Disruption of the hslU gene, which encodes an ATPase subunit of the eukaryotic 26S proteasome homolog in Escherichia coli, suppresses the temperature-sensitive dnaA46 mutation.

The Escherichia coli hslVU genes encode subunits of an ATP-dependent protease, a homolog of the eukaryotic 26S proteasome. We found that the hslU gene is required for the temperature (40 degrees C)-sensitive phenotype of the dnaA46 mutant, while other soluble ATP-dependent proteases, La (Lon) and Ti (Clp), were unrelated to this dnaA46 phenotype. Disruption of the hslU gene inhibited cell growth at high temperatures. These observations suggest a specific in vivo role for HslVU protease in denatured proteins. As the absence of HslU produces minicells in M9 medium, the protease may be involved in the cell cycle regulation.