Conservation of function between mammalian and plant steroid 5 alpha-reductases
1997
Li, J. | Biswas, M.G. | Chao, A. | Russell, D.W. | Chory, J.
Arabidopsis det2 mutants are small dark-green dwarfs displaying pleiotropic defects in light-regulated development during multiple stages of the plant life cycle. The DET2 gene encodes a protein that shares approximately 40% sequence identity with mammalian steroid 5 alpha-reductases and is implicated in the synthesis of a class of plant steroids, the brassinosteroids. Here we show that the DET2 protein, when expressed in human embryonic kidney 293 cells, catalyzes the 5 alpha-reduction of several animal steroid substrates and has similar kinetic properties to the mammalian steroid 5 alpha-reductase enzymes. Moreover, human steroid 5 alpha-reductases expressed in det2 mutant plants can substitute for DET2 in brassinosteroid biosynthesis. These data indicate that DET2 is an ortholog of the mammalian steroid 5 alpha-reductases and provide further evidence that brassinosteroids play an essential role in light-regulated plant development. The structural and functional conservation between DET2 and human steroid 5 alpha-reductases raise interesting issues concerning the evolutionary origin of the steroid hormone signaling system.
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