Abstract
Strains of Aspergillus containing the benA22 mutation are resistant to benomyl for vegetative growth but do not produce conidia. To test whether conidiation involved an additional benomyl-sensitive tubulin (i.e., was mediated by a tubulin other than the tubulins coded for by the benA locus), a collection of mutants was produced that formed conidia in the presence of benomyl, i.e., were conidiation-resistant (CR-) mutants. We analyzed the tubulins of these CR- mutants using two- dimensional gel electrophoresis and found that the mutants lacked one species of beta-tubulin (designated beta 3). We have examined two of these mutants in detail. In crosses with strains containing wild-type tubulins, we found that the absence of the beta 3-tubulin co-segregated perfectly with the CR- phenotype. In diploids containing both the benA22 and CR- mutations, we found that the CR- phenotype was recessive and that beta 3-tubulin was present on two-dimensional gels of tubulins prepared from these diploids. In another set of crosses, these two CR- strains and seven others were first made auxotrophic for uridine and then crossed against strains that had homologously integrated a plasmid containing an incomplete internal fragment of the beta 3-tubulin gene and the pyr4 gene of Neurospora crassa (which confers uridine prototrophy on transformants). If the CR- phenotype were produced by a mutation in a gene distinct from the structural gene for beta 3-tubulin (designated the tubC gene), then crossing over should have produced some CR+ segregants among the uridine auxotrophic progeny of the second cross. All of the uridine auxotrophs from this type of cross, however, showed the CR- phenotype, suggesting that the mutation in these strains is at or closely linked to the tubC locus. The most obvious explanation of these results is that beta 3-tubulin is ordinarily used during conidiation and the presence of this species of beta-tubulin renders conidiation sensitive to benomyl. In the CR- mutants, beta 3-tubulin is absent, and in the presence of the benA22 mutation the benomyl- resistant beta 1-and/or beta 2-tubulin substitutes for beta 3 to make conidiation benomyl resistant. We discuss these results and give two models to explain the interactions between these beta-tubulin species.
Full Text
The Full Text of this article is available as a PDF (715.2 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Burnette W. N. "Western blotting": electrophoretic transfer of proteins from sodium dodecyl sulfate--polyacrylamide gels to unmodified nitrocellulose and radiographic detection with antibody and radioiodinated protein A. Anal Biochem. 1981 Apr;112(2):195–203. doi: 10.1016/0003-2697(81)90281-5. [DOI] [PubMed] [Google Scholar]
- Fairbanks G., Steck T. L., Wallach D. F. Electrophoretic analysis of the major polypeptides of the human erythrocyte membrane. Biochemistry. 1971 Jun 22;10(13):2606–2617. doi: 10.1021/bi00789a030. [DOI] [PubMed] [Google Scholar]
- Glisin V., Crkvenjakov R., Byus C. Ribonucleic acid isolated by cesium chloride centrifugation. Biochemistry. 1974 Jun 4;13(12):2633–2637. doi: 10.1021/bi00709a025. [DOI] [PubMed] [Google Scholar]
- Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
- May G. S., Gambino J., Weatherbee J. A., Morris N. R. Identification and functional analysis of beta-tubulin genes by site specific integrative transformation in Aspergillus nidulans. J Cell Biol. 1985 Sep;101(3):712–719. doi: 10.1083/jcb.101.3.712. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Morris N. R., Kirsch D. R., Oakley B. R. Molecular and genetic methods for studying mitosis and spindle proteins in Aspergillus nidulans. Methods Cell Biol. 1982;25(Pt B):107–130. doi: 10.1016/s0091-679x(08)61422-3. [DOI] [PubMed] [Google Scholar]
- O'Farrell P. H. High resolution two-dimensional electrophoresis of proteins. J Biol Chem. 1975 May 25;250(10):4007–4021. [PMC free article] [PubMed] [Google Scholar]
- Oakley B. R., Morris N. R. A beta-tubulin mutation in Aspergillus nidulans that blocks microtubule function without blocking assembly. Cell. 1981 Jun;24(3):837–845. doi: 10.1016/0092-8674(81)90109-4. [DOI] [PubMed] [Google Scholar]
- Oakley B. R., Morris N. R. Nuclear movement is beta--tubulin-dependent in Aspergillus nidulans. Cell. 1980 Jan;19(1):255–262. doi: 10.1016/0092-8674(80)90407-9. [DOI] [PubMed] [Google Scholar]
- Pelham H. R., Jackson R. J. An efficient mRNA-dependent translation system from reticulocyte lysates. Eur J Biochem. 1976 Aug 1;67(1):247–256. doi: 10.1111/j.1432-1033.1976.tb10656.x. [DOI] [PubMed] [Google Scholar]
- Sedmak J. J., Grossberg S. E. A rapid, sensitive, and versatile assay for protein using Coomassie brilliant blue G250. Anal Biochem. 1977 May 1;79(1-2):544–552. doi: 10.1016/0003-2697(77)90428-6. [DOI] [PubMed] [Google Scholar]
- Sheir-Neiss G., Lai M. H., Morris N. R. Identification of a gene for beta-tubulin in Aspergillus nidulans. Cell. 1978 Oct;15(2):639–647. doi: 10.1016/0092-8674(78)90032-6. [DOI] [PubMed] [Google Scholar]
- Shortle D., Haber J. E., Botstein D. Lethal disruption of the yeast actin gene by integrative DNA transformation. Science. 1982 Jul 23;217(4557):371–373. doi: 10.1126/science.7046050. [DOI] [PubMed] [Google Scholar]
- Weatherbee J. A., Morris N. R. Aspergillus contains multiple tubulin genes. J Biol Chem. 1984 Dec 25;259(24):15452–15459. [PubMed] [Google Scholar]