Fig. 1. Method for transposon mutagenesis of C.albicans. Linearized C.albicans genomic DNA fragments generated by restriction enzyme digestion were added to the donor plasmid containing a modified Tn7 transposon and Tn7 transposase. The modified transposon contains a promoterless Streptococcus thermophilus lacZ (Uhl and Johnson, 2001), C.albicans URA3 (Gillum et al., 1984) and the ampicillin resistance gene (bla) and origin of replication from pBluescriptKS+ (Stratagene). The sacB gene located on the donor plasmid external to the Tn7 repeats allows for selection against the donor plasmid (see Materials and methods). Following the transposition reaction (Biery et al., 2000), mutagenized genomic DNA was ligated and transformed into E.coli. The library was amplified, linearized by digestion with BsrGI and transformed in batch into C.albicans strain CAI4 (ura3/ura3). The transformed DNA was allowed to integrate into the C.albicans genome by homologous recombination, and successful integrants were selected as URA+ transformants.