title: A specific beta-glucosidase-aggregating factor is responsible for the beta-glucosidase null phenotype in maize.
abstract: Maize (Zea mays L.) beta-glucosidase was extracted from shoots of a wild-type (K55) and a "null" (H95) maize genotype. Enzyme activity assays and electrophoretic data showed that extracts from the null genotype had about 10% of the activity present in the normal genotype. Zymograms of the null genotype were devoid of any activity bands in the resolving gel, but had a smeared zone of activity in the stacking gel after native polyacrylamide gel electrophoresis. When extracts were made with buffers containing 0.5% to 2% sodium dodecyl sulfate, the smeared activity zone entered the resolving gel as a distinct band. These data indicated that the null genotypes have beta-glucosidase activity, but the enzyme occurs as insoluble or poorly soluble large quaternary complexes mediated by a beta-glucosidase-aggregating factor (BGAF). BGAF is a 35-kD protein and binds specifically to beta-glucosidase and renders it insoluble during extraction. BGAF also precipitates beta-glucosidase that is added exogenously to supernatant fluids of the null tissue extracts. The specific beta-glucosidase-aggregating activity of BGAF is unequivocally demonstrated. These data clearly show that the monogenic inheritance reported for the null alleles at the beta-glucosidase gene is actually for the BGAF protein, and BGAF is solely responsible for beta-glucosidase aggregation and insolubility and, thus, the apparent null phenotype.
authors.affiliation: Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060-0406, USA. aevatan@vt.edu
authors.forename: A
authors.initials: A
authors.lastname: Esen
authors.forename: D J
authors.initials: DJ
authors.lastname: Blanchard
mesh_terms: D010641:Phenotype; D003313:Zea mays / Q000201:enzymology / Q000235:genetics*; D001617:beta-Glucosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D001617:beta-Glucosidase