Isolation of the DNA sequence coding indole-3-glycerol phosphate synthetase and phosphoribosylanthranilate isomerase of Schizophyllum commune.

A Schizophyllum gene library was made in plasmid pRK9. Plasmids from this library were tested for their ability to complement several auxotrophic mutations of Escherichia coli. The goal was to isolate a Schizophyllum auxotrophic gene that could be used to transform a corresponding Schizophyllum auxotrophic mutant to prototrophy. Complementation was observed only for E. coli trpC indole 3-glycerol phosphate synthetase (IGPS) and phosphoribosyl-anthranilate isomerase (PRAI) mutations. Plasmids with a Schizophyllum sequence coding for both IGPS and PRAI activities were recovered from E. coli transformants. Expression of the Schizophyllum gene (TRP1) in E. coli is probably dependent on the Serratia marcescens promoter of plasmid pRK9. The DNA sequence containing the Schizophyllum TRP1 gene was not obviously rearranged in cloning.