Figure 1.

Schematic of the lon gene and localization of lon mutations. The heavy black line represents the lon gene. Numbering nucleotides from the A of the starting ATG, the positions of the relevant restriction sites are indicated above the line. The ATPase Walker A motif and the site-directed mutation in this site (K362Q), as well as the region around the proteolytic active site, including the S679A mutation in that site, are shown. Other residues known to be important for proteolysis activity (H665, H667, and D676) (28) also are shown.