1vkr
STRUCTURE OF IIB DOMAIN OF THE MANNITOL-SPECIFIC PERMEASE ENZYME II
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OverviewOverview
The solution structure of the cytoplasmic B domain of the mannitol (Mtl), transporter (II(Mtl)) from the mannitol branch of the Escherichia coli, phosphotransferase system has been solved by multidimensional NMR, spectroscopy with extensive use of residual dipolar couplings. The ordered, IIB(Mtl) domain (residues 375-471 of II(Mtl)) consists of a four-stranded, parallel beta-sheet flanked by two helices (alpha(1) and alpha(3)) on one, face and helix alpha(2) on the opposite face with a characteristic, Rossmann fold comprising two right-handed beta(1)alpha(1)beta(2) and, beta(3)alpha(2)beta(4) motifs. The active site loop is structurally very, similar to that of the eukaryotic protein tyrosine phosphatases, with the, active site cysteine (Cys-384) primed in the thiolate state (pK(a) < 5.6), for nucleophilic attack at the phosphorylated histidine (His-554) of the, IIA(Mtl) domain through stabilization by hydrogen bonding interactions, with neighboring backbone amide groups at positions i + 2/3/4 from Cys-384, and with the hydroxyl group of Ser-391 at position i + 7. Modeling of the, phosphorylated state of IIB(Mtl) suggests that the phosphoryl group can be, readily stabilized by hydrogen bonding interactions with backbone amides, in the i + 2/4/5/6/7 positions as well as with the hydroxyl group of, Ser390 at position i + 6. Despite the absence of any significant sequence, identity, the structure of IIB(Mtl) is remarkably similar to the, structures of bovine protein tyrosine phosphatase (which contains two long, insertions relative to IIB(Mtl)) and the cytoplasmic B component of enzyme, II(Chb), which fulfills an analogous role to IIB(Mtl) in the, N,N'-diacetylchitobiose branch of the phosphotransferase system. All three, proteins utilize a cysteine residue in the nucleophilic attack of a, phosphoryl group covalently bound to another protein.
About this StructureAbout this Structure
1VKR is a Single protein structure of sequence from Escherichia coli o127:h6. Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional solution structure of the cytoplasmic B domain of the mannitol transporter IImannitol of the Escherichia coli phosphotransferase system., Legler PM, Cai M, Peterkofsky A, Clore GM, J Biol Chem. 2004 Sep 10;279(37):39115-21. Epub 2004 Jul 15. PMID:15258141
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