Overexpression of cytoplasmic dynein's globular head causes a collapse of the interphase microtubule network in Dictyostelium.
Cytoplasmic dynein is a minus-end directed microtubule-based motor. Using a molecular genetic approach, we have begun to dissect structure-function relationships of dynein in the cellular slime mold Dictyostelium. Expression of a carboxy-terminal 380-kDa fragment of the heavy chain produces a protein that approximates the size and shape of the globular, mechanochemical head of dynein. This polypeptide cosediments with microtubules in an ATP-sensitive fashion and undergoes a UV-vanadate cleavage reaction. The deleted amino-terminal region appears to participate in dimerization of the native protein and in binding the intermediate and light chains. Overexpression of the 380-kDa carboxy-terminal construct in Dictyostelium produces a distinct phenotype in which the interphase radial microtubule array appears collapsed. In many cells, the microtubules form loose bundles that are whorled around the nucleus. Similar expression of a central 107-kDa fragment of the heavy chain does not produce this result. The data presented here suggest that dynein may participate in maintaining the spatial pattern of the interphase microtubule network.
Koonce
M P
MP
Division of Molecular Medicine, Wadsworth Center, Albany, New York 12201-0509, USA.
Samsó
M
M
D000818:Animals; D003593:Cytoplasm / Q000201:enzymology*; D003599:Cytoskeleton / Q000648:ultrastructure; D004023:Dictyostelium / Q000648:ultrastructure; D004398:Dyneins / Q000737:chemistry / Q000502:physiology*; D007399:Interphase / Q000187:drug effects; D008854:Microscopy, Electron; D008870:Microtubules / Q000187:drug effects / Q000235:genetics*; D015394:Molecular Structure; D010641:Phenotype; D013329:Structure-Activity Relationship
D004398:Dyneins