1: FEBS Lett. 2000 Jul 21;477(3):224-9.

The HslU ATPase acts as a molecular chaperone in prevention of aggregation of
SulA, an inhibitor of cell division in Escherichia coli.

Seong IS, Oh JY, Lee JW, Tanaka K, Chung CH.

School of Biological Sciences, College of Natural Sciences, Seoul National
University, Seoul 151-742, South Korea.

HslVU is an ATP-dependent protease consisting of two multimeric components: the
HslU ATPase and the HslV peptidase. SulA, which is an inhibitor of cell division
and has high tendency of aggregation, is degraded by HslVU protease. Here we
show that HslU plays a role not only as a regulatory component for the
HslV-mediated proteolysis but also as a molecular chaperone. Purified HslU
prevented aggregation of SulA in a concentration-dependent fashion. This
chaperone activity required oligomerization of HslU subunits, which could be
achieved by ATP-binding or in the presence of high HslU protein concentrations.
hsl mutation reduced the SulA-mediated inhibition of cell growth and this effect
could be reversed upon overproduction of HslU, suggesting that HslU promotes the
ability of SulA to block cell growth through its chaperone function. Thus, HslU
appears to have two antagonistic functions: one as a chaperone for promotion of
the ability of SulA in cell growth inhibition by preventing SulA aggregation and
the other as the regulatory component for elimination of SulA by supporting the
HslV-mediated degradation.

PMID: 10908725 [PubMed - indexed for MEDLINE]

Related Links

    ATP-dependent degradation of SulA, a cell division inhibitor, by the HslVU
protease in Escherichia coli. [FEBS Lett. 1999] PMID:10452560
    
    Effects of the cys mutations on structure and function of the ATP-dependent
HslVU protease in Escherichia coli. The Cys287 to Val mutation in HslU uncouples
the ATP-dependent proteolysis by HslvU from ATP hydrolysis. [J Biol Chem. 1998]
PMID:9722513
    
    The ATP-dependent HslVU/ClpQY protease participates in turnover of cell
division inhibitor SulA in Escherichia coli. [J Bacteriol. 1999] PMID:10368140
    
    HslV-HslU: A novel ATP-dependent protease complex in Escherichia coli
related to the eukaryotic proteasome. [Proc Natl Acad Sci U S A. 1996]
PMID:8650174
    
    ATP binding, but not its hydrolysis, is required for assembly and
proteolytic activity of the HslVU protease in Escherichia coli. [Biochem Biophys
Res Commun. 1997] PMID:9299555