The galE gene of Pasteurella multocida has been isolated by complement
ing galE-defective mutants of Salmonella typhimurium with a plasmid li
brary of this organism. The complete nucleotide sequence of the P. mul
tocida galE gene consists of 1017 nucleotides, encoding a predicted po
lypeptide of 339 amino acids. The deduced amino acid sequence displaye
d the highest identity (85%) to the GalE protein of Haemophilus influe
nzae. However, the gene organization surrounding the galE locus was di
fferent from that of H. influenzae. A galE-defective mutant of P. mult
ocida was obtained by replacement of the active galE gene by a copy in
activated in vitro. The resulting galE mutant was highly attenuated as
seen in a biological test carried out in a mouse model.