Abstract
Positioning organelles at the right place and time is critical for their function and inheritance. In budding yeast, mitochondrial and nuclear positioning require the anchoring of mitochondria and dynein to the cell cortex by clusters of Num1. We have previously shown that mitochondria drive the assembly of cortical Num1 clusters, which then serve as anchoring sites for mitochondria and dynein. When mitochondrial inheritance is inhibited, mitochondrial-driven assembly of Num1 in buds is disrupted and defects in dynein-mediated spindle positioning are observed. Using a structure-function approach to dissect the mechanism of mitochondria-dependent dynein anchoring, we found that the EF hand–like motif (EFLM) of Num1 and its ability to bind calcium are required to bias dynein anchoring on mitochondria-associated Num1 clusters. Consistently, when the EFLM is disrupted, we no longer observe defects in dynein activity following inhibition of mitochondrial inheritance. Thus, the Num1 EFLM functions to bias dynein anchoring and activity in nuclear inheritance subsequent to mitochondrial inheritance. We hypothesize that this hierarchical integration of organelle positioning pathways by the Num1 EFLM contributes to the regulated order of organelle inheritance during the cell cycle.
| Original language | English (US) |
|---|---|
| Article number | ar20 |
| Journal | Molecular biology of the cell |
| Volume | 33 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2022 |
Funding
We thank members of the Lackner lab and Jennifer Brace for suggestions and critical scientific discussions. We also thank Northwestern’s Cell Biology Supergroup and the Wignall-Lackner Cell Biology Group for constructive feedback on the project. We are extremely grateful to Jessica Hornick and Arabela Grigorescu for their help and advice on imaging and ITC, respectively. All microscopy was performed at the Biological Imaging Facility at Northwestern University (RRID:SCR_017767), supported by the Chemistry for Life Processes Institute, the Northwestern University Office for Research, the Department of Molecular Biosciences, and the Rice Foundation. The ITC was performed by the Northwestern University Keck Biophysics Facility, supported by a Cancer Center Support Grant (NCI CA060553). We also thank Luke Lavis from Janelia for providing the JFX650 dye for the HaloTag imaging experiments. H.L.A. was supported by American Heart Association Predoctoral Fellowship 19PRE34381053. L.L.L. is supported by National Institutes of Health, National Institute of General Medical Sciences grant R01GM120303.
ASJC Scopus subject areas
- General Medicine