Molecular cloning and expression of a locus (mdoA) implicated in the biosynthesis of membrane‐derived oligosaccharides in Escherichia coli

Abstract
Summary: Mutants of Escherichia coli defective in the mdoA locus are blocked at an early stage in the biosynthesis of membrane‐derived oligosaccharides. The mdoA locus has now been cloned into multicopy plasmids. A 5kb DNA fragment is necessary to complement mdoA mutations. Cells harbouring the mdoA+ plasmid produced three to four times more MDO than wild‐type cells. MDO overproduction did not affect the degree of MDO substitution with sn‐1‐phosphoglycerol residues. The biosynthesis of MDO remained under osmotic control in overproducing strains.