荷兰代尔夫特理工大学Arjen J. Jakobi等研究人员合作报道用于浮力控制运动的气囊的冷冻电镜结构。这一研究成果于2023年3月2日发表在国际学术期刊《细胞》上。

研究人员报告了由结构蛋白GvpA制成的气囊壳的3.2埃冷冻电镜结构，该结构蛋白自组装成空心螺旋圆柱体，由锥状尖端关闭。两个螺旋形的半壳通过GvpA单体的特征性排列连接起来，表明了气囊的生物生成机制。GvpA的褶皱具有典型的承力薄壁圆柱体的波纹状壁结构。小孔使气体分子能够在外壳上扩散，而异常疏水性的内表面则有效地排斥水。比较结构分析证实了气囊集合体的演化养护，并证明了GvpC加固外壳的分子特征。这项发现将进一步研究气囊生物学，并促进用于超声成像的气囊的分子工程。

据介绍，气囊是充满气体的纳米舱，使不同种类的细菌和古细菌能够控制其浮力。它们的特性和组装的分子基础仍然不清楚。

附：英文原文

Title: Cryo-EM structure of gas vesicles for buoyancy-controlled motility

Author: Stefan T. Huber, Dion Terwiel, Wiel H. Evers, David Maresca, Arjen J. Jakobi

Issue&Volume: 2023/03/02

Abstract: Gas vesicles are gas-filled nanocompartments that allow a diverse group of bacteria and archaea to control their buoyancy. The molecular basis of their properties and assembly remains unclear. Here, we report the 3.2 cryo-EM structure of the gas vesicle shell made from the structural protein GvpA that self-assembles into hollow helical cylinders closed off by cone-shaped tips. Two helical half shells connect through a characteristic arrangement of GvpA monomers, suggesting a mechanism of gas vesicle biogenesis. The fold of GvpA features a corrugated wall structure typical for force-bearing thin-walled cylinders. Small pores enable gas molecules to diffuse across the shell, while the exceptionally hydrophobic interior surface effectively repels water. Comparative structural analysis confirms the evolutionary conservation of gas vesicle assemblies and demonstrates molecular features of shell reinforcement by GvpC. Our findings will further research into gas vesicle biology and facilitate molecular engineering of gas vesicles for ultrasound imaging.

DOI: 10.1016/j.cell.2023.01.041

Source: https://www.cell.com/cell/fulltext/S0092-8674(23)00100-9