Genetic dissection of the dynein and dynactin complexes in Neurospora crassa /
Cytoplasmic dynein is a multisubunit, microtubule-associated,
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739668041&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Cytoplasmic dynein is a multisubunit, microtubule-associated, mechanochemical enzyme that has been identified as a retrograde transporter of various membranous organelles. In vertebrates, cytoplasmic dynein has been proposed to be required for retrograde axonal transport, organization of the Golgi, formation of endoplasmic reticulum networks, the endocytic pathway, apical transport of vesicles in polarized intestinal epithelial cells, and formation of the mitotic spindle. In fungi, dynein has been implicated in nuclear migration, nuclear distribution, and anaphase chromosome segregation. Dynactin, another multisubunit complex, is required for cytoplasmic dynein to efficiently transport vesicles along microtubules in vitro. The mechanism by which dynactin facilitates cytoplasmic dynein-dependent vesicle transport is unknown. This study is the beginning of a genetic dissection of the cytoplasmic dynein and dynactin complexes using the filamentous fungus Neurospora crassa, a rapidly growing organism that is well-characterized genetically. Starting with the morphological mutant, cot-1, we have identified partial suppressors that exhibit a phenotype previously described as ropy. Cloning and characterization of some of these ropy mutants has revealed them to be defective in subunits of both the cytoplasmic dynein heavy chain (ro-1) and the largest (pl50Glued) and most abundant (APR1) subunits of the dynactin complex (ro-3 and ro-4, respectively). We have determined that defects in either of these two complexes results in abnormal nuclear distribution but appears to have no effect on microtubule or actin organization. By making disruption strains for ro-3 and ro-4, we have shown that the dynactin complex is nonessential for viability in N. crassa. A large scale screen for cot-1 partial suppressors has yielded 23 ropy complementation groups, many of which will surely encode other subunits of the dynein and dynactin complexes. Many of these newly isolated ropy mutants exhibit unlinked noncomplementation, which suggests some type of interaction between the proteins they encode. Preliminary work with antibodies in ro-3 and ro-4 disruptions indicates that the R03 polypeptide is not present when the dynactin complex cannot be formed. |
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| Item Description: | Vita. "Major Subject: Biology". |
| Physical Description: | xi, 127 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 110-119. |