Altered expression of selectable marker URA3 in gene-disrupted Candida albicans strains complicates interpretation of virulence studies.
The ura-blaster technique for the disruption of Candida albicans genes has been employed in a number of studies to identify possible genes encoding virulence factors of this fungal pathogen. In this study, the URA3-encoded orotidine 5'-monophosphate (OMP) decarboxylase enzyme activities of C. albicans strains with ura-blaster-mediated genetic disruptions were measured. All strains harboring genetic lesions via the ura-blaster construct showed reduced OMP decarboxylase activities compared to that of the wild type when assayed. The activity levels in different gene disruptions varied, suggesting a positional effect on the level of gene expression. Because the URA3 gene of C. albicans has previously been identified as a virulence factor for this microorganism, our results suggest that decreased virulence observed in strains constructed with the ura-blaster cassette cannot accurately be attributed, in all cases, to the targeted genetic disruption. Although revised methods for validating a URA3-disrupted gene as a target for antifungal drug development could be devised, it is clearly desirable to replace URA3 with a different selectable marker that does not influence virulence.
Microbiology Department, University of Tennessee, Knoxville, Tennessee 37919, USA.
J
J
Lay
L K
LK
Henry
J
J
Clifford
Y
Y
Koltin
C E
CE
Bulawa
J M
JM
Becker
D000818:Animals; D002176:Candida albicans / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D004789:Enzyme Activation / Q000235:genetics; D005656:Fungal Proteins / Q000096:biosynthesis* / Q000235:genetics*; D017353:Gene Deletion; D018628:Gene Dosage; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D051379:Mice; D016254:Mutagenesis, Insertional; D009964:Orotidine-5'-Phosphate Decarboxylase / Q000235:genetics / Q000378:metabolism; D014774:Virulence / Q000235:genetics
D005656:Fungal Proteins; D009964:Orotidine-5'-Phosphate Decarboxylase