Probing the Spatial Organization of Bacteriochlorophyll c by Solid-State Nuclear Magnetic Resonance

详细信息    查看全文

• 作者：Shih-Chi Luo ; Yadana Khin ; Shing-Jong Huang ; Yanshen Yang ; Tsai-yi Hou ; Yuan-Chung Cheng ; Hao Ming Chen ; Yi-Ying Chin ; Chien-Te Chen ; Hong-Ji Lin ; Joseph Kuo-Hsiang Tang ; Jerry Chun Chung Chan
• 刊名：Biochemistry
• 出版年：2014
• 出版时间：September 2, 2014
• 年：2014
• 卷：53
• 期：34
• 页码：5515-5525
• 全文大小：473K
• ISSN：1520-4995

文摘

Green sulfur bacteria, which live in extremely low-light environments, use chlorosomes to harvest light. A chlorosome is the most efficient, and arguably the simplest, light-harvesting antenna complex, which contains hundreds of thousands of densely packed bacteriochlorophylls (BChls). To harvest light efficiently, BChls in a chlorosome form supramolecular aggregates; thus, it is of great interest to determine the organization of the BChls in a chlorosome. In this study, we conducted a ¹³C solid-state nuclear magnetic resonance and Mg K-edge X-ray absorption analysis of chlorosomes from wild-type Chlorobaculum tepidum. The X-ray absorption results indicated that the coordination number of the Mg in the chlorosome must be >4, providing evidence that electrostatic interactions formed between the Mg of a BChl and the carbonyl group or the hydroxyl group of the neighboring BChl molecule. According to the intermolecular distance constraints obtained on the basis of ¹³C homonuclear dipolar correlation spectroscopy, we determined that the molecular assembly of BChls is dimer-based and that the hydrogen bonds among the BChls are less extensive than commonly presumed because of the twist in the orientation of the BChl dimers. This paper also reports the first ¹³C homonuclear correlation spectrum acquired for carotenoids and lipids鈥攚hich are minor, but crucial, components of chlorosomes鈥攅xtracted from wild-type Cba. tepidum.