THE ENVA PERMEABILITY CELL-DIVISION GENE OF ESCHERICHIA-COLI ENCODES THE 2ND ENZYME OF LIPID-A BIOSYNTHESIS - DP-3-O-(R-3-HYDROXYMYRISTOYL)-N--ACETYLGLUCOSAMINE DEACETYLASE

The envA gene of Escherichia coli has been shown previously to be esse ntial for cell viability (Beall, B. and Lutkenhaus, J. (1987) J. Bacte riol. 169, 5408-5415), yet it encodes a protein of unknown function. E xtracts of strains harboring the mutant envA1 allele display 3.5-18-fo ld reductions in UDP-3-O-acyl-N-acetylglucosamine deacetylase specific activity. The deacetylase is the second enzymatic step of lipid A bio synthesis. The structural gene coding for the deacetylase has not been as signed. In order to determine if the envA gene encodes the deacety lase, envA was cloned into an sopropyl-1-thio-beta-D-galactopyranoside -inducible T7-based expression system. Upon induction, a protein of th e size of envA was highly overproduced, as judged by SDS-PAGE. Direct deacetylase assays of cell lysates revealed a concomitant similar to 5 ,000-fold overproduction of activity. Assays of the purified, overprod uced EnvA protein demonstrated a further similar to 5-fold increase in specific activity. N-terminal amino acid sequencing of the purified p rotein showed that the first 20 amino acids matched the predicted envA nucleotide sequence. Contaminating species were present at less than 1% of the level of the EnvA protein. Thus, envA is the structural gene for UDP-3-O-acyl-GlcNAc deacetylase. Based on its function in lipid A biosynthesis, we propose the new designation lpxC for this gene.