Distinct physiological roles for the two l-asparaginase isozymes of Escherichia coli

- Escherichia coli contains two l-asparaginase isozymes with distinct localization, kinetics and regulation.
- Mutant strains were used to examine the roles of these enzymes in l-asparagine utilization.
- We report that l-asparaginase II permits growth on asparagine and glycerol under anaerobic conditions.
- We propose that this enzyme is the first step in a co-regulated pathway leading to fumarate.
- The pathway is regulated by anaerobiosis and cAMP and provides a terminal elector acceptor.