HETEROLOGOUS EXPRESSION OF CDNAS ENCODING BARLEY (HORDEUM-VULGARE) (1-]3)-BETA-GLUCANASE ISOENZYME GV

Two cDNAs have been isolated from libraries generated from poly(A)(+)R NA of young barley roots and leaves, using a cDNA encoding barley (1 - -> 3)-beta-glucanase isoenzyme GII as a probe. Nucleotide sequence ana lyses and ribonuclease protection assays show that the two cDNAs diffe r only in the length of their 3'-untranslated regions; the correspondi ng mRNAs are likely to originate from a single gene by tissue-specific processing at separate polyadenylation sites. When the coding region of the cDNA is expressed in E. coli, the resultant protein catalyses t he hydrolysis of (1 --> 3)-beta-glucan with an action pattern characte ristic of a (1 --> 3)-beta-glucan endohydrolase (EC 3.2.1.39). The enz yme has been designated isoenzyme GV of the barley (1 --> 3)-beta-gluc anase family.