A counterselection for the tryptophan pathway in yeast: 5-fluoroanthranilic acid resistance

The ability to counterselect, as well as to select for, a genetic marker ha s numerous applications in microbial genetics. Described here is the use of 5-fluoroanthranilic acid for the counterselection of TRP1, a commonly used genetic marker in the yeast Saccharomyces cerevisiae. Counterselection usi ng 5-fluoroanthranilic acid involves antimetabolism by the enzymes of the t ryptophan biosynthetic pathway, such that trp1, trp3, trp4 or trp5 strains, which lack enzymes required for the conversion of anthranilic acid to tryp tophan, are resistant to 5-fluoroanthranilic acid. Commonly used genetic pr ocedures, such as selection for loss of a chromosomally integrated plasmid, and a replica-plating method to rapidly assess genetic linkage in self-rep licating shuttle vectors, can now be carried out using the TRP1 marker gene . In addition, novel tryptophan auxotrophs can be selected using 5-fluoroan thranilic acid. Copyright (C) 2000 John Wiley & Sons, Ltd.