Phytochromes are a collection of bilin-containing photoreceptors that regulate numerous photoresponses in plants and microorganisms through their ability to photointerconvert between a red light-absorbing, ground state Pr and a far-red light-absorbing, photoactivated state Pfr. While the structures of several phytochromes as Pr have been determined, little is known about the structure of Pfr and how it initiates signaling. Here, we describe the three-dimensional

We describe a novel method for the robust, rapid, and reliable determination of J couplings in multidimensional NMR coupling data, including small couplings from larger proteins. The method, ‘‘High-resolution Iterative Frequency Identification of Couplings’’ (HIFI-C) is an extension of the adaptive and intelligent data collection approach introduced earlier in HIFI-NMR. HIFI-C collects one or more optimally tilted two-dimensional (2D) planes

The solution structure of the complex between the cytoplasmic A domain (IIAMtl) of the mannitol transporter IIMannitol and the histidine-containing phosphocarrier protein (HPr) of the Escherichia coli phosphotransferase system (PTS) 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

The changes in a solute’s chemical shifts between an isotropic and a liquid crystalline phase provide information on the magnitude and orientation of the chemical shielding tensors relative to the molecule’s alignment frame. Such chemical shift changes have been measured for the polypeptide backbone C', N, and HN resonances in the protein ubiquitin. Perdeuterated ubiquitin was dissolved in a medium containing a small volume fraction of phospholipid

One-bond 1JCaCb scalar couplings, measured in ubiquitin, exhibit a strong dependence on the local backbone conformation. Empirically, the deviation from the 1JCaCb value measured in the corresponding free amino acid, can be expressed as delta(1JCaCb) = 1.3 + 0.6 cos(psi-61°) + 2.2 cos[2(psi-61°)] - 0.9 cos[2(phi + 20°)] +/- 0.5 Hz, where phi and psi are the intraresidue polypeptide backbone torsion angles obtained from ubiquitin's X-ray structure.

Establishing a quantitative relationship between backbone-backbone hydrogen bond length observed in protein crystal structures and the measured 3hJNC' couplings across such bonds is limited by the coordinate precision of the X-ray structure. For an immunoglobulin binding domain of Streptococcal protein G, very high resolution X-ray structures are available. It is demonstrated that over the small range of N-O hydrogen bond lengths (2.8-3.3 A;) for

It is demonstrated that scalar couplings between a hydrogen bond donating 15N nucleus and a hydrogen bond accepting 13C’ nucleus can readily be observed in the uniformly 13C/15N-enriched protein ubiquitin. These scalar couplings, hJNC’, are observed for all regular beta-sheet hydrogen bonds, and for all but two of the alpha-helical hydrogen bonds observed in the crystal structure. The magnitude of hJNC’ is larger for b-sheet (0.56±0.10) Hz