Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum
Gene sequencing and characterization of the light-harvesting complex 2 from thermophilic purple sulfur bacterium Thermochromatium tepidum
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DOI：
10.1007/s11120-011-9658-9
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发表时间：
2012-03-01
影响因子：
3.7
通讯作者：
Wang, Zheng-Yu
中科院分区：
文献类型：
--
作者：
Sekine, Fumie;Horiguchi, Kentaro;Wang, Zheng-Yu
在这项研究中，基因序列编码的捕光（LH）2多肽从嗜热紫色硫细菌Thermochromatium tepidum的报道和表征的LH 2复杂的描述。已经鉴定了三组pucBA基因，并通过电泳和反相色谱分析了基因产物。结果表明，所有的基因表达，但表达的分布是不均匀的。基因产物经历翻译后修饰，其中两个β-多肽似乎是N-末端甲基化的。提纯的LH_2配合物在十二烷基β-麦芽吡喃糖苷溶液中的吸收光谱在800和854 nm处出现Q（y）跃迁，圆二色光谱显示出“茂茂”的特征。LH 2在不同光照条件下培养，其光谱无明显变化。在十二烷基二甲基胺N-氧化物（LDAO）的溶液中，吸收光谱的显着变化进行了观察。随着LDAO浓度的增加，B850峰降低并蓝移，而B800强度增加而峰位不变。光谱的变化可以部分或几乎完全逆转通过添加金属离子，和二价阳离子似乎更有效。结果表明，LH 2、洗涤剂分子和金属离子之间可能存在离子相互作用。洗涤剂和阳离子引起的光谱变化可能涉及的机制进行了讨论。
In this study, gene sequences coding for the light-harvesting (LH) 2 polypeptides from a thermophilic purple sulfur bacterium Thermochromatium tepidum are reported and characterization of the LH2 complex is described. Three sets of pucBA genes have been identified, and the gene products have been analyzed by electrophoresis and reversed-phase chromatography. The result shows that all of the genes are expressed but the distribution of the expression is not uniform. The gene products undergo post-translational modification, where two of the beta-polypeptides appear to be N-terminally methylated. Absorption spectrum of the purified LH2 complex exhibits Q(y) transitions at 800 and 854 nm in dodecyl beta-maltopyranoside solution, and the circular dichroism spectrum shows a "molischianum''-like characteristic. No spectral change was observed for the LH2 when the bacterium was cultured under different conditions of light intensity. In lauryl dimethylamine N-oxide (LDAO) solution, significant changes in the absorption spectrum were observed. The B850 peak decreased and blue-shifted with increasing the LDAO concentration, whereas the B800 intensity increased without change in the peak position. The spectral changes can be partially or almost completely reversed by addition of metal ions, and the divalent cations seem to be more effective. The results indicate that ionic interactions may exist between LH2, detergent molecules and metal ions. Possible mechanisms involved in the detergent-and cation-induced spectral changes are discussed.