ELONGATION-FACTOR-3 (EF-3) FROM CANDIDA-ALBICANS SHOWS BOTH STRUCTURAL AND FUNCTIONAL SIMILARITY TO EF-3 FROM SACCHAROMYCES-CEREVISIAE

As with many other fungi, including the budding yeast Saccharomyces cerevisiae, the dimorphic fungus Candida albicans encodes the novel translation factor, elongation factor 3 (EF-3). Using a rapid affinity chromatography protocol, EF-3 was purified to homogeneity from C. albicans and shown to have an apparent molecular mass of 128kDa. A polyclonal antibody raised against C. albicans EF-3 also showed cross-reactivity with EF-3 from S. cerevisiae. Similarly, the S. cerevisiae TEF3 gene (encoding EF-3) showed cross-hybridization with genomic DNA from C. albicans in Southern hybridization analysis, demonstrating the existence of a single gene closely related to TEF3 in the C. albicans genome. This gene was cloned by using a 0.7kb polymerase chain reaction-amplified DNA fragment to screen a C. albicans gene library. DNA sequence analysis of 200 bp of the cloned fragment demonstrated an open reading frame showing 51% predicted amino acid identity between the putative C. albicans EF-3 gene and its S. cerevisiae counterpart over the encoded 65-amino-acid stretch. That the cloned C. albicans sequence did indeed encode EF-3 was confirmed by demonstrating its ability to rescue an otherwise non-viable S. cerevisiae tef3:HIS3 null mutant. Thus EF-3 from C. albicans shows both structural and functional similarlity to EF-3 from S. cerevisiae.