Gene disruption is an important method for genetic analysis in Sacchar
omyces cerevisiae. We have designed a polymerase chain reaction-direct
ed gene disruption cassette that allows rapid disruption of genes in S
. cerevisiae without previously cloning them. In addition, this casset
te allows recycling of URA3, generating gene disruptions without the p
ermanent loss of the ura3 marker. An indefinite number of disruptions
can therefore be made in the same strain.