Involvement of the <Emphasis Type="Italic">N</Emphasis>-terminal region and its characteristic coiled-coil fragment in the function and structure maintenance of <Emphasis Type="Italic">E. coli</Emphasis> LonA protease

The truncated form of E. coli LonA protease (EcLon) lacking the N-terminal fragment 1–172 (Lon173) and the variant with deleted coiled-coil (CC) fragment 173–283 (dCC-Lon, a deletion form) are produced and characterized to study the role of the N-terminal region in the functioning of this protease. A comparative analysis of the properties of full-length EcLon protease, dCC-Lon, and Lon173 as well as an earlier produced form with retained C-terminal region (235–280) of CC fragment, Lon235, is performed. As is shown, fragment 1–280 plays an important role in both formation of the ATPase site and maintenance of a stable EcLon protease conformation. Fragment 107–172 is of a paramount importance for implementation of the processive mechanism of ATP-dependent proteolysis.