A lumenal interrupted helix in human sperm tail microtubules

Mapping Intimacies ◽

10.1101/088476 ◽

2016 ◽

Author(s):

Davide Zabeo ◽

John M. Heumann ◽

Cindi L. Schwartz ◽

Azusa Suzuki-Shinjo ◽

Garry Morgan ◽

...

Keyword(s):

Electron Tomography ◽

Human Sperm ◽

Variable Number ◽

Human Diseases ◽

Human Spermatozoon ◽

Sperm Tail ◽

Swimming Direction ◽

Left Handed ◽

Cryo Electron Tomography ◽

Cellular Extensions

AbstractEukaryotic flagella are complex cellular extensions involved in many human diseases gathered under the term ciliopathies. Currently, detailed insights on flagellar structure come from studies on protozoa. Here, cryo-electron tomography (cryo-ET) of intact human spermatozoon tails showed a variable number of microtubules in the singlet region. Inside their lumen, a novel left-handed interrupted helix which extends several micrometers at their plus ends was discovered. This structure was named Tail Axoneme Intra-Lumenal Spiral (TAILS) and binds directly to 11 protofilaments on the internal microtubule wall, coaxial with the surrounding microtubule lattice. It leaves a gap over the microtubule seam, which was directly visualized in both singlet and doublet microtubules. We suggest that TAILS may stabilize microtubules, enable rapid swimming or play a role in controlling the swimming direction of spermatozoa.

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The in situ structure of Parkinson’s disease-linked LRRK2

10.1101/837203 ◽

2019 ◽

Cited By ~ 7

Author(s):

Reika Watanabe ◽

Robert Buschauer ◽

Jan Böhning ◽

Martina Audagnotto ◽

Keren Lasker ◽

...

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Electron Tomography ◽

Double Helix ◽

Pathogenic Mutation ◽

Left Handed ◽

Cellular Environment ◽

Cryo Electron Tomography ◽

Subtomogram Averaging

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most frequent cause of familial Parkinson’s disease. LRRK2 is a multi-domain protein containing a kinase and GTPase. Using in situ cryo-electron tomography and subtomogram averaging, we reveal a 14-Å structure of LRRK2 bearing a pathogenic mutation that oligomerizes as a right-handed double-helix around microtubules, which are left-handed. Using integrative modeling, we determine the architecture of LRRK2, showing that the GTPase points towards the microtubule, while the kinase is exposed to the cytoplasm. We identify two oligomerization interfaces mediated by non-catalytic domains. Mutation of one of these abolishes LRRK2 microtubule-association. Our work demonstrates the power of cryo-electron tomography to obtain structures of previously unsolved proteins in their cellular environment and provides insights into LRRK2 function and pathogenicity.

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Axonemal doublet microtubules can split into two complete singlets in human sperm flagellum tips

10.1101/562777 ◽

2019 ◽

Author(s):

Davide Zabeo ◽

Jacob T Croft ◽

Johanna L Höög

Keyword(s):

Embryonic Development ◽

Electron Tomography ◽

Human Sperm ◽

Human Spermatozoa ◽

Model Organisms ◽

Sperm Flagellum ◽

Human Fertility ◽

Cryo Electron Tomography ◽

Health And Disease

AbstractMotile flagella are crucial for human fertility and embryonic development. The distal tip of the flagellum is where growth and intra-flagellar transport are coordinated. In most, but not all, model organisms the distal tip includes a “singlet region”, where axonemal doublet microtubules terminate and only complete A-tubules extend as singlet microtubules to the tip. How a human flagellar tip is structured is unknown. Here, the flagellar tip structure of human spermatozoa was investigated by cryo-electron tomography, revealing the formation of two complete singlet microtubules from both the A-tubule and B-tubule of doublet microtubules. This different tip arrangement in human spermatozoa shows the need to investigate human flagella directly in order to understand their role in our health and disease.

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