Escherichia Coli LPS-transport protein LptA

Lipopolysaccharide (LPS) is the major constituent of the outer membrane (OM) of most Gram-negative bacteria, providing a barrier against antibiotics. LPS is synthesized at the inner membrane (IM), transported across the periplasm and assembled at the OM by the multiprotein Lpt complex. LptA is the periplasmic component of the Lpt complex, which bridges IM and OM and ferries LPS across the periplasm. How the cell co-ordinates the processes involved in OM biogenesis is not completely understood. We have generated a partial loss of function mutant in lptA, which exhibits increased sensitivity to antibiotics and isolated two classes of suppressors of this mutant. The analysis of the suppressors reveals different strategies adopted by the cell to overcome defects in LPS biogenesis.