School of Chemistry and Biochemistry, Clark University, Worcester, Massachusetts.
Biophys J. 2013 Sep 17;105(6):1346-56. doi: 10.1016/j.bpj.2013.07.027.
Green photosynthetic bacteria adjust the structure and functionality of the chlorosome-the light-absorbing antenna complex-in response to environmental stress factors. The chlorosome is a natural self-assembled aggregate of bacteriochlorophyll (BChl) molecules. In this study, we report the regulation of the biogenesis of the Chlorobaculum tepidum chlorosome by carbon assimilation in conjunction with temperature changes. Our studies indicate that the carbon source and thermal stress culture of C. tepidum grows slower and incorporates fewer BChl c in the chlorosome. Compared with the chlorosome from other cultural conditions we investigated, the chlorosome from the carbon source and thermal stress culture displays (a) smaller cross-sectional radius and overall size, (b) simplified BChl c homologs with smaller side chains, (c) blue-shifted Qy absorption maxima, and (d) a sigmoid-shaped circular dichroism spectra. Using a theoretical model, we analyze how the observed spectral modifications can be associated with structural changes of BChl aggregates inside the chlorosome. Our report suggests a mechanism of metabolic regulation for chlorosome biogenesis.
绿硫细菌会根据环境压力因素来调整类囊体（光吸收天线复合物）的结构和功能。类囊体是细菌叶绿素（BChl）分子的自然自组装聚集体。在这项研究中，我们报告了与温度变化相结合的碳同化对嗜热绿硫菌类囊体生物发生的调节。我们的研究表明，碳源和热应激培养的嗜热绿硫菌生长速度较慢，并且在类囊体中掺入较少的 BChl c。与我们研究的其他培养条件的类囊体相比，来自碳源和热应激培养的类囊体显示出：(a) 更小的横截面半径和整体尺寸；(b) 具有较小侧链的简化 BChl c 同系物；(c) Qy 吸收最大值蓝移；和 (d) 呈钟形的圆二色性光谱。我们使用理论模型分析了观察到的光谱修饰如何与类囊体内部 BChl 聚集体的结构变化相关联。我们的报告表明了一种代谢调节机制，用于类囊体生物发生。
