Cloning arg3, the gene for ornithine carbamoyltransferase from Saccharomyces cerevisiae: expression in Escherichia coli requires secondary mutations; production of plasmid beta-lactamase in yeast.

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Abstract
The yeast [S. cerevisiae] arg3 gene, coding for ornithine carbamoyltransferase (carbamoylphosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3), was cloned on a hybrid pBR322-2-.mu.m plasmid. The cloned gene gives a normal regulatory response in yeast. It is not expressed at 35.degree. C when a mutation preventing mRNA export from the nucleus at this temperature is included in the genetic make-up of the carrier strain. In E. coli, no functional expression can be observed from the native yeast arg3 gene. The study of a mutant plasmid (M1) producing low levels of yeast carbamoyltransferase in E. coli has permitted the localization and orientation of arg3 on the plasmid. The mutation involved is a deletion that alters the regulatory response of arg3 in yeast. The plasmid bla gene produces detectable amounts of .beta.-lactamase (penicillin amido-.beta.-lactamhydrolase, EC 3.5.2.6) in yeast; and data on the .beta.-lactamase activity associated with 1 example of the plasmid expressing arg3 (0.6 units) is reported.