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Article Dans Une Revue Biochemical Journal Année : 2007

Novel class of glutathione transferases from cyanobacteria exhibit high catalytic activities towards naturally occurring isothiocyanates

Eric Wiktelius
  • Fonction : Auteur

Résumé

A novel class of glutathione transferases, called the Chi class, originating from cyanobacteria and with properties not observed previously in prokaryotic enzymes is presented. Glutathione transferases constitute a widespread multifunctional group of proteins, of which mammalian enzymes are the best characterised. Although glutathione transferases have their origin in prokaryotes, few bacterial representatives have been characterised in detail, and the catalytic activities and substrate specificities observed have generally been very modest. The few well-studied bacterial glutathione transferases have largely unknown physiological functions. Genome databases reveal that cyanobacteria have an extensive arsenal of glutathione-associated proteins. This paper reports on two cyanobacterial glutathione transferases which are the first examples of bacterial enzymes that are as catalytically efficient as the best mammalian enzymes. Glutathione transferases from the thermophile Thermosynechococcus elongatus BP-1 and from Synechococcus elongatus PCC 6301 were found to catalyse the conjugation of naturally occurring plant-derived isothiocyanates to glutathione at high rates. The cyanobacterial glutathione transferases studied are smaller than previously described members of this enzyme family, but display many of the typical structural features characteristics of glutathione transferases. They are also active towards several classical substrates, but at the same moderate rates that have been observed for other glutathione transferases derived from prokaryotes. The cloning, expression and characterisation of two cyanobacterial glutathione transferases are described. The possible significance of the observed catalytic properties is discussed in the context of physiological relevance and glutathione transferase evolution.

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Dates et versions

hal-00478770 , version 1 (30-04-2010)

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Eric Wiktelius, Gun Stenberg. Novel class of glutathione transferases from cyanobacteria exhibit high catalytic activities towards naturally occurring isothiocyanates. Biochemical Journal, 2007, 406 (1), pp.115-123. ⟨10.1042/BJ20070328⟩. ⟨hal-00478770⟩

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