Aj. Else et al., DIHYDROLIPOAMIDE DEHYDROGENASE IN THE TRYPANOSOMA SUBGENUS, TRYPANOZOON, Molecular and biochemical parasitology, 64(2), 1994, pp. 233-239
The enzyme dihydrolipoamide dehydrogenase has been discovered and char
acterised in four salivarian trypanosomes of the subgenus trypanozoon:
Trypanosoma brucei brucei, T.b. gambiense, T.b. rhodesiense, and Tryp
anosoma evansi. The three T. brucei species, which have insect procycl
ic forms biochemically distinct from their mammalian bloodstream forms
, express dihydrolipoamide dehydrogenase in both cell types, but have
higher levels in the procyclic forms. Determination of Michaelis const
ants for the enzyme from each of the three T. brucei species did not r
eveal any significant kinetic differences between the bloodstream and
procyclic enzymes. On Western blots, antibodies raised against dihydro
lipoamide dehydrogenase from the stercorarian trypanosome, Trypanosoma
cruzi, cross-react strongly with the dihydrolipoamide dehydrogenase f
rom all three T. brucei species; by this method, the relative molecula
r masses of their dihydrolipoamide dehydrogenases are indistinguishabl
e. Dihydrolipoamide dehydrogenase was purified from bath the bloodstre
am and the procyclic forms of T.b. brucei, and the N-termini have been
sequenced. These sequences are identical to the derived protein seque
nce of the cloned gene (Else et al., fur. J. Biochem. 212 (1993) 423-4
29), but have a nine amino acid N-terminal truncation, giving an N-ter
minus equivalent to that of T. cruzi dihydrolipoamide dehydrogenase. T
he T.b. brucei dihydrolipoamide dehydrogenase gene has been expressed
in Escherichia coli and the resultant protein purified; its N-terminus
is processed in a similar fashion to that in the trypanosome, but wit
h reduced specificity.