, Volume 19, Issue 11-12, pp 1101-1114

The genetics and biochemistry of urease in Ustilago violacea

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Abstract

Two complementing loci in different linkage groups of the basidiomycete Ustilago violacea are involved in urease activity: a structural one (ure-1) and a second inferred to involve a permease (ure-2) locus. Two types of complementing mutations occur in the structural locus: null activity (ure-1a) and obviously reduced activity (ure-1b). The ure-2 mutants lacked urease activity in vivo on the phenol red-urea test medium, but gave extracts with wild-type activity. Extracts from wild-type strains gave one site of urease activity after polyacrylamide gel electrophoresis. A number of ure-1b mutants and active revertants from ure-1a mutants yielded electrophoretically variant urease sites. The results are discussed in terms of enzyme polymorphism in haploid eukaryotes by one (missense) or two (null, then missense) mutations.

We acknowledge financial support from the Louis Block Fund of the University of Chicago to E. D. Garber and Cellular Biology Training Grant PHS-HD-00174 and Genetics and Regulation Training Grants GM-07197 and PHS-GM-1797-02 to M. L. Baird.