HEMIN BIOSYNTHESIS IN HAEMOPHILUS

Abstract

Hemin-independent Haemophilus species have been shown to form hemin by the classical hemin biosynthetic pathway. Three distinct species of Haemophilus [H. influenzae, H. aegyptus and H. canis (H. haemoglobinophilus)] all lost the enzymatic capacities to convert [delta]-aminolevulinic-acid to protoporphyrin which accounts for their dependence on hemin for growth. The strain of H. aegyptus tested cannot form hemin from protoporphyrin, can be transformed with deoxyribonucleic-acid (DNA) from H. influenzae and the resultant progeny have the enzymatic activity to convert protoporphyrin to hemin. Attempts to transform these species to hemin independence with DNA from hemin-independent H. parainfluenzae are unsuccessful under conditions where streptomycin resistance is readily transformed.