Solution structure of the phosphoryl transfer complex between the cytoplasmic A domain of the mannitol transporter IIMannitol and HPr of the Escherichia coli phosphotransferase system.
The solution structure of the complex between the cytoplasmic A domain (IIA(Mtl)) of the mannitol transporter II(Mannitol) and the histidine-containing phosphocarrier protein (HPr) of the Escherichia coli phosphotransferase system has been solved by NMR, including the use of conjoined rigid body/torsion angle dynamics, and residual dipolar couplings, coupled with cross-validation, to permit accurate orientation of the two proteins. A convex surface on HPr, formed by helices 1 and 2, interacts with a complementary concave depression on the surface of IIA(Mtl) formed by helix 3, portions of helices 2 and 4, and beta-strands 2 and 3. The majority of intermolecular contacts are hydrophobic, with a small number of electrostatic interactions at the periphery of the interface. The active site histidines, His-15 of HPr and His-65 of IIA(Mtl), are in close spatial proximity, and a pentacoordinate phosphoryl transition state can be readily accommodated with no change in protein-protein orientation and only minimal perturbations of the backbone immediately adjacent to the histidines. Comparison with two previously solved structures of complexes of HPr with partner proteins of the phosphotransferase system, the N-terminal domain of enzyme I (EIN) and enzyme IIA(Glucose) (IIA(Glc)), reveals a number of common features despite the fact that EIN, IIA(Glc), and IIA(Mtl) bear no structural resemblance to one another. Thus, entirely different underlying structural elements can form binding surfaces for HPr that are similar in terms of both shape and residue composition. These structural comparisons illustrate the roles of surface and residue complementarity, redundancy, incremental build-up of specificity and conformational side chain plasticity in the formation of transient specific protein-protein complexes in signal transduction pathways.
Laboratory of Chemical Physics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Gabriel
G
Cornilescu
Byeong Ryong
BR
Lee
Claudia C
CC
Cornilescu
Guangshun
G
Wang
Alan
A
Peterkofsky
G Marius
GM
Clore
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D017124:Conserved Sequence; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D009004:Monosaccharide Transport Proteins; D012996:Solutions; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C022358:mannitol PTS permease, E coli; C030182:phosphocarrier protein HPr