Function of the htrB high temperature requirement gene of Escherichia coli in the acylation of lipid A: HtrB catalyzed incorporation of laurate

J Biol Chem. 1996 May 17;271(20):12095-102. doi: 10.1074/jbc.271.20.12095.


By assaying lysates of Escherichia coli generated with the hybrid lambda bacteriophages of an ordered library (Kohara, Y., Akiyama, K., and Isono, K. (1987) Cell 50, 495-508), we identified two clones (lambda232 and lambda233) capable of overexpressing the lauroyl transferase that functions after 3-deoxy-D-manno-octulosonic acid (Kdo) addition in lipid A biosynthesis (Brozek, K. A., and Raetz, C. R. H. (1990) J. Biol. Chem. 265, 15410-15417). The E. coli DNA inserts in lambda232 and lambda233 suggested that a known gene (htrB) required for rapid growth above 33 degrees C might encode the lauroyl transferase. Using the intermediate (Kdo)2-lipid IVA as the laurate acceptor, extracts of strains with transposon insertions in htrB were found to contain no lauroyl transferase activity. Cells harboring hybrid htrB+ plasmids overproduced transferase activity 100-200-fold. The overproduced transferase was solubilized with a non-ionic detergent and purified further by DEAE-Sepharose chromatography. With lauroyl acyl carrier protein as the donor, the purified enzyme rapidly incorporated one laurate residue into (Kdo)2-lipid IVA. The rate of laurate incorporation was reduced by several orders of magnitude when either one or both Kdos were absent in the acceptor. With a matched set of acyl-acyl carrier proteins, the enzyme incorporated laurate 3-8 times faster than decanoate or myristate, respectively. Transfer of palmitate, palmitoleate, or R-3-hydroxymyristate was very slow. Taken together with previous studies, our findings indicate that htrB encodes a key, late functioning acyltransferase of lipid A biosynthesis.

Publication types

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

MeSH terms

  • Acylation
  • Acyltransferases / biosynthesis
  • Acyltransferases / chemistry
  • Acyltransferases / genetics*
  • Acyltransferases / isolation & purification
  • Bacterial Proteins*
  • Bacteriophage lambda / genetics
  • Enzyme Stability
  • Escherichia coli / genetics*
  • Escherichia coli Proteins*
  • Genes, Bacterial*
  • Lauric Acids / metabolism*
  • Lipid A / biosynthesis*


  • Bacterial Proteins
  • Escherichia coli Proteins
  • Lauric Acids
  • Lipid A
  • lauric acid
  • Acyltransferases
  • LpxL protein, E coli
  • LpxL protein, bacteria