Premium
Allosteric Activation and Dynamics of the ADP‐glucose Pyrophosphorylase from Escherichia coli
Author(s) -
Bharani Krishna L.,
Tasch Joseph,
Figueroa Carlos M.,
Mahaffey Angela,
Iglesias Alberto Alvaro,
Olsen Ken W.,
Ballicora Miguel Angel
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.lb63
Subject(s) - allosteric regulation , escherichia coli , enzyme , biochemistry , allosteric enzyme , residue (chemistry) , mutagenesis , chemistry , substrate (aquarium) , active site , biophysics , binding site , transferase , molecular dynamics , protein dynamics , enzyme activator , site directed mutagenesis , stereochemistry , protein structure , biology , mutation , gene , mutant , ecology , computational chemistry
ADP‐glucose pyrophosphorylase is the enzyme responsible for the regulation of the synthesis of bacterial glycogen and starch in plants and is regulated by a variety of metabolites in different organisms. We show that two conserved residues are critical for triggering the activation. Molecular modeling of the Escherichia coli enzyme showed that binding of the substrate ATP correlates with conformational changes of two loops, going from an open to a closed form. Two highly conserved residues in these two loops, Trp 113 and Gln 74 , are involved in a network of hydrogen bonds only present in the substrate‐bound form. Without disrupting the binding of activators, site‐directed mutagenesis of Trp 113 or Gln 74 turned the enzyme insensitive to activation, via interrupting the communication between the regulatory site and the active site. Molecular dynamics shown that mutations in the Trp residue cause a dramatic effect in the mobility of the surrounding residues, strongly suggesting that precise orientation of this loop is critical to trigger the allosteric effect. Supported by NSF grant MCB 1024945, CONICET (PIP 2519), DFI Fellowship, and Carbon and Mulcahy Scholarship (Loyola University)