title: DNA sequences from the str operon of Escherichia coli.
abstract: The str operon at 72 min on the Escherichia coli chromosome contains genes for ribosomal proteins (r-proteins) S12 (str or rpsL) and S7 (rpsG) and elongation factors G (fus) and Tu (tufA). The sequence of the entire S12 gene, the S12-S7 intercistronic region, and the beginning of the S7 gene is reported. Also, the sequence of the end of the S7 gene, the S7-G intercistronic region, and the beginning of the elongation fractor G gene is reported. The S12-S7 intercistronic region is 96 base pairs long, in contrast to other intercistronic regions in r-protein operons which have been found to vary from 3 to 66 base pairs. The S7-G intercistronic region is only 27 bases long, supporting the previous conclusion that r-protein and elongation factor genes are co-transcribed. A comparison of translation initiation sites of the S12 and S7 genes, and other examples of co-transcribed r-protein genes, reveals no obvious features that could account for equimolar synthesis of all r-proteins. The codon usage in the S12 and S7 genes follows the pattern observed in other r-protein genes; that is, there is a highly preferential usage of codons recognized by the most abundant of isoaccepting tRNA species. This pattern could reflect the cell's need for efficient translation or minimal errors, or both, in r-protein synthesis.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005796:Genes; D005815:Genetic Code; D009876:Operon; D010445:Peptide Elongation Factors / Q000096:biosynthesis; D014176:Protein Biosynthesis; D000091243:Ribosomal Protein S9; D012269:Ribosomal Proteins / Q000096:biosynthesis; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D010445:Peptide Elongation Factors; D000091243:Ribosomal Protein S9; D012269:Ribosomal Proteins; C000717190:RpsI protein, E coli