Molecular cloning and characterization of the Caenorhabditis elegans elongation factor 2 gene (eft-2).
A Caenorhabditis elegans lambda ZAP cDNA library was screened using a fragment amplified from highly conserved regions of the mammalian and Drosophila elongation factor 2 (EF-2). Two types of cDNA clones were obtained, corresponding to two mRNA species with 3'-untranslated regions of 60 and 115 nucleotides, both encoding identical polypeptides. Sequence analysis of these clones and comparisons with hamster and Drosophila EF-2 sequences suggests that they encode C. elegans EF-2. Clone pCef6A, encoding the entire C. elegans EF-2 mRNA sequence including 45 nucleotides of 5'-untranslated region, contains a 2,556-bp open reading frame which predicts a polypeptide of 852 amino acid residues (Mr 94,564). The deduced amino acid sequence is greater than 80% identical to that of mammalian and Drosophila EF-2. Conserved sequence segments shared among a variety of GTP-binding proteins are found in the amino-terminal region. The carboxy-terminal half contains segments unique to EF-2 and its prokaryotic homolog, EF-G, as well as the histidyl residue which is ADP-ribosylated by diphtheria toxin. The C. elegans protein contains a 12-amino-acid insertion between positions 90 and 100, and a 13-amino-acid deletion between positions 237 and 260, relative to hamster EF-2. Partial sequencing of a genomic clone encoding the entire C. elegans EF-2 gene (named eft-2) has so far revealed two introns of 48 and 44 bp following codons Gln-191 and Gln-250, respectively. Southern and Northern blot analyses indicate that eft-2 is a single-copy gene and encodes a 3-kb mRNA species which is present throughout nematode development.
Ofulue
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Department of Biochemistry, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Candido
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002107:Caenorhabditis / Q000235:genetics*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D008969:Molecular Sequence Data; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000235:genetics*; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D012333:RNA, Messenger; D004247:DNA