Deletion of mdmB impairs mitochondrial distribution and morphology in Aspergillus nidulans.
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.
Department of Microbiology, University of Marburg and Max-Planck-Institute for Terrestrial Microbiology, Karl-von-Frisch-Str., D-35043 Marburg, Germany.
Katrin V
KV
Koch
Rüdiger
R
Suelmann
Reinhard
R
Fischer
D000595:Amino Acid Sequence / Q000235:genetics; D001233:Aspergillus nidulans / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D001483:Base Sequence / Q000235:genetics; D019069:Cell Respiration / Q000235:genetics*; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics; D008870:Microtubules / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D005656:Fungal Proteins; C089419:MDM10 protein, S cerevisiae; C482696:MdmB protein, Aspergillus nidulans; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins