Molecular analysis of the Septoria nodorum beta-tubulin gene and characterization of a benomyl-resistance mutation.
The complete nucleotide sequence of a benomyl-resistant allele of the Septoria nodorum beta-tubulin gene (tubAR) has been determined including 745 and 1024 nucleotides 5' and 3' to the tubAR coding region, respectively. tubAR encodes a 447 amino acid polypeptide which shows a high degree of homology with other fungal beta-tubulins. The gene contains three introns at codons 4, 12 and 53, uses 48 of the possible 61 sense codons and has a GC content of 59.1% in its coding region. S1 nuclease mapping has identified two transcriptional start sites 80 bp and 83 bp upstream of the translation start, and a transcriptional termination site 192 bp downstream of the stop codon. The two transcriptional start sites lie just 8 bp and 5 bp downstream of a CT motif consisting of 18 pyrimidine nucleotides interrupted by a single adenine. The wild-type allele tubA+ has been cloned using the polymerase chain reaction and the mutation producing the benomyl-resistant phenotype of tubAR mapped to a C to T transition at the first position of codon 6, resulting in a histidine to tyrosine amino acid substitution.
Cooley
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School of Biological Sciences, University of Birmingham, Edgbaston, UK.
Caten
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D000595:Amino Acid Sequence; D001482:Base Composition; D001483:Base Sequence; D001542:Benomyl / Q000494:pharmacology*; D002874:Chromosome Mapping; D004352:Drug Resistance, Microbial; D005800:Genes, Fungal / Q000235:genetics*; D007438:Introns / Q000235:genetics; D003904:Mitosporic Fungi / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014404:Tubulin / Q000187:drug effects / Q000235:genetics*
D014404:Tubulin; D001542:Benomyl