Aspergillus contains multiple tubulin genes

Previous work with benomyl-resistant mutants of Aspergillus nidulans has demonstrated that the benA locus is a structural gene for beta-tubulin. Two of the benA mutants, benA22 and benA85, show altered electrophoretic mobilities on two-dimensional gels for two beta-tubulins (designated beta 1 and beta 2). These shifts of the beta 1- and beta 2-tubulins uncover a spot in the region where wild-type beta-tubulins migrate that is occluded on gels of wild-type extracts by the beta 1- and beta 2-tubulins. Evidence has now been obtained indicating that this spot represents an additional beta-tubulin (designated beta 3). Tubulin was partially purified from Aspergillus and run on one- and two-dimensional gels and the band or spot uncovered by the shift of the beta 1- and beta 2-tubulins was identified as a beta-tubulin by immunoblotting with monoclonal and affinity-purified polyclonal anti-tubulin antibodies and by one-dimensional peptide mapping. These observations show that Aspergillus contains at least two structural genes for beta-tubulins. Similar techniques have also been applied to a mutant showing altered alpha-tubulins to confirm and modify earlier observations suggesting that at least two structural genes for alpha-tubulins are also present.