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Anne-Marie Tassin — Procentriole assembly revealed by cryo-electron tomography

Speaker :

Anne-Marie Tassin, INSERM - Institut Curie, Orsay

When :

Wednesday 12 May

Where :

C023 (RDC LR6 côté Centre Blaise Pascal)

Title :

Procentriole assembly revealed by cryo-electron tomography

Abstract :

Centrosomes are cellular organelles that play a major role in the spatial organisation of the microtubule network. The centrosome is comprised of two centrioles that duplicate only once during the cell cycle, generating a procentriole from each mature centriole. Despite the essential roles of centrosomes, the detailed structural mechanisms involved in centriole duplication remain largely unknown. Here, we describe human procentriole assembly using cryo-electron tomography. In centrosomes isolated from human lymphoblasts, we found that each one of the nine microtubule triplets grows independently around a periodic central structure. The proximal end of the A-microtubule is capped by a conical structure and the B- and C-microtubules elongate bidirectionally from its wall. These observations suggest that the gamma tubulin ring complex („-TuRC) plays a fundamental role in procentriole formation by nucleating the A-microtubule, which acts as a template for B-microtubule elongation that, in turn, supports C-microtubule growth. This work provides new insights into the initial structural events involved in procentriole assembly and establishes the basis for determining the molecular mechanisms of centriole duplication on the nanometric scale.

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