Yeast pericentrin/Spc110 contains multiple domains required for tethering the gamma tubulin complex to the centrosome

• Published in: Molecular biology of the cell 2020-07, Vol.31 (14), p.mbcE20020146-1452
• Main Authors: Alonso, Annabel, Fabritius, Amy, Ozzello, Courtney, Andreas, Mike, Klenchin, Dima, Rayment, Ivan, Winey, Mark
• Format: Article
• Language: English
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.E20-02-0146

The spindle pole body (SPB) serves as the sole microtubule-organizing center (MTOC) of the cell, nucleating both cytoplasmic and nuclear microtubules. Yeast pericentrin, Spc110, binds to and activates the gamma tubulin complex via its N terminus, allowing nuclear microtubule polymerization to occur. The Spc110 C terminus links the gamma tubulin complex to the central plaque of the SPB by binding to Spc42, Spc29, and calmodulin. Here, we show that overexpression of the C terminus of Spc110 is toxic to cells and correlates with its localization to the SPB. Spc110 domains that are required for SPB localization and toxicity include its Spc42-, Spc29-, and calmodulin-binding sites. Overexpression of the Spc110 C terminus induces spindle pole body defects and disrupts microtubule organization in both cycling and G2/M arrested cells. Notably, the two mitotic SPBs are affected in an asymmetric manner such that one SPB appears to be pulled away from the nucleus towards the cortex but remains attached via a thread of nuclear envelope. This SPB also contains relatively fewer microtubules and less endogenous Spc110. Our data suggests that overexpression of the Spc110 C terminus acts as a dominant-negative mutant that titrates endogenous Spc110 from the SPB causing spindle defects.