Aromatic amino acid insensitive DAHP synthases
Abstract
The characterization of two aromatic amino acid insensitive DAHP synthases is described; one from E. coli, and one from potato. In E. coli, there are three DAHP synthase isozymes; the activity of each isozyme is feedback inhibited by one of the aromatic amino acids. The cloning and nucleotide sequence characterization of a tyrosine insensitive DAHP synthase isozyme from E. coli is described. In Solanum tuberosum L. (potato), there are multiple isozymes of DAHP synthase; none are inhibited by the aromatic amino acids. A cDNA encoding DAHP synthase from potato suspension culture cells was expressed in E. coli; the potato DAHP synthase complements E. coli DAHP synthase mutants. The potato DAHP synthase was purified from extracts of E. coli and partially characterized. Antibodies against the E. coli expressed potato DAHP synthase were prepared; these antibodies recognize DAHP synthase in a number of plants and potato organs. However, DAHP synthases of potato organs are recognized differently by anti-cDNA encoded DAHP synthase and anti-tuber DAHP synthase antibodies. This antigenic dissimilarity indicates the tuber DAHP synthase antibodies. This antigenic dissimilarity indicates the tuber DAHP synthases I and the cDNA encoded DAHP synthase II are isozymes. A 6 kb fragment containing potato genomic DNA upstream of the coding region for isozyme II was isolated. 1.3 kb of DNA containing the promoter region of the gene encoding DAHP synthase II was characterized through nucleotide sequence analysis, and the transcript start sites were determined.
Degree
Ph.D.
Advisors
Herrmann, Purdue University.
Subject Area
Biochemistry|Molecular biology
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