THE IMPACT WHICH PROTEIN Z AND HORDEIN POLYPEPTIDES HAVE ON THE NUTRITIONAL VALUE OF THE GRAIN MAKES IT IMPERATIVE TO ELUCIDATE THE MOLECULAR STRUCTURE OF THE PAZ 1,HOR 1, HOR 2, HOR 3 LOCI AND THEIR REGULATION. KNOWLEDGE OF THE ORGANIZATION OF THESE GENES IS A PREREQUISITE FOR BREEDING MALT- AND FEED-BARLEY OF IMPROVED QUALITY BY GENETIC ENGINEERGING.
Research has been carried out to determine regions in the enzyme of barley grain that can be altered to yield a more heat stable enzyme as the high temperatures applied during kilning and mashing of the germinated grain destroy the barley enzyme which degrades the cell walls of the dead endosperm.
The structure and expression of genes encoding storage proteins were determined and a molecular map of a chromosome region encoding about 20 storage proteins was established. The synthesis and deposition of storage proteins in the endosperm cell were elucidated and a nondestructive immunological method for recognizing individual proteins in the grain was developed. This method enables selection of grains with elevated or reduced amounts of single proteins.
By introducing a barley gene encoding the cell wall degrading enzyme into yeast, strains secreting the enzyme were identified. The culture media in which the yeast strains grow served as a convenient source of the enzyme. Engineering different Bacillus genes encoding a cell wall degrading enzyme demonstrated that it is possible to alter the structure of the enzyme to a more heat stable form.
HORDEIN, THE MAJOR GROUP OF STORAGE PROTEINS IN THE BARLEY ENDOSPERM, IS CODED FOR BY 3 DIFFERENT LOCI ON CHROMOSOME 5. HORDEIN POLYPEPTIDES ARE LOW IN THE ESSENTIAL AMINO ACIDS, AND THEIR SYNTHESIS IN LARGE AMOUNTS DURING GRAIN FILLIN ACCOUNTS FOR THE LOW PROTEIN QUALITY OF BARLEY WHEN FED TO MONOGASTRIC ANIMALS. PROTEIN Z, THE MAJOR LYSIN-RICH ENDOSPERM ALBUMIN, IS CODED FOR BY THE PAZ 1 LOCUS ON CHROMOSOME 4.
CDNAS ENCODING HORDEIN POLYPEPTIDES AND PROTEIN Z HAVE BEEN OBTAINED AND THEIR NUCLEOTIDE SEQUENCE DETERMINED. USING THESE CDNAS AS TOOLS, THE MOLECULAR ORGANIZATION OF THE GENE COMPLEXES SPECIFYING HORDEIN POLYPEPTIDES AND THE SINGLE GENE CODING FOR PROTEIN Z IS TO BE ESTABLISHED.
Funding SchemeCSC - Cost-sharing contracts