ADPglucose pyrophosphorylase's N-terminus: Structural role in allosteric regulation

• Autores: Bejar, C.M.; Ballicora, M.A.; Iglesias, Alberto Alvaro; Preiss, J.
• Año de publicación: 2006
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: ADPGLUCOSE PYROPHOSPHORYLASE; ALLOSTERIC REGULATION; GLYCOGEN SYNTHESIS; N-TERMINUS DELETION
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We studied the functional role of the Escherichia coli ADPglucose pyrophosphorylase's N-terminus in allosteric regulation, and the particular effects caused by its length. Small truncated mutants were designed, and those lacking up to 15-residues were active and highly purified for further kinetic analyses. NΔ3 and NΔ7 did not change the kinetic parameters with respect to the wild-type. NΔ11 and NΔ15 enzymes were insensitive to allosteric regulation and highly active in the absence of the activator. Co-expression of two polypeptides corresponding to the N- and C-termini generated an enzyme with activation properties lower than those of the wild-type [C.M. Bejar, M.A. Ballicora, D.F. Gómez Casati, A.A. Iglesias, J. Preiss, The ADPglucose pyrophosphorylase from Escherichia coli comprises two tightly bound distinct domains, FEBS Lett. 573 (2004) 99-104]. Here, we characterized a NΔ15 co-expression mutant, in which the allosteric regulation was restored to wild-type levels. Unusual allosteric effects caused by either an N-terminal truncation or co-expression of individual domains may respond to structural changes favoring an up-regulated or a down-regulated conformation rather than specific activator or inhibitor sites' disruption.
Fil: Bejar, C.M.. Michigan State University; Estados Unidos
Fil: Ballicora, M.A.. Loyola University Of Chicago; . Michigan State University; Estados Unidos
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: Preiss, J.. Michigan State University; Estados Unidos