SPACA9 and MNMIP1 bridge the seam of spermatid manchette microtubules - The EMBO Journal

The manchette is a transient microtubule (MT)-based structure that is vital for the correct shaping of sperm during spermiogenesis. Throughout spermiogenesis, the manchette retains structural integrity for several days, raising the question of how its MTs are regulated. Here, using cryo-electron tomography of manchettes isolated from rat testes, we find that manchette MT ends are structurally diverse. We show that the MT-binding protein CLASP2 is present throughout the manchette and likely regulates both MT ends. Using cryo-electron microscopy single particle analysis and super-resolution microscopy, we reveal that SPACA9 and MNMIP1 (SH3D21) bind to the seam of manchette MTs from the luminal side. SPACA9 binds to both α- and β-tubulin of protofilament 1 but does not interact directly with protofilament 13, while MNMIP1 binds directly to protofilament 13. MNMIP1 further extends and threads through the MT lattice at the seam. Our study reveals a novel seam MT inner protein complex with a unique binding mode, providing a plausible explanation for MT regulation that maintains manchette integrity over an extended period.

doi.org

Critical constituents and assembly principles of centriole biogenesis in human cells

Nature Reviews Molecular Cell Biology, Published online: 27 November 2025; doi:10.1038/s41580-025-00921-5The centriole is crucial for fundamental cellular processes in eukaryotes, including cell polarity, signalling and motility. This Review discusses recent insights into the molecular architecture of centrioles and the principles governing their assembly, with a focus on human cells.

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Cryo-ET and MD simulations reveal that dynein-2 is tuned for binding to the A-tubule of the ciliary doublet | The EMBO Journal

imageimageDynein-2 is a motor protein essential for retrograde intraflagellar transport (IFT) on the A-tubule of ciliary doublet microtubules. Here, biochemical and cryo-ET analyses demonstrate that d...

embopress.org

Volume 138 Issue 20 | Journal of Cell Science | The Company of Biologists

Journal of Cell Science publishes cutting-edge science encompassing all aspects of cell biology. It is published by The Company of Biologists, a not-for-profit organisation.

journals.biologists.com

Advances in ciliary proteomics – towards cracking the hidden proteome code of cilia

Summary: This Review explores proteomic strategies for investigating cilia, tracing the evolution from early discoveries to recent advancements enabled by proximity labeling techniques.

journals.biologists.com

a man stands in front of a white board with the words keep that in mind written on it

ALT: a man stands in front of a white board with the words keep that in mind written on it

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Microtubule inner proteins – bridging structure and function in ciliary biology

Summary: Microtubule inner proteins (MIPs) have been brought into focus by the cryo-EM revolution. This Review outlines current knowledge, emerging functions, links to ciliopathies and outstanding que...

journals.biologists.com

Molecular basis for the activation of outer dynein arms in cilia

Nature Structural & Molecular Biology, Published online: 29 September 2025; doi:10.1038/s41594-025-01680-9Issa et al. show that the ciliary small guanosine triphosphatase Arl3 displaces the inhibitory regulator Shulin/DNAAF9 from the outer dynein arm, leading to motor activation.

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SUN5 forms a regular protein lattice reinforcing the sperm head-tail junction

Linker of nucleo- and cytoskeleton (LINC) complexes reside in the nuclear envelope, the double-membrane surrounding the nucleus, where they establish a physical bridge between nucleus and cytoplasm. L...

biorxiv.org

Nde1 promotes Lis1 binding to full-length autoinhibited human dynein 1 - Nature Chemical Biology

Cryo-electron microscopy and biochemical reconstitution analysis reveals that Nde1 enhances Lis1 binding to autoinhibited dynein, promoting formation of a Phi-like–Lis1 intermediate during dynein acti...

nature.com

Associate or Senior Editor, Nature Biomedical Engineering

Job Title: Associate or Senior Editor, Nature Biomedical Engineering Organization: Nature Portfolio Location: New York, Jersey City, Shanghai or Beijing – Hybrid Working Closing date: August 20, 2025 ...

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Associate Editor or Senior Editor, Nature Methods

Title: Associate or Senior Editor, Nature Methods Organization: Nature Portfolio Locations: New York, Jersey City, Shanghai or Beijing Closing Date: August 3, 2025    About Springer Nature Springer Na...

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Forces in Cell Biology

Cell generate forces to maintain normal tissue morphology and function. Cells can also sense and process forces appropriate to their correct tissue context. ...

nature.com

Microtubule end stabilisation by cooperative oligomers of Ska and Ndc80 complexes

During mitosis, properly aligned chromosomes stabilise microtubule ends with the help of kinetochores to ensure timely segregation of chromosomes. Microtubule-binding components of the human outer kinetochore, such as Ndc80 and Ska complexes, are present in multiple copies and together bind several microtubule ends, creating a highly multivalent binding interface. Whereas Ndc80:Ndc80 and Ndc80:microtubule binding is crucial for interface stability, Ndc80 alone in absence of Ska is unable to support stable kinetochore-attachments. Using cryoET, we demonstrate that oligomeric Ndc80:Ska assemblies stabilise microtubule ends against shortening by strengthening lateral contacts between tubulin protofilaments at microtubule plus-ends. We further identify a point mutation within the SKA1 microtubule-binding domain that does not affect microtubule-binding of individual Ska molecules, but does abolish Ska:Ska interactions. Finally, we report that oligomerisation of Ska, in a cooperative fashion together with the Ndc80, is necessary to maintain stable microtubule attachments both in vivo and in vitro. ### Competing Interest Statement The authors have declared no competing interest. BBSRC, BB/X014975/1, BB/W019698/1 Wellcome Trust, https://ror.org/029chgv08, 308895/Z/23/Z

biorxiv.org

The Mn-motif protein MAP6d1 assembles ciliary doublet microtubules - Nature Communications

Cilia are composed of microtubule doublets, but how they assemble is unclear. Here, the authors show that the brain-specific MAP6d1, found in neuronal primary cilia, assembles doublet microtubules and...

nature.com

Unveiling the structural spectrum of SARS-CoV-2 fusion by in situ cryo-ET | Nature Communications

SARS-CoV-2 entry into host cells is mediated by the spike protein, which drives membrane fusion. While cryo-EM reveals stable prefusion and postfusion conformations of the spike, the transient fusion intermediate states during the fusion process remain poorly understood. Here, we design a near-native viral fusion system that recapitulates SARS-CoV-2 entry and use cryo-electron tomography (cryo-ET) to capture fusion intermediates leading to complete fusion. The spike protein undergoes extensive structural rearrangements, progressing through extended, partially folded, and fully folded intermediates prior to fusion-pore formation, a process that depends on protease cleavage and is inhibited by the WS6 S2 antibody. Upon interaction with ACE2 receptor dimer, spikes cluster at membrane interfaces and following S2’ cleavage concurrently transition to postfusion conformations encircling the hemifusion and initial fusion pores in a distinct conical arrangement. S2’ cleavage is indispensable fo

doi.org