Homology modeling and site-directed mutagenesis reveal catalytic key amino acids of 3beta-hydroxysteroid-dehydrogenase/C4-decarboxylase from Arabidopsis.

Sterols become functional only after removal of the two methyl groups at C4 by a membrane-bound multienzyme complex including a 3beta-hydroxysteroid-dehydrogenase/C4-decarboxylase (3betaHSD/D). We recently identified Arabidopsis (Arabidopsis thaliana) 3betaHSD/D as a bifunctional short-chain dehydrogenase/reductase protein. We made use of three-dimensional homology modeling to identify key amino acids involved in 4alpha-carboxy-sterol and NAD binding and catalysis.

The Nicotiana sylvestris extensin gene, Ext 1.2A, is expressed in the root transition zone and upon wounding.

The Ext 1.2A gene of Nicotiana sylvestris L. encoding an extensin, a cell wall structural protein, was characterized.