9S7G

SPACA9 and MNMIP1 bound to the seam of manchette microtubules

Summary for 9S7G

• Entry DOI: 10.2210/pdb9s7g/pdb
• EMDB information: 54641
• Descriptor: Tubulin beta-4B chain, Tubulin alpha-1A chain, Sperm acrosome-associated protein 9, ... (7 entities in total)
• Functional Keywords: microtubule, cytosolic protein
• Biological source: Rattus norvegicus (Norway rat); More
• Total number of polymer chains: 6
• Total formula weight: 220661.71

Authors

Judernatz, J.H.,Zhang, R.,Zeev-Ben-Mordehai, T. (deposition date: 2025-08-04, release date: 2026-06-17, Last modification date: 2026-07-29)

Primary citation

Judernatz, J.H.,Doroshev, S.,Hoogebeen, R.A.,Jonkers, S.,Schweizer, D.,Gravett, M.S.C.,Bromfield, E.G.,Howes, S.C.,Akhmanova, A.,Zhang, R.,Zeev-Ben-Mordehai, T.
SPACA9 and MNMIP1 bridge the seam of spermatid manchette microtubules.
Embo J., 45:5024-5045, 2026

PubMed Abstract: 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.

PubMed: 42286192
DOI: 10.1038/s44318-026-00833-w

Experimental method

ELECTRON MICROSCOPY (3.2 Å)