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首页> 外文期刊>Journal of Molecular Biology >The solution structure of Rhodobacter sphaeroides LH1beta reveals two helical domains separated by a more flexible region: structural consequences for the LH1 complex.
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The solution structure of Rhodobacter sphaeroides LH1beta reveals two helical domains separated by a more flexible region: structural consequences for the LH1 complex.

机译：球形球形红细菌LH1beta的溶液结构揭示了两个螺旋结构域，由一个更灵活的区域隔开：LH1复合物的结构后果。

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摘要

Here, the solution structure of the Rhodobacter sphaeroides core light-harvesting complex beta polypeptide solubilised in chloroform:methanol is presented. The structure, determined by homonuclear NMR spectroscopy and distance geometry, comprises two alpha helical regions (residue -34 to -15 and -11 to +6, using the numbering system in which the conserved histidine residue is numbered zero) joined by a more flexible four amino acid residue linker. The C-terminal helix forms the membrane spanning region in the intact LH1 complex, whilst the N-terminal helix must lie in the lipid head groups or in the cytoplasm, and form the basis of interaction with the alpha polypeptide. The structure of a mutant beta polypeptide W(+9)F was also determined. This mutant, which is deficient in a hydrogen bond donor to the bacteriochlorophyll, showed an identical structure to the wild-type, implying that observed differences in interaction with other LH1 polypeptides must arise from cofactor binding. Using these structures we propose a modification to existing models of the intact LH1 complex by replacing the continuous helix of the beta polypeptide with two helices, one of which lies at an acute angle to the membrane plane. We suggest that a key difference between LH1 and LH2 is that the beta subunit is more bent in LH1. This modification puts the N terminus of LH1beta close to the reaction centre H subunit, and provides a rationale for the different ring sizes of LH1 and LH2 complexes. Copyright 2000 Academic Press.
机译：在这里，提出了球形球形红细菌核心光收集复杂β多肽溶解在氯仿：甲醇中的溶液结构。通过同核NMR光谱学和距离几何学确定的结构包含两个α螺旋区域（残基-34至-15和-11至+6，其中使用保守的组氨酸残基编号为零的编号系统），该区域更灵活四个氨基酸残基接头。 C末端螺旋在完整的LH1复合物中形成跨膜区域，而N末端螺旋必须位于脂质头基或细胞质中，并形成与α多肽相互作用的基础。还确定了突变体β多肽W（+9）F的结构。该突变体缺乏细菌叶绿素的氢键供体，显示出与野生型相同的结构，这表明观察到的与其他LH1多肽相互作用的差异必须由辅因子结合引起。使用这些结构，我们建议通过用两个螺旋取代β多肽的连续螺旋来对完整的LH1复合体的现有模型进行修改，其中两个螺旋与膜平面成锐角。我们建议LH1和LH2之间的主要区别在于β亚基在LH1中更易弯曲。这种修饰使LH1beta的N末端靠近反应中心的H亚基，并为LH1和LH2配合物的不同环大小提供了理论依据。版权所有2000学术出版社。

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