Related Experiment Video
Updated: Sep 26, 2026
Imaging and Quantifying Mitochondrial Morphology in C. elegans During Aging
Published on: January 17, 2025
Deletion of mdmB impairs mitochondrial distribution and morphology in Aspergillus nidulans
Katrin V Koch1, Rüdiger Suelmann, Reinhard Fischer
1Department of Microbiology, University of Marburg and Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., D-35043 Marburg, Germany.
Abstract:
Mitochondria form a dynamic network of interconnected tubes in the cells of Saccharomyces cerevisiae or filamentous fungi such as Aspergillus nidulans, Neurospora crassa, or Podospora anserina. The dynamics depends on the separation of mitochondrial fragments, their movement throughout the cell, and their subsequent fusion with the other parts of the organelle. Interestingly, the microtubule network is required for the distribution in N. crassa and S. pombe, while S. cerevisiae and A. nidulans appear to use the actin cytoskeleton. We studied a homologue of S. cerevisiae Mdm10 in A. nidulans, and named it MdmB. The open reading frame is disrupted by two introns, one of which is conserved in mdm10 of P. anserina. The MdmB protein consists of 428 amino acids with a predicted molecular mass of 46.5 kDa. MdmB shares 26% identical amino acids to Mdm10 from S. cerevisiae, 35% to N. crassa, and 32% to the P. anserina homologue. A MdmB-GFP fusion protein co-localized evenly distributed along mitochondria. Extraction of the protein was only possible after treatment with a non-ionic and an ionic detergent (1% Triton X-100; 0.5% SDS) suggesting that MdmB was tightly bound to the mitochondrial membrane fraction. Deletion of the gene in A. nidulans affected mitochondrial morphology and distribution at 20 degrees C but not at 37 degrees C. mdmB deletion cells contained two populations of mitochondria at lower temperature, the normal tubular network plus some giant, non-motile mitochondria.
Insights
Researchers identified MdmB, a protein crucial for mitochondrial dynamics in Aspergillus nidulans. Deleting MdmB disrupts mitochondrial shape and movement at cooler temperatures, impacting cell health.
Area of Science:
- Cell Biology
- Mitochondrial Dynamics
- Fungal Genetics
Background:
- Mitochondria form dynamic networks essential for cellular function.
- Organelle distribution relies on cytoskeletal elements, with variations across species.
- The role of specific proteins in mitochondrial dynamics is an active area of research.
Purpose of the Study:
- To investigate the function of a homologue of Saccharomyces cerevisiae Mdm10 in Aspergillus nidulans, designated MdmB.
- To characterize the MdmB protein and its role in mitochondrial morphology and distribution.
Main Methods:
- Gene identification and sequencing of the MdmB homologue in A. nidulans.
- Construction and expression of a MdmB-Green Fluorescent Protein (GFP) fusion.
- Biochemical extraction to determine MdmB's membrane association.
- Gene deletion studies to assess MdmB's function under different temperature conditions.
Main Results:
- MdmB shares sequence homology with known mitochondrial proteins in other fungi.
- MdmB-GFP localizes to mitochondria, and the protein is tightly associated with mitochondrial membranes.
- Deletion of the mdmB gene in A. nidulans leads to abnormal mitochondrial morphology and distribution at 20°C, but not at 37°C.
- mdmB deletion cells exhibit both normal tubular and giant, non-motile mitochondria at the lower temperature.
Conclusions:
- MdmB is a novel protein involved in maintaining mitochondrial network integrity and distribution in A. nidulans.
- Temperature-dependent effects of mdmB deletion suggest a role in mitochondrial adaptation or specific cellular processes at lower temperatures.
- MdmB is likely a membrane-bound protein critical for mitochondrial structural organization.
