Cloning and constitutive expression of the N-acetylneuraminate lyase gene of Escherichia coli.

The N-acetylneuraminate (NANA) lyase (EC 4.1.3.3) gene from Escherichia coli was self-cloned in E. coli. Transformants were selected by complementation of a NANA lyase-deficient E. coli strain. One clone was found to produce NANA lyase, and it contained a recombinant plasmid, pNAL1, with a 9.0-kilobase HindIII insert. The cloning of the NANA lyase gene resulted in the change from inducible to constitutive production of the enzyme. The level of expression of the NANA lyase gene in E. coli(pNAL1) clones was two- to three-fold higher than that in the fully induced wild-type strains.