Quantitative aspects of the use of bacterial chloramphenicol acetyltransferase as a reporter system in the yeast Saccharomyces cerevisiae

The quantitative aspects of the use of the reporter system chloramphenicol acetyltransferase (CAT) has been evaluated in the yeast Saccharomyces cerev isiae. It was found that the CAT activity measured with a radiosotopic fluo r diffusion assay was strongly dependent on the amount of yeast extract app lied, both when CAT was expressed endogenously and when a purified Escheric hia coli enzyme was investigated. Desalting the yeast extract by gel filtra tion partly eliminated the problem, indicating that some low-molecular-weig ht compound was involved in the phenomenon. However, the extract still exhi bited stability problems on ice. An immunological CAT assay was tested and found to yield satisfactory quantitative result. (C) 1999 Academic Press.