Molecular basis of the amylose-like polymer formation catalyzed by Neisseria polysaccharea amylosucrase
Albenne, Cécile | Skov, Lars K. | Mirza, Osman | Gajhede, Michael | Feller, Georges | d'Amico, Salvino | André-Leroux, Gwenaëlle | Potocki Veronese, Gabrielle | van Der Veen, Bart A. | Monsan, Pierre | Remaud Simeon, Magali | Unité mixte de recherche biotechnologies bioprocédés ; Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse) ; Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS) | Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT) | Centre National de la Recherche Scientifique (CNRS) | Department of Medicinal Chemistry ; University of Copenhagen = Københavns Universitet (UCPH) | Université de Liège = University of Liège = Universiteit van Luik = Universität Lüttich (ULiège) | PhysicoChimie des Macromolécules (LPCM) ; Institut National de la Recherche Agronomique (INRA) | Institut National des Sciences Appliquées de Lyon (INSA Lyon) ; Université de Lyon-Institut National des Sciences Appliquées (INSA) | CRITT Génie des Procédés Technologies Environnementales (CRITT GPTE) ; Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse) ; Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3) ; Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP) ; Université de Toulouse (UT)
International audience
Показать больше [+] Меньше [-]Английский. Amylosucrase from Neisseria polysaccharea is a remarkable transglucosidase from family 13 of the glycoside-hydrolases that synthesizes an insoluble amylose-like polymer from sucrose in the absence of any primer. Amylosucrase shares strong structural similarities with alpha-amylases. Exactly how this enzyme catalyzes the formation of alpha-1,4-glucan and which structural features are involved in this unique functionality existing in family 13 are important questions still not fully answered. Here, we provide evidence that amylosucrase initializes polymer formation by releasing, through sucrose hydrolysis, a glucose molecule that is subsequently used as the first acceptor molecule. Maltooligosaccharides of increasing size were produced and successively elongated at their nonreducing ends until they reached a critical size and concentration, causing precipitation. The ability of amylosucrase to bind and to elongate maltooligosaccharides is notably due to the presence of key residues at the OB1 acceptor binding site that contribute strongly to the guidance (Arg415, subsite +4) and the correct positioning (Asp394 and Arg446, subsite +1) of acceptor molecules. On the other hand, Arg226 (subsites +2/+3) limits the binding of maltooligosaccharides, resulting in the accumulation of small products (G to G3) in the medium. A remarkable mutant (R226A), activated by the products it forms, was generated. It yields twice as much insoluble glucan as the wild-type enzyme and leads to the production of lower quantities of by-products.
Показать больше [+] Меньше [-]Библиографическая информация
Эту запись предоставил Institut national de la recherche agronomique