Background: Only few substrates of the essential membrane-anchored protease FtsH are known. Results: New cytoplasmic and membrane-bound substrates of FtsH were trapped in vivo. Conclusion: FtsH is involved in the sulfatation of molecules, D-amino acid metabolism, and adaptation to anaerobiosis and stress conditions. Significance: The novel FtsH substrates significantly expand our knowledge on the biological functions of this fundamentally important protease.

Background: YfgM is a membrane protein under regulatory control by FtsH. Results: Growth phase-dependent degradation of YfgM in Escherichia coli requires a novel N-terminal degron. YfgM interacts with the response regulator RcsB and acts as a negative regulator. Conclusion:The YfgM degron mediates degradation under stress conditions when the Rcs pathway is needed. Significance: The study reveals a new degron and provides insights into the function of YfgM.

Summary Cell wall antigens from Coxiella burnetii were extracted by heat, ultrasonication, phenol, SDS or sodium deoxycholate. These antigens were subsequently purified by gelchromatography yielding molecular weights of 700 and 270 KD. Using gelchromatographical purification of antigens extracted by heat, ultrasonocation or phenol Coxiella antigens nearly devoid of contaminations could be obtained. Of these highly purified antigens heat extracted antigen was treated with proteases, lysozyme or metaperiodate exemplaryly. These treatments did neither destroy nor chànge its antigenic activity, except for the treatment with metaperiodate reducing the antigenic activity significantly. In further experiments heat extracted and gelchromatographically purified Coxiella antigen was used for testing bovine sera in ELISA.