Effect of lipopolysaccharide mutation on oxygenation of linoleic acid by recombinant Escherichia coli expressing CYP102A2 of Bacillus subtilis

The effects of cell wall mutation on the oxygenation of linoleic acid (M.W. 280) by recombinant Escherichia coli expressing the CYP102A2 gene encoding self-sufficient P450 monooxygenase of Bacillus subtilis was investigated. After the CYP102A2 gene was heterologously expressed in E. coli W3110 and its isogenic lipopolysaccharide (LPS) structural mutant strains, their whole-cell biotransformation activities were compared. The mutants used in this study had previously been designated as MLK53, MLK1067, and MLK986. These strains carry one or two defined mutations in the secondary acyl fatty acids of the LPS lipid A constituent. The CYP102A2 gene was overexpressed in both wild type E. coli W3110 and its mutant strains, with the specific activity ranging from 1.7 to 2.1 U/mg protein. Interestingly, the whole-cell biotransformation activity of those recombinant biocatalysts differed significantly. Indeed, MLK986 possessing the tetraacylated LPS showed a higher oxygenation activity of linoleic acid than those in wild type or other mutant strains having hexa-or penta-acylated LPSs. These results suggest that the biotransformation efficiency of E. coli-based biocatalysts, especially for medium-to large-sized lipophilic organic substrates, can be enhanced via engineering their LPS, which is known to function as a formidable barrier for hydrophobic molecules.