Akiyama, Yoshinori; Ehrmann, Michael; Kihara, Akio; Ito, Koreaki:
Polypeptide binding of Escherichia coil FtsH (HflB)
In: Molecular Microbiology, Jg. 28 (1998), Heft 4, S. 803 - 812
1998Artikel/Aufsatz in Zeitschrift
BiologieFakultät für Biologie
Polypeptide binding of Escherichia coil FtsH (HflB)
Akiyama, Yoshinori; Ehrmann, MichaelLSF; Kihara, Akio; Ito, Koreaki


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.