Understanding the allosteric trigger for the fructose-1,6-bisphosphate regulation of the ADP-glucose pyrophosphorylase from Escherichia coli
| Autor: | Ana L. Bertolo, Ana María Magdalena Demonte, Carlos Maria Figueroa, Miguel A. Ballicora, Mabel Cristina Aleanzi, María Cecilia Esper, Alberto A. Iglesias |
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| Rok vydání: | 2011 |
| Předmět: |
Models
Molecular ACTIVATION SIGNAL PROPAGATION Fructose 1 6-bisphosphate Otras Ciencias Biológicas Allosteric regulation Regulatory site Glucose-1-Phosphate Adenylyltransferase Biochemistry Ciencias Biológicas chemistry.chemical_compound Enzyme activator Allosteric Regulation Escherichia coli Fructosediphosphates Glycogen synthase chemistry.chemical_classification ALLOSTERIC MECHANISM biology Activator (genetics) ADP-GLUCOSE PYROPHOSPHORYLASE Electrophoresis Capillary General Medicine GLYCOGEN/STARCH METABOLISM Enzyme chemistry Allosteric enzyme biology.protein Mutagenesis Site-Directed REGULATION DYNAMICS CIENCIAS NATURALES Y EXACTAS |
| Zdroj: | Biochimie. 93(10) |
| ISSN: | 1638-6183 |
| Popis: | ADP-glucose pyrophosphorylase is the enzyme responsible for the regulation of glycogen synthesis in bacteria. The enzyme N-terminal domain has a Rossmann-like fold with three neighbor loops facing the substrate ATP. In the Escherichia coli enzyme, one of those loops also faces the regulatory site containing Lys 39, a residue involved in binding of the allosteric activator fructose-1,6-bisphosphate and its analog pyridoxal-phosphate. The other two loops contain Trp 113 and Gln 74, respectively, which are highly conserved among all the ADP-glucose pyrophosphorylases. Molecular modeling of the E. coli enzyme showed that binding of ATP correlates with conformational changes of the latter two loops, going from an open to a closed (substrate-bound) form. Alanine mutants of Trp 113 or Gln 74 did not change apparent affinities for the substrates, but they became insensitive to activation by fructose-1,6-bisphosphate. By capillary electrophoresis we found that the mutant enzymes still bind fructose-1,6- bisphosphate, with similar affinity as the wild type enzyme. Since the mutations did not alter binding of the activator, they must have disrupted the communication between the regulatory and the substrate sites. This agrees with a regulatory mechanism where the interaction with the allosteric activator triggers conformational changes at the level of loops containing residues Trp 113 and Gln 74. Fil: Figueroa, Carlos Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina. Loyola University Chicago; Estados Unidos Fil: Esper, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Bertolo, Ana. Cornell University; Estados Unidos Fil: Demonte, Ana María Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Aleanzi, Mabel Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Iglesias, Alberto Alvaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; Argentina Fil: Ballicora, Miguel A.. Loyola University Chicago; Estados Unidos |
| Databáze: | OpenAIRE |
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