Differentiation-inducing-factor dechlorinase, a novel cytosolic dechlorinating enzyme from Dictyostelium discoideum

Nayler, O., Insall, R. and Kay, R. R. (1992) Differentiation-inducing-factor dechlorinase, a novel cytosolic dechlorinating enzyme from Dictyostelium discoideum. European Journal of Biochemistry, 208(2), pp. 531-536. (doi:10.1111/j.1432-1033.1992.tb17217.x) (PMID:1521542)

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Differentiation-inducing-factor 1 (DIF-1) is a dichlorinated alkyl phenone {1-[(3,5-dichloro-2,6-dihydroxy-4-methoxy)phenyl]hexan-1-one} from Dictyostelium discoideum, that induces amoebae to differentiate into stalk cells. It was shown previously that DIF-1 is rapidly metabolized into a series of more polar compounds by living cells [Traynor, D. & Kay, R. R. (1991) J. Biol. Chem. 266, 5291–5297]. The first step in DIF-1 metabolism is the formation of DIF metabolite 1 (now known to be DIF-3) by a monodechlorination. We report here the discovery of the enzyme activity catalyzing this dechlorination. A very sensitive enzyme assay was developed, using [3H]DIF-1 and a TLC system to separate DIF-1 from the product, DIF-3. DIF-1 3(5)-dechlorinase is present in the high-speed supernatant of cell lysates, and uses glutathione, at physiological concentrations, as cofactor. Kinetic measurements indicate a Km for DIF-1 of about 70 nM. The enzyme activity is inhibited by DIF-2 (the pentan-1-one analogue of DIF-1), with a median inhibitor concentration (IC50) of 1 μM, and DIF-3 (IC50= 5 μM), which presumably act as substrates, but other compounds structurally related to DIF-1 were much less effective. Aurothioglucose, an inhibitor of selenocysteine enzymes, inhibited DIF-1 3(5)-dechlorinase with IC50= 100 nM. DIF-1 3(5)-dechlorinase activity is developmentally regulated. It is essentially absent from growing cells and increases at the end of aggregation to reach a first peak of activity at the first finger stage, with a further rise at culmination.

Item Type:Articles
Glasgow Author(s) Enlighten ID:UNSPECIFIED
Authors: Nayler, O., Insall, R., and Kay, R. R.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cancer Sciences
Journal Name:European Journal of Biochemistry
ISSN (Online):1432-1033
Published Online:03 March 2005

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