美国哈佛大学Nicholas W. Bellono等研究人员合作揭示章鱼感觉受体演化的结构基础。这一研究成果于2023年4月12日在线发表在国际学术期刊《自然》上。

研究人员利用章鱼的化学触觉受体（CR）来探测感觉受体演化的结构基础。研究人员展示了章鱼CR的冷冻电镜结构，并将其与烟碱受体进行比较，以确定使环境感觉与神经传导的特征。演化、结构和生物物理分析表明，参与阳离子渗透和信号转导的通道结构是保守的。相比之下，正构配体结合部位受到多样化的选择，从而介导了对新分子的检测。

冷冻电镜结构中的偶然发现显示，章鱼CR配体结合口袋是非常疏水性的，使其能够感觉到油腻的化合物，而不是由典型神经递质受体检测的小极性分子。这些发现为理解原子层面的演化适应性和新生物体行为的出现之间的联系提供了一个结构框架。

据悉，CR是头足类动物特有的创新，使章鱼能够通过“触摸的味道”来探索海底。CR从尼古丁乙酰胆碱受体中分化出来，以介导不溶性分子的接触性化学感知，这些分子在海洋环境中不容易扩散。

附：英文原文

Title: Structural basis of sensory receptor evolution in octopus

Author: Allard, Corey A. H., Kang, Guipeun, Kim, Jeong Joo, Valencia-Montoya, Wendy A., Hibbs, Ryan E., Bellono, Nicholas W.

Issue&Volume: 2023-04-12

Abstract: Chemotactile receptors (CRs) are a cephalopod-specific innovation that allow octopuses to explore the seafloor via ‘taste by touch’1. CRs diverged from nicotinic acetylcholine receptors to mediate contact-dependent chemosensation of insoluble molecules that do not readily diffuse in marine environments. Here we exploit octopus CRs to probe the structural basis of sensory receptor evolution. We present the cryo-electron microscopy structure of an octopus CR and compare it with nicotinic receptors to determine features that enable environmental sensation versus neurotransmission. Evolutionary, structural and biophysical analyses show that the channel architecture involved in cation permeation and signal transduction is conserved. By contrast, the orthosteric ligand-binding site is subject to diversifying selection, thereby mediating the detection of new molecules. Serendipitous findings in the cryo-electron microscopy structure reveal that the octopus CR ligand-binding pocket is exceptionally hydrophobic, enabling sensation of greasy compounds versus the small polar molecules detected by canonical neurotransmitter receptors. These discoveries provide a structural framework for understanding connections between evolutionary adaptations at the atomic level and the emergence of new organismal behaviour.

DOI: 10.1038/s41586-023-05822-1

Source: https://www.nature.com/articles/s41586-023-05822-1