CHARACTERIZATION OF A NEW RUBREDOXIN ISOLATED FROM DESULFOVIBRIO-DESULFURICANS-27774 - DEFINITION OF A NEW FAMILY OF RUBREDOXINS

A new rubredoxin from the sulphate-reducing bacterium Desulfovibrio de sulfuvicans ATCC 27774, grown with nitrate as terminal electron accept or, was isolated and characterised, The protein is an 8.5 kDa monomer containing one iron atom per molecule, with a reduction potential of 2 5 +/- 5 mV at pH 7.6. Like the recombinant Rdl protein from D. vulgari s, expressed in Escherichia coli [Lumpio, H.L., Shenvi, N.V., Garg, R. P., Summers. A.O. and Kurtz, D.M., J. Bacteriol. 179 (1997) 4607-1615] , it contains an unusual spacing of four amino acids between the first two of the iron coordinating cysteinyl residues. This difference is r eflected in the structure of the iron centre, as observed by visible a nd EPR spectroscopies. All together, these features make these protein s the first members of a new family of rubredoxins. (C) 1998 Federatio n of European Biochemical Societies.