Two genes involved in the 1,3-diaminopropane production pathway in Haemophilus influenzae

Abstract

We previously cloned and sequenced the Acinetobacter baumannii dat and ddc genes encoding L-2,4-diaminobutyrate: 2-ketoglutarate 4-aminotransferase (DABA AT) and DABA decarboxylase, respectively, involved in the 1,3-diaminopropane (DAP) production pathway. Homology searches of the gene products provided an indication that a similar gene cluster is present in the genome of Haemophilus influenzae Rd. This was first verified by detection of the corresponding enzyme activities in and the production of DAP by all H. influenzae strains examined. Both of the crude enzymes from the representative strain of H. influenzae showed catalytic properties essentially similar to the A. baumannii DABA AT and DABA DC. An Escherichia coli clone carrying the dat homolog of H. influenzae Rd showed a high level of DABA AT activity, the enzyme protein responsible being detected by immunoblot analysis. These results specify the two H. influenzae genes involved in DAP production.