A Model of Lipid A Biosynthesis in E . coli

lipopolysaccharide, itself a major component of the Gramnegative bacterial outer membrane. We modeled the nine enzyme-catalyzed steps its biosynthesis in E. coli, focusing particularly on biosynthesis regulation, which occurs through regulated degradation of the LpxC and WaaA enzymes. The model agrees with many experimental findings, including the lipid A production rate and the behaviors of several LpxA mutants. Flux control is dominated by LpxC if pathway regulation is ignored, but by LpxK if regulation is present. These results suggest that LpxK may be a useful drug target.