title: Precursor for elongation factor Tu from Escherichia coli.
abstract: The tufA gene, one of two genes in Escherichia coli encoding elongation factor Tu (EF-Tu), was cloned into a ColE1-derived plasmid downstream of the lac promoter-operator. In cells carrying this plasmid, the synthesis of EF-Tu was increased four- to fivefold upon the addition of isopropyl-beta-D-thiogalactopyranoside (an inducer of the lac promoter). This condition led to the synthesis of a novel protein, called pTu, which comigrated with EF-Tu on a sodium dodecyl sulfate-polyacrylamide gel but could be separated on an isoelectric focusing gel, since pTu is slightly more basic than EF-Tu. The synthesis of pTu could also be induced by the synthesis of a hybrid protein containing just the amino-terminal half of the EF-Tu protein. Genetic data suggest that pTu is the product of the tufA and tufB genes. The pTu protein was shown to be related to EF-Tu by gel electrophoresis of tryptic peptides. Pulse-chase experiments suggest that pTu is a precursor of EF-Tu. Interestingly, in a classic membrane fractionation procedure, EF-Tu was found in the cytosolic fraction, whereas pTu was partitioned with the outer membrane.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D046911:Macromolecular Substances; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D046911:Macromolecular Substances; D010445:Peptide Elongation Factors; D011498:Protein Precursors; C036506:elongation factor T