Control of the tRNA-tufB operon in Escherichia coli. 3. Feedback inhibition of tufB expression by an EF-Tu with a deletion in the guanine-nucleotide-binding domain.
The expression of tufB, one of the two EF-Tu-encoding genes in Escherichia coli, is under autogenous control. Feedback inhibition of tufB expression by plasmid-borne EF-Tu has been used to answer the question of whether or not the integrity of the guanine-nucleotide-binding domain of EF-Tu is required for the autoregulatory role of the factor protein. We show that a large deletion of tufB, causing the elimination of an 81-amino-acid segment from the plasmid-borne EF-Tu, does not abolish tufB repression. We conclude that the autoregulation of the cellular EF-Tu level is not dependent on an intact guanine-nucleotide-binding domain and does not require binding of GTP to EF-Tu. The repressor activity of the deletion derivative of EF-Tu can be measured despite a rapid disappearance of the (altered) mutant protein from the soluble cytoplasmic fraction of the cell. Degradation and assembly in larger complexes are responsible for this disappearance.
Van Delft
J H
JH
Department of Biochemistry, University of Leiden, The Netherlands.
Bosch
L
L
D002872:Chromosome Deletion; D004926:Escherichia coli / Q000235:genetics*; D005246:Feedback; D019204:GTP-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D005798:Genes, Bacterial; D006153:Guanosine Diphosphate / Q000378:metabolism; D046911:Macromolecular Substances; D009876:Operon; D010444:Peptide Elongation Factor Tu / Q000235:genetics*; D011487:Protein Conformation; D012329:RNA, Bacterial / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics*
D046911:Macromolecular Substances; D012329:RNA, Bacterial; D006153:Guanosine Diphosphate; D012343:RNA, Transfer; D019204:GTP-Binding Proteins; D010444:Peptide Elongation Factor Tu