CLONING AND EXPRESSION OF RAT CDNA-ENCODING CORTICOSTEROID 11-BETA-DEHYDROGENASE

  • 15 November 1989
    • journal article
    • research article
    • Vol. 264  (32) , 18939-18943
Abstract
Corticosteroid 11.beta.-dehydrogenase (11-DH) catalyzes the conversion of cortisol to the inactive metabolite cortisone. Absence of 11-DH activity leads to a potentially fatal form of childhood hypertension termed apparent mineralocorticoid excess. As a first step in elucidating the molecular basis of this disorder, we isolated and characterized a rat cDNA clone encoding 11-DH. This clone hybridized to a single mRNA species in liver, kidney, and testis RNA but not to RNA from heart. The insert was 1265 base pairs long and included an 861-base pair open reading frame encoding 287 amino acids. A search of sequence databases revealed that 11-DH is identical in about 27% of amino acid residues to ribitol dehydrogenase from Klebsiella and to the product of the nodG gene from the nitrogen-fixing bacterium, Rhizobium meliloti, thus defining a new superfamily of genes encoding dehydrogenases. The 11-DH cDNA was expressed by transfection into Chinese hamster ovary cells under the control of an SV40 promoter. The expressed enzyme mediated both 11.beta.-dehydrogenation and the reverse 11-oxoreduction reaction. Southern blot analysis of rat and human DNA suggested that additional genes related to 11-DH exist in both species.

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