Calcium signaling is involved in dynein-dependent microtubule organization.
The microtubule cytoskeleton supports cellular morphogenesis and polar growth, but the underlying mechanisms are not understood. In a screen for morphology mutants defective in microtubule organization in the fungus Ustilago maydis, we identified eca1 that encodes a sarcoplasmic/endoplasmic calcium ATPase. Eca1 resides in the endoplasmic reticulum and restores growth of a yeast mutant defective in calcium homeostasis. Deletion of eca1 resulted in elevated cytosolic calcium levels and a severe growth and morphology defect. While F-actin and myosin V distribution is unaffected, Deltaeca1 mutants contain longer and disorganized microtubules that show increased rescue and reduced catastrophe frequencies. Morphology can be restored by inhibition of Ca(2+)/calmodulin-dependent kinases or destabilizing microtubules, indicating that calcium-dependent alterations in dynamic instability are a major cause of the growth defect. Interestingly, dynein mutants show virtually identical changes in microtubule dynamics and dynein-dependent ER motility was drastically decreased in Deltaeca1. This indicates a connection between calcium signaling, dynein, and microtubule organization in morphogenesis of U. maydis.
Adamíková
L'ubica
L
Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strabetae, D-35043 Marburg, Germany.
Straube
Anne
A
Schulz
Irene
I
Steinberg
Gero
G
D000199:Actins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004398:Dyneins / Q000235:genetics / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005838:Genotype; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D024701:Myosin Type V / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D015398:Signal Transduction; D013696:Temperature; D014588:Ustilago / Q000378:metabolism
D000199:Actins; D024701:Myosin Type V; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D004398:Dyneins; D000252:Calcium-Transporting ATPases; D002118:Calcium