3.7
通讯作者：
Zheng‐Yu Wang;M. Shimonaga;Hiroaki Suzuki;Masayuki Kobayashi;T. Nozawa
中科院分区：
文献类型：
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作者：
Zheng‐Yu Wang;M. Shimonaga;Hiroaki Suzuki;Masayuki Kobayashi;T. Nozawa
尽管许多紫色非硫细菌的核心捕光复合体(LH1)的多肽已经被很好地表征，但关于紫色硫光合生物的LH1多肽的信息很少。本文报道了从两株紫色硫磺细菌Thermochromatium(Tch.)tepidumandAllochromatium(Ach.)vinosum.中分离和鉴定LH1多肽的结果。以反应中心(RC)结合的形式提取和纯化了天然的LH1复合体，Tch.tepidum和Ach.vinosum的Qy吸收分别为914 nm和889 nm。反相高效液相色谱鉴定了天冬虫夏草LH1蛋白多肽中的三个组分。发现β-多肽在N-末端发生甲基化，鉴定出两个α-多肽，其中一个在N-末端蛋氨酸残基被甲酰基修饰。确定了两个α-和两个β-多肽，并精确测定了它们的一级结构。用细菌叶绿体和分离的α-和β-多肽检测同源和杂交重组能力。烟草β-多肽不仅能与烟草α-多肽形成统一的结构亚基，而且能与非硫红色红螺菌的α-多肽形成统一的结构亚基。在重组实验中，单独的α多肽或单独的β多肽似乎只导致不完整的亚基。
Although the polypeptides of core light-harvesting complexes (LH1) from many purple nonsulfur bacteria have been well characterized, little information is available on the polypeptides of LH1 from purple sulfur photosynthetic organisms. We present here the results of isolation and characterization of LH1 polypeptides from two purple sulfur bacteria,Thermochromatium(Tch.)tepidumandAllochromatium(Ach.)vinosum. Native LH1 complexes were extracted and purified in a reaction center (RC)-associated form with the Qy absorption at 914 nm and 889 nm forTch.tepidum and Ach.vinosum, respectively. Three components were confirmed from reverse-phase HPLC for the LH1 apopolypeptides ofTch.tepidum. The β-polypeptide was found to be methylated at N-terminus, and two α-polypeptides were identified with one of them being modified by a formyl group at the N-terminal methionine residue. Two α- and two β-polypeptides were confirmed for the LH1 complex ofAch.vinosum, and their primary structures were precisely determined. Homologous and hybrid reconstitution abilities were examined using bacteriochlorophyllaand separated α- and β-polypeptides. The β-polypeptide fromTch.tepidumwas capable of forming uniform structural subunit not only with the α-polypeptide ofTch.tepidumbut also with the α-polypeptide from a nonsulfur bacteriumRhodospirillum rubrum. The α-polypeptide alone or β-polypeptide alone appeared only to result in incomplete subunits in the reconstitution experiments.