1wcr
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TRIMERIC STRUCTURE OF THE ENZYME IIA FROM ESCHERICHIA COLI PHOSPHOTRANSFERASE SYSTEM SPECIFIC FOR N,N'-DIACETYLCHITOBIOSE
OverviewOverview
The solution structure of trimeric Escherichia coli enzyme IIA(Chb) (34, kDa), a component of the N,N'-diacetylchitobiose/lactose branch of the, phosphotransferase signal transduction system, has been determined by NMR, spectroscopy. Backbone residual dipolar couplings were used to provide, long range orientational restraints, and long range (|i - j| > or = 5, residues) nuclear Overhauser enhancement restraints were derived, exclusively from samples in which at least one subunit was, 15N/13C/2H/(Val-Leu-Ile)-methyl-protonated. Each subunit consists of a, three-helix bundle. Hydrophobic residues lining helix 3 of each subunit, are largely responsible for the formation of a parallel coiled-coil, trimer. The active site histidines (His-89 from each subunit) are located, in three symmetrically placed deep crevices located at the interface of, two adjacent subunits (A and C, C and B, and B and A). Partially shielded, from bulk solvent, structural modeling suggests that phosphorylated His-89, is stabilized by electrostatic interactions with the side chains of His-93, from the same subunit and Gln-91 from the adjacent subunit. Comparison, with the x-ray structure of Lactobacillus lactis IIA(Lac) reveals some, substantial structural differences, particularly in regard to helix 3, which exhibits a 40 degrees kink in IIA(Lac) versus a 7 degrees bend in, IIA(Chb). This is associated with the presence of an unusually large, (230-angstroms3) buried hydrophobic cavity at the trimer interface in, IIA(Lac) that is reduced to only 45 angstroms3) in IIA(Chb).
About this StructureAbout this Structure
1WCR is a Single protein structure of sequence from Escherichia coli. Active as Protein-N(pi)-phosphohistidine--sugar phosphotransferase, with EC number 2.7.1.69 Full crystallographic information is available from OCA.
ReferenceReference
Solution structure of enzyme IIA(Chitobiose) from the N,N'-diacetylchitobiose branch of the Escherichia coli phosphotransferase system., Tang C, Williams DC Jr, Ghirlando R, Clore GM, J Biol Chem. 2005 Mar 25;280(12):11770-80. Epub 2005 Jan 14. PMID:15654077
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