title: Nucleotide sequence of a Euglena gracilis chloroplast genome region coding for the elongation factor Tu; evidence for a spliced mRNA.
abstract: We characterize a 1.95 kb transcription product of the Euglena gracilis chloroplast DNA fragment Eco-N + Q by S1 nuclease analysis and DNA sequencing and show that it is the product of three splicing events. Exon 1 (0.45 kb), exon 2 (0.74 kb) and 175 nucleotides of exon 3 (0.53 kb) code for the chloroplast elongation factor protein (EF-Tu). The remaining part of exon 3 and exon 4 (0.23 kb) have unidentified open reading frames. The chloroplast EF-Tu protein has 408 aminoacids and is to 70% homologous with the E. coli EF-Tu protein. The active site for aminoacyl-tRNA binding is highly conserved, while the active site for GTP/GDP binding lacks the cysteine present in the E. coli EF-Tu protein. The two introns separating exons 1, 2 and 3 are, respectively, 103 and 110 nucleotides long. The size of the third intron is not yet determined. The splicing rules for eukaryote mRNA are not followed.
mesh_terms: D000595:Amino Acid Sequence; D001482:Base Composition; D001483:Base Sequence; D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D005056:Euglena gracilis / Q000235:genetics*; D005796:Genes; D009693:Nucleic Acid Hybridization; D010444:Peptide Elongation Factor Tu; D010445:Peptide Elongation Factors / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D010445:Peptide Elongation Factors; D012333:RNA, Messenger; D004262:DNA Restriction Enzymes; D010444:Peptide Elongation Factor Tu