In situ cryo-electron tomography reveals the asymmetric architecture of mammalian sperm axonemes

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bioRxiv. 2022 May 16;. doi: 10.1101/2022.05.15.492011

In situ cryo-electron tomography reveals the asymmetric architecture of mammalian sperm axonemes Vale LabCryo-Electron Microscopy

Chen Zhen, Greenan Garrett, Shiozaki Momoko, Liu Yanxin, Skinner Will, Zhao Xiaowei, Zhao Shumei, Yan Rui, Guo Caiying, Yu Zhiheng, Lishko Polina, Agard David, Vale Ronald

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Abstract

The flagella of mammalian sperm display non-planar, asymmetric beating, in contrast to the planar, symmetric beating of flagella from sea urchin sperm and unicellular organisms. The molecular basis of this difference is unclear. Here, we perform in situ cryo-electron tomography of mouse and human sperm axonemes, providing the highest resolution structural information to date. Our subtomogram averages reveal mammalian sperm- specific protein complexes within the outer microtubule doublets, the radial spokes and nexin-dynein regulatory complexes. The locations and structures of these complexes suggest potential roles in enhancing the mechanical strength of mammalian sperm axonemes and regulating dynein-based axonemal bending. Intriguingly, we find that each of the nine outer microtubule doublets is decorated with a distinct combination of sperm- specific complexes. We propose that this asymmetric distribution of proteins differentially regulates the sliding of each microtubule doublet and may underlie the asymmetric beating of mammalian sperm.

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bioRxiv PrePrint https://doi.org/10.1101/2022.05.15.492011

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In situ cryo-electron tomography reveals the asymmetric architecture of mammalian sperm axonemes

Abstract

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