Akiyama, Yoshinori; Ehrmann, Michael; Kihara, Akio; Ito, Koreaki:

Polypeptide binding of Escherichia coil FtsH (HflB)

In: Molecular Microbiology, Jg. 28 (1998) ; Nr. 4, S. 803-812
ISSN: 0950-382X
Zeitschriftenaufsatz / Fach: Biologie
ehem. Fakultät für Biologie und Geografie
The Escherichia coli FtsH protein is a membrane-bound and ATP-dependent protease. In this study, we describe ATP-dependent conformational changes in FtsH as well as a polypeptide binding ability of this protein. A 33 kDa segment of FtsH became trypsin resistant in the presence of ATP. ATP and ATPγS prevented self-aggregation of detergent-solubilized FtsH-His6-Myc at 37°C, again suggesting that the binding of ATP induces a conformational change in FtsH. Affinity chromatography showed that FtsH-His6-Myc can associate with denatured alkaline phosphatase (PhoA) but not with the native enzyme. Denatured PhoA also prevented the aggregation of FtsH, and these two proteins co-sedimented through a sucrose gradient. Binding between FtsH- His6-Myc and detergent-solubilized SecY was also demonstrated. Although FtsH-bound SecY was processed further for ATP-dependent proteolysis, FtsH- bound PhoA was not. Thus, FtsH association with denatured PhoA is uncoupled from proteolysis. Overproduction of FtsH significantly increased the cytoplasmic localization of the PhoA moiety of a MalF-PhoA hybrid protein, in which a charged residue had been introduced into a transmembrane segment. Thus, denatured PhoA binding of FtsH may also occur in vivo.