The Adenylosuccinate Synthetase from the Hyperthermophilic ArchaeonPyrococcusSpecies Displays Unusual Structural Features |
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| Affiliation: | 1. Institut de Génétique et Microbiologie, Bâtiment 409 URA 1354, Université Paris-Sud, 91405 Orsay Cedex, France;2. Laboratoire de Biotechnologie des Microorganismes Hydrothermaux, Département Environnement Profond, IFREMER, Centre de Brest, BP70, 29280 Plouzané, France;1. Department of Endocrinology, Fourth Hospital, Hebei Medical University, Shijiazhuang 050011, China;2. Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Department of Immunology, Hebei Medical University, Shijiazhuang 050017, China;3. Department of Medical Oncology, Bethune International Peace Hospital, Shijiazhuang 050082, China;4. Department of Medical Oncology, The First hospital of Shijiazhuang City, Shijiazhuang 050011, China;1. N.D Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia;2. D.K Zabolotny Insitute of Microbiology and Virology of the National Academy of Sciences, Kiev, Ukraine;3. Higher Chemical College of the Russian Academy of Sciences, D. I. Mendeleev University of Chemical Technology of Russia, Moscow, Russia;1. Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA;2. Basic Research Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA;3. Department of Biotechnology, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan;4. Department of Biological Chemistry, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan |
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| Abstract: | The first example of a hyperthermophilic adenylosuccinate synthetase is reported, which is an enzyme that must maintain its folded structure at temperatures as high as 102°C. The amino acid sequence of this key enzyme has been determined after cloning and sequencing thepurA-like gene from the archaealPyrococcussp. strain ST700. The corresponding protein displays two unexpected features: (1) it is 21% shorter than the homologous mesophilic enzymes and this shortening corresponds to the loss of two α-helices and three β-strands present in theEscherichia colienzyme; (2) surprisingly, the archaeal adenylosuccinate synthetase has a significant number of substitutions in residues that are conserved in all other homologous enzymes from bacteria to man. InE. coli, the conserved residues have been described as essential for catalytic activity and/or for maintaining the folded structure of the homodimer. Despite these drastic differences, thepurA-like archaeal gene seems to be normally expressed and its product functionsin vivoin bacteria, since it complemented anE. coli purAauxotroph. The archaeal adenylosuccinate synthetase appears to be a good example of abona fideorthologous protein. Reconstruction of phylogenetic trees showed that the archaeal gene is equally distantly related to both eukaryotes and bacteria, independently of the numerous substitutions observed at critical positions. |
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