Balanced biosynthesis of major membrane components through regulated degradation of the committed enzyme of lipid A biosynthesis by the AAA protease FtsH (HflB) in Escherichia coli

Mol Microbiol. 1999 Feb;31(3):833-44. doi: 10.1046/j.1365-2958.1999.01221.x.


The suppressor mutation, named sfhC21, that allows Escherichia coli ftsH null mutant cells to survive was found to be an allele of fabZ encoding R-3-hydroxyacyl-ACP dehydrase, involved in a key step of fatty acid biosynthesis, and appears to upregulate the dehydrase. The ftsH1(Ts) mutation increased the amount of lipopolysaccharide at 42 degrees C. This was accompanied by a dramatic increase in the amount of UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase [the IpxC (envA) gene product] involved in the committed step of lipid A biosynthesis. Pulse-chase experiments and in vitro assays with purified components showed that FtsH, the AAA-type membrane-bound metalloprotease, degrades the deacetylase. Genetic evidence also indicated that the FtsH protease activity for the deacetylase might be affected when acyl-ACP pools were altered. The biosynthesis of phospholipids and the lipid A moiety of lipopolysaccharide, both of which derive their fatty acyl chains from the same R-3-hydroxyacyl-ACP pool, is regulated by FtsH.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Dependent Proteases
  • Amidohydrolases / analysis
  • Amidohydrolases / physiology
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / physiology*
  • Blotting, Western
  • Cell Membrane / ultrastructure
  • Escherichia coli / enzymology*
  • Escherichia coli Proteins
  • Gene Expression Regulation, Bacterial*
  • Genotype
  • Lipid A / biosynthesis*
  • Lipopolysaccharides / analysis
  • Membrane Proteins / genetics*
  • Membrane Proteins / physiology*
  • Microscopy, Electron
  • Models, Biological
  • Mutagenesis
  • Phenotype
  • Precipitin Tests
  • Temperature
  • Time Factors


  • Bacterial Proteins
  • Escherichia coli Proteins
  • Lipid A
  • Lipopolysaccharides
  • Membrane Proteins
  • ATP-Dependent Proteases
  • FtsH protein, E coli
  • Amidohydrolases
  • UDP-3-O-acyl-N-acetylglucosamine deacetylase