An internal region of the RpoH heat shock transcription factor is critical for rapid degradation by the FtsH protease.
The proteolysis of regulatory proteins plays an important role in the control of gene expression. The Escherichia coli heat shock sigma factor RpoH (sigma(32)) is highly unstable. Its instability is determined by interactions with the DnaK chaperone machine, RNA polymerase and the ATP-dependent protease FtsH. Bradyrhizobium japonicum expresses three RpoH proteins of which RpoH(1) is highly stable. To determine which regions of E. coli RpoH determine protein lability, we generated a number of truncated versions and hybrid proteins. Truncation of N-terminal amino acids had no, and deletion of C-terminal amino acids only a minor effect on stability of RpoH. A major determinant of RpoH lability was mapped to a region of about 85 amino acids (residues 36-122) roughly comprising the sigma factor region 2. This is the first demonstration of an internal RpoH region being responsible for FtsH-mediated degradation.
Institut fur Mikrobiologie, ETH-Zentrum, Zürich, Switzerland.
D
D
Bertani
A B
AB
Oppenheim
F
F
Narberhaus
D049069:ATP-Dependent Proteases; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D020369:Bradyrhizobium / Q000201:enzymology; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*; D001616:beta-Galactosidase / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C069774:heat-shock sigma factor 32; D001616:beta-Galactosidase; D049069:ATP-Dependent Proteases; C513383:FtsH protein, E coli; C063842:dnaK protein, E coli