FIG 1.

Regulation of LPS biosynthesis. (A) The biosynthesis of LPS and PL depends upon a common precursor (R-3-hydroxy-myristoyl-acyl carrier protein [ACP]). The first step in LPS biosynthesis is carried out by LpxA and is reversible. The first committed step is carried out by LpxC, a deacetylase. The first committed step in PL biosynthesis is carried out by FabZ, a dehydratase. LPS is in the outer leaflet of the OM, and PL is found in the inner leaflet. (B) The level of LpxC depends upon the activity of the FtsH/YciM protease complex which is regulated by YejM, which may sense the level of an LPS intermediate.