Disease relevance of YEF3

• A portion of the N terminus of Saccharomyces cerevisiae EF-3 (spanning the S5 homology region) has been cloned, expressed, and purified from E. coli [1].
• The nucleotide sequence of the gene was determined from a sequential series of subclones generated from the YEF-3 gene cloned into bacteriophage M13 [2].
• 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 [3].

High impact information on YEF3

• Based on these findings, we propose that GCN1 performs an EF3-related function in facilitating the activation of GCN2 by uncharged tRNA on translating ribosomes [4].
• The level of TEF-1 and -2 mRNA varied little among the cell morphological types studied, whereas TEF-3 mRNA was present in twofold greater quantity in sporangiospores than in either germlings or yeast cells which had been induced to undergo morphogenesis to hyphae [5].
• These results support the model that upon ATP hydrolysis, eEF3 interacts with eEF1A to help catalyze the delivery of aminoacyl-tRNA at the A-site of the ribosome [6].
• The binding of eEF3 to eEF1A is enhanced by ADP, indicating the interaction is favored post-ATP hydrolysis but is not dependent on the eEF1A-bound nucleotide [6].
• A temperature-sensitive P915L mutant in the eEF1A binding site of eEF3 has reduced ATPase activity and affinity for eEF1A [6].

Chemical compound and disease context of YEF3

• Additionally, an identical full-length form has been successfully expressed in Escherichia coli and a C-terminally truncated form of histidine-tagged eEF3 has been successfully expressed in E. coli and S. cerevisiae [7].

Biological context of YEF3

• The YEF3 gene is present in one copy/haploid genome and is essential for vegetative growth [8].
• Introduction of the YEF3 gene on a high copy number plasmid into yeast strains increases the ribosome-dependent ATPase activity [8].
• DNA sequence analysis revealed that the YEF3 gene contains an open reading frame of 1044 codons [8].
• Moreover, tetracycline-dependent repression of YEF3, CDC28 and RAM2 expression impaired cell growth [9].
• The YEF3 gene, located on chromosome xii, is essential for the survival of yeast [10].

Anatomical context of YEF3

• RLI1 is an essential yeast protein closely related in sequence to two soluble members of the ATP-binding cassette family of proteins that interact with ribosomes and function in translation elongation (YEF3) or translational control (GCN20) [11].
• Evidence was obtained which indicated that EF-3 was essential for the translation of natural mRNA as well as poly(U), was associated with polysomes but not ribosomal subunits, and was required for every cycle in the elongation phase of protein synthesis [12].
• The EF-3 purified from the cytosol by immunoaffinity chromatography was comparable to that prepared by ion-exchange chromatography [12].

Associations of YEF3 with chemical compounds

• We cloned the coding sequence of the Saccharomyces YEF3 gene in this vector and demonstrated an increase in YEF3 protein levels when cells were grown in the presence of the sugar sorbitol [13].
• A combination of 40 S subunits from yeast and "60 S" from wheat germ showed the stimulatory effect of EF-3 in polyphenylalanine synthesis (Chakraburtty, K., and Kamath, A. (1988) Int. J. Biochem. 20, 581-590) [14].
• The EF-3 effect is manifest in the presence of ATP, GTP, or ITP [14].
• The carboxy-terminus of EF-3 contains blocks of lysine boxes essential for its functional interaction with yeast ribosomes [10].
• Yeast strains containing elevated EF-3 protein levels are more sensitive to the aminoglycoside antibiotics hygromycin and paromomycin [8].

Other interactions of YEF3

• From these results, we conclude that the HEF3 gene does not encode a functional homolog of YEF3 [15].
• The stimulatory effect of EF-3 is, in many respects, distinct from that of EF-1 beta [14].
• This conclusion supports the model that an eEF3-related activity of GCN1 influences occupancy of the ribosomal decoding site by uncharged tRNA in starved cells [16].
• ELF1 (Elongation Like Factor) showed greatest homology with a Saccharomyces cerevisiae ORF (YPL226W), whose function is unknown, and lower homology with fungal elongation factor 3 (EF-3) genes [17].
• Furthermore, EF-3 was also found to display amino acid similarity to myosin proteins whose cellular function is to provide the motive force of muscle [18].

Analytical, diagnostic and therapeutic context of YEF3

• Southern blot analysis shows that YEF-3 is a single copy gene [19].
• Using a rapid affinity chromatography protocol, EF-3 was purified to homogeneity from C. albicans and shown to have an apparent molecular mass of 128 kDa [20].
• Western blot analysis of cell-free extracts of P. carinii, derived from rat, was done using a polyclonal antibody raised in rabbits to Saccharomyces cerevisiae EF-3 [21].
• DSC shows a major transition at a relatively low temperature of 39 degrees C, and a minor transition at 58 degrees C. Ultracentrifugation shows that EF-3 is a monomer; thus, these transitions could not reflect the unfolding or dissociation of a multimeric structure [22].
• In this communication the structure of EF-3 from Saccharomyces cerevisiae is characterized by differential scanning calorimetry (DSC), ultracentrifugation, and limited tryptic digestion [22].

References