Long and Medium-Term Research: Studies on the Active Site of the Unique Aspartate Transcarbamoylase from the Soil Bacterium, Pseudomonas Aeruginosa This award is under the Long and Medium-Term Research at Foreign Centers of Excellence Program, which enables U.S. scientists and engineers to conduct three to twelve months of research abroad at research centers of proven excellence. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twelve-month postdoctoral research visit by Dr. John F. Vickrey of the University of North Texas to work with Dr. Guy Herve at the Centre National de la Recherche Scientifique (CNRS). Aspartate transcarbamoylase (ATcase, EC 2.1.3.2) is a pivotal enzyme in the pyrimidine biosynthetic pathway. In Escherichia coli, this regulatory polypeptide has the unique architecture which allows the enzyme to demonstrate allosteric response to the end products CTP and the parallel pathway ATP. This enzyme in prokaryotes has been divided into three classes, which are based upon regulatory response, subunit design and molecular weight. Until recently, the Pseudomonads were believed to contain the Class A ATCase which is the largest molecular weight enzyme (Mr360,000) and is composed of two tentative identical subunits. This project involves identifying the amino acid residues essential to the constitution of the catalytic center in this unique ATCase from P. aeruginosa. The award recommendation provides funds to cover international travel and a stipend for twelve months.
