2v93
EQUILLIBRIUM MIXTURE OF OPEN AND PARTIALLY-CLOSED SPECIES IN THE APO STATE OF MALTODEXTRIN-BINDING PROTEIN BY PARAMAGNETIC RELAXATION ENHANCEMENT NMR
|
OverviewOverview
Large-scale domain rearrangements in proteins have long been recognized to, have a critical function in ligand binding and recognition, catalysis and, regulation. Crystal structures have provided a static picture of the apo, (usually open) and holo usually closed) states. The general question, arises as to whether the apo state exists as a single species in which the, closed state is energetically inaccessible and interdomain rearrangement, is induced by ligand or substrate binding, or whether the predominantly, open form already coexists in rapid equilibrium with a minor closed, species. The maltose-binding protein (MBP), a member of the bacterial, periplasmic binding protein family, provides a model system for, investigating this problem because it has been the subject of extensive, studies by crystallography, NMR and other biophysical techniques. Here we, show that although paramagnetic relaxation enhancement (PRE) data for the, sugar-bound form are consistent with the crystal structure of holo MBP, the PRE data for the apo state are indicative of a rapidly exchanging, mixture (ns to mus regime) of a predominantly ( approximately 95%) open, form (represented by the apo crystal structure) and a minor (approximately, 5%) partially closed species. Using ensemble simulated annealing, refinement against the PRE data we are able to determine a <r(-6)>, ensemble average structure of the minor apo species and show that it is, distinct from the sugar-bound state.
About this StructureAbout this Structure
2V93 is a Single protein structure of sequence from Escherichia coli with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Open-to-closed transition in apo maltose-binding protein observed by paramagnetic NMR., Tang C, Schwieters CD, Clore GM, Nature. 2007 Oct 25;449(7165):1078-82. PMID:17960247
Page seeded by OCA on Wed Jan 23 12:25:03 2008