Sarah Kuschert, Martin Stroet, Yanni Ka-Yan Chin, Anne Claire Conibear, Xinying Jia, Thomas Lee, Christian Reinhard Otto Bartling, Kristian Strømgaard, Peter Güntert, Karl Johan Rosengren, Alan Edward Mark, and Mehdi Mobli
The 20 genetically encoded amino acids provide the basis for most proteins and peptides that make up the machinery of life. This limited repertoire is vastly expanded by the introduction of non-canonical amino acids (ncAAs). Studying the structure of protein-containing ncAAs requires new computational representations that are compatible with existing modelling software. We have developed an online tool for this to aid future structural studies of this class of complex biopolymer.
Sreelakshmi Mekkattu Tharayil, Mithun C. Mahawaththa, Akiva Feintuch, Ansis Maleckis, Sven Ullrich, Richard Morewood, Michael J. Maxwell, Thomas Huber, Christoph Nitsche, Daniella Goldfarb, and Gottfried Otting
Having shown that tagging a protein at a single site with different lanthanoid complexes delivers outstanding structural information at a selected site of a protein (such as active sites and ligand binding sites), we now present a simple way by which different lanthanoid complexes can be assembled on a highly solvent-exposed cysteine residue. Furthermore, the chemical assembly is selective for selenocysteine, if a selenocysteine residue can be introduced into the protein of interest.
We show here that binding of the anticancer drug imatinib to the ATP site of Abelson kinase and not binding to its allosteric site coincides with the opening of the kinase regulatory core at nanomolar concentrations. This has implications for the understanding of Abelson’s kinase regulation and activity during medication as well as for the design of new Abelson kinase inhibitors.
Installing a tag containing a paramagnetic metal ion on a protein can lead to large changes (pseudocontact shifts) in the resonances observed in NMR spectra. These are easily measured and contain valuable long-range structural information. The present work shows that a single tagging site furnished with different tags can be sufficient to localise atoms in proteins with high accuracy. In fact, this strategy works almost as well as the same number of tags distributed over multiple tagging sites.
This paper explores a method for determining the solution structure of a solvent-exposed polypeptide segment (the L3 loop), which is next to the active site of the penicillin-degrading enzyme IMP-1. Tagging three different sites on the protein with paramagnetic metal ions allowed positioning of the L3 loop with atomic resolution. It was found that the method was more robust when omitting data obtained with different metal ions if obtained with the same tag at the same tagging site.
Fluorine NMR was used to study the interaction between a proline-rich peptide and a SH3 domain using 4S- and 4R-fluorinated prolines whose potential as NMR probes has not been exploited yet. We present a comprehensive study addressing several aspects to be considered when using these residues as NMR probes, including relaxation and dynamics. We show that their conformational bias may be used to modulate the kinetics of protein binding to proline-rich motifs.
We describe a suite of experiments that exploit field-dependent relaxation measurements of four-spin transitions in methyl groups to characterise chemical exchange processes and which can be used as an alternative or complement to CPMG relaxation dispersion measurements. We show that these four-spin transitions benefit from the methyl TROSY effect and so provide a unique combination of slow intrinsic relaxation and high sensitivity to chemical exchange.
The Biological Magnetic Resonance Data Bank (BMRB) has been used to identify overall trends, for example, the relationship between chemical shift and backbone conformation. The BMRB archive has grown so that statistical outliers are sufficiently numerous to afford insights into unusual or unique structural features in proteins. We analyze amide proton chemical shift outliers to gain insights into the occurrence of hydrogen bonds between an amide NH and the p-pi cloud of aromatic sidechains.
There is growing interest in mapping exchange dynamics between Watson–Crick and Hoogsteen conformations across different DNA contexts. However, current methods are ill-suited for measurements at a large scale because they require isotopically enriched samples. We report that Hoogsteen dynamics can be measured on unlabeled samples using 1H CEST experiments, which have higher throughput and lower cost relative to conventional methods and also provide new insights into Hoogsteen dynamics.
The overall aim of the study is to provide a basis from which to improve the ability of tamoxifen family drugs to reduce the activity of a secondary target protein, calmodulin, during tumour development. The main conclusion is that the binding of a tamoxifen analogue is quite unlike that of other anti-calmodulin compounds in that two drug molecules bring the two domains of calmodulin into close proximity, but they are not fixed in orientation relative to the protein.
Trigger factor (TF) is a conserved bacterial molecular chaperone that exists in a monomer–dimer equilibrium in solution. It binds to the ribosome as a monomer to facilitate folding of nascent polypeptide chains. We showed that dimeric TF exhibits distinct domain dynamics and conformational polymorphism and that TF contains multiple substrate binding sites that are only accessible in its monomeric form. The equilibrium of TF in different oligomeric states may serve as a regulatory mechanism.
The Wnt signalling pathway plays a major role in prevention of cancer, whereby the protein Dishevelled connects from the transmembrane receptor Frizzled to downstream effectors via its PDZ domain. Here, cycles of chemical synthesis and structural biology are applied to develop PDZ ligands that block the Frizzled–Dishevelled interaction using NMR for screening, in ligand development, and for deriving structure–activity relationships. Cellular reporter assays demonstrate their efficacy.
The folding, refolding and misfolding of biomacromolecules including proteins, DNA and RNA is an important area of biophysical research to understand functional and disease states of a cell. NMR spectroscopy provides detailed insight, with both high time and atomic resolution. These experiments put stringent requirements on signal-to-noise for often irreversible folding reactions. The review describes methodological approaches and highlights key applications.
The iron–sulfur cluster binding properties of human mitoNEET have been investigated by 1D and 2D 1H paramagnetic NMR spectroscopy. The NMR spectra of both oxidized and reduced mitoNEET are significantly different from those reported previously for other [Fe2S2] proteins. Our findings revealed the unique electronic properties of mitoNEET and suggests that the specific electronic structure of the cluster possibly drives the functional properties of different [Fe2S2] proteins.
While most proteins adopt one conformation, several interconvert between two or more very different structures. Knowing how sequence changes and small-molecule binding can control this behavior is essential for both understanding biology and inspiring new “molecular switches” which can control cellular pathways. This work contributes by examining these topics in the ARNT protein, showing that features of both the folded and unfolded states contribute to the interconversion process.
A method is demonstrated that can help in sequence-specific NMR signal assignment to nuclear spins near a strongly paramagnetic metal in an enzyme. A combination of paramagnetically tailored NMR experiments and second-shell mutagenesis was used to attribute previously observed chemical exchange processes in the active site of laccase to specific histidine ligands. The signals of nuclei close to the metal can be used as spies to unravel the role of motions in the catalytic process.
A new way is presented for creating lanthanide binding sites on proteins using site-specifically introduced phosphoserine residues. The paramagnetic effects of lanthanides generate long-range effects, which contain structural information and are readily measured by NMR spectroscopy. Excellent correlations between experimentally observed and back-calculated pseudocontact shifts attest to very good immobilization of the lanthanide ions relative to the proteins.
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Although both the hydrophobic aliphatic chain and hydrophilic ζ-amino group of the lysine side chain presumably contribute to the structures and functions of proteins, the dual nature of the lysine residue has not been fully understood yet, due to the lack of appropriate methods to acquire comprehensive information on its long consecutive methylene chain at the atomic scale. We describe herein a novel strategy to address the current situation using nuclear magnetic resonance spectroscopy.
Although both the hydrophobic aliphatic chain and hydrophilic ζ-amino group of the lysine side...