MOLECULAR-CLONING OF A GENE ENCODING TRANSLATION INITIATION-FACTOR (TIF) FROM CANDIDA-ALBICANS

The differential display technique was applied to compare mRNAs from t wo clinical isolates of Candida albicans with different virulence; hig h (potent strain, 16240) and low (weak strain, 18084) extracellular ph ospholipase activities. Complementary DNA fragments corresponding to s everal apparently differentially expressed mRNAs were recovered and se quenced. A complementary DNA fragment seen distinctly in the potent ph ospholipase producing strain was highly homologous to the yeast transl ation initiation factor (TIF). The selected DNA fragment was then used as a probe to isolate its corresponding complementary DNA clone from a library of C. albicans genomic DNA. The sequence of isolated gene re vealed an open reading frame of 1194 nucleotides with the potential to encode a protein of 397 amino acids with a predicted molecular weight of 43 kDa. Over its entire length, the amino acid sequence showed str ong homology (78-89%) to Saccharomyces cerevisiae TIF and (63-80%) to mouse eIF-4A proteins. Therefore, our C. albicans gene was identified to be TIF (Ca TIF). Northern blot analysis in the two strains of C. al bicans revealed that Ca TIF expression is 1.5-fold higher in the poten t phospholipase producing strain. The restriction endonuclease digesti on of genomic DNA from this potent strain revealed at least two hybrid ized bands in Southern blot analysis, suggesting two or more closely r elated sequences in the C. albicans genome.