Vaknin Ady, Berg Howard C
The Racah Institute of Physics, The Hebrew University, Jerusalem 91904, Israel.
J Mol Biol. 2008 Oct 10;382(3):573-7. doi: 10.1016/j.jmb.2008.07.026. Epub 2008 Jul 16.
Bacterial chemoreceptors form mixed trimers of homodimers that cluster further in the presence of other cytoplasmic components. The physical proximity between receptors is thought to promote conformational coupling that enhances sensitivity, dynamic range, and collaboration between receptors of different types. We investigated conformational coupling between neighboring dimers by co-expressing two types of receptors, only one of which was labeled with yellow fluorescent protein. The two types of receptors were stimulated independently, and changes in the relative orientation of the labeled receptors were followed by fluorescence anisotropy. Possible coupling via cytoplasmic components of the taxis system was avoided by working with strains lacking those components. We find that binding of ligand to one type of receptor affects the conformation of the other type of receptor but not in the same way as binding of ligand to that receptor directly does. Thus, different receptors are coupled but not as simply as previously thought.
细菌化学感受器形成同型二聚体的混合三聚体，在其他细胞质成分存在的情况下会进一步聚集。感受器之间的物理接近被认为会促进构象偶联，从而提高敏感性、动态范围以及不同类型感受器之间的协作。我们通过共表达两种类型的感受器来研究相邻二聚体之间的构象偶联，其中只有一种用黄色荧光蛋白标记。两种类型的感受器被独立刺激，标记感受器相对取向的变化通过荧光各向异性来跟踪。通过使用缺乏那些成分的菌株，避免了通过趋化系统的细胞质成分进行可能的偶联。我们发现配体与一种类型感受器的结合会影响另一种类型感受器的构象，但方式与配体直接与该感受器结合不同。因此，不同的感受器是偶联的，但不像之前认为的那么简单。
