L-asparaginase II of Escherichia coli K-12: cloning, mapping and sequencing of the ansB gene.

The Escherichia coli gene ansB, encoding the chemotherapeutic enzyme L-asparaginase II, has been cloned, using a strategy based on the polymerase chain reaction, and sequenced. The amino acid (aa) sequence differs in eleven positions from the data previously derived by direct aa sequencing. A cleavable secretory signal peptide precedes the N terminus of the mature protein. The ansB gene maps to position 3114 kb on the physical map of E. coli [Kohara et al., Cell 50 (1987) 495-508], corresponding to approx. 63.8 min on the genetic map.