Evolutionary divergence of an elongation factor 3 from Cryptococcus neoformans.
Elongation factor 3 (EF3) is considered a promising drug target for the control of fungal diseases because of its requirement for protein synthesis and survival of fungi and a lack of EF3 in the mammalian host. However, EF3 has been characterized only in ascomycete yeast. In order to understand the role of EF3 in a basidiomycete yeast, we cloned the gene encoding EF3 from Cryptococcus neoformans (CnEF3), an important fungal pathogen in immunocompromised patients, including those infected with human immunodeficiency virus. CnEF3 was found to encode a 1,055-amino-acid protein and has 44% identity with EF3 from Saccharomyces cerevisiae (YEF3). Expressed CnEF3 exhibited ATPase activity that was only modestly stimulated by ribosomes from S. cerevisiae. In contrast, CnEF3 showed tight binding to cryptococcal ribosomes, as shown by an inability to be removed under conditions which successfully remove Saccharomyces EF3 from ribosomes (0.5 M KCl or 2 M LiCl). CnEF3 also poorly complemented a YEF3 defect in a diploid null mutant and two temperature-sensitive mutants which have been shown previously to be complemented well by EF3 from other ascomycetes, such as Candida albicans. These data clearly identify the presence of a functioning EF3 in the basidiomycete yeast C. neoformans, which demonstrates an evolutionary divergence from EF3 of ascomycete yeast.
Blakely
G
G
Division of Infectious Diseases, University of Illinois at Chicago College of Medicine, Chicago, Illinois 60612, USA.
Hekman
J
J
Chakraburtty
K
K
Williamson
P R
PR
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D005075:Biological Evolution; D003455:Cryptococcus neoformans / Q000235:genetics*; D005656:Fungal Proteins; D008969:Molecular Sequence Data; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D011994:Recombinant Proteins / Q000096:biosynthesis; D029701:Saccharomyces cerevisiae Proteins; D015003:Yeasts / Q000201:enzymology
D005656:Fungal Proteins; D010445:Peptide Elongation Factors; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C111584:YEF3 protein, S cerevisiae; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases