Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/11/2002
Publication Date: N/A
Technical Abstract: The nutritional quality of soybean (Glycline max [L.] Merr.), as human and animal feed, is often limited by a low amount of sulfur-rich amino acids, cysteine and methionine. We are interested in improving the sulfur amino acid content of soybean proteins by manipulating the enzymes involved in sulfur metabolism. The initial reduction of the activated form of sulfate, adenosine phosphate sulfate (APS), is mediated by APS reductase (E.C.452450). By screening a soybean seedling cDNA library with a 32P-labelled EST, we isolated three APS reductase clones. Nucleotide sequence analysis of these clones indicated that one of them contained the entire coding region (1414 bp) and encoded a 51.9 kD protein. We have investigated the expression of the APS reductase gene during seed development and in response to nutrient stress. We have also overexpressed soybean APS reductase in Escherichia coli and purified the protein by affinity chromatography. Western blot analysis using antibodies raised against the recombinant APS reductase showed that this protein accumulated during early stages and declined gradually during the later stages of seed development. We have also isolated a genomic clone by screening a cosmid library with radiolabeled APS reductase cDNA clone. The gene has four introns interspersed between the exons. Southern blot analysis indicated that a small gene family encoded APS reductase in soybeans.