Dataset Information

Dispersion from C? or NH: 4D experiments for backbone resonance assignment of intrinsically disordered proteins.

ABSTRACT: Resonance assignment of intrinsically disordered proteins is remarkably challenging due to scant chemical shift dispersion arising from conformational heterogeneity. The challenge is even greater if repeating segments are present in the amino acid sequence. To forward unambiguous resonance assignment of intrinsically disordered proteins, we present iHACANCO, HACACON and (HACA)CONCAHA, three H?-detected 4D experiments with C? as an additional dimension. In addition, we present (HACA)CON(CA)NH and (HACA)N(CA)CONH, new 4D H?-start, HN-detect experiments which have two NH dimensions to enhance peak dispersion in a sequential walk through C', NH and HN, and provide more accurate NH/HN chemical shifts than those that can be obtained from a crowded 1H, 15N-HSQC spectrum. Application of these 4D experiments is demonstrated using BilRI (165 aa), an outer-membrane intrinsically disordered protein from the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans. BilRI amino acid sequence encompasses three very similar repeats with a 13-residue identical stretch in two of them.

SUBMITTER: Tossavainen H

PROVIDER: S-EPMC7080685 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Dispersion from Cα or NH: 4D experiments for backbone resonance assignment of intrinsically disordered proteins.

Tossavainen Helena H Salovaara Santeri S Hellman Maarit M Ihalin Riikka R Permi Perttu P

Journal of biomolecular NMR 20200113 2-3

Resonance assignment of intrinsically disordered proteins is remarkably challenging due to scant chemical shift dispersion arising from conformational heterogeneity. The challenge is even greater if repeating segments are present in the amino acid sequence. To forward unambiguous resonance assignment of intrinsically disordered proteins, we present iHACANCO, HACACON and (HACA)CONCAHA, three Hα-detected 4D experiments with Cα as an additional dimension. In addition, we prese ...[more]

PMID: 31932991

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Project description:Experimental residual dipolar couplings (RDCs) in combination with structural models have the potential for accelerating the protein backbone resonance assignment process because RDCs can be measured accurately and interpreted quantitatively. However, this application has been limited due to the need for very high-resolution structural templates. Here, we introduce a new approach to resonance assignment based on optimal agreement between the experimental and calculated RDCs from a structural template that contains all assignable residues. To overcome the inherent computational complexity of such a global search, we have adopted an efficient two-stage search algorithm and included connectivity data from conventional assignment experiments. In the first stage, a list of strings of resonances (CA-links) is generated via exhaustive searches for short segments of sequentially connected residues in a protein (local templates), and then ranked by the agreement of the experimental (13)C(α) chemical shifts and (15)N-(1)H RDCs to the predicted values for each local template. In the second stage, the top CA-links for different local templates in stage I are combinatorially connected to produce CA-links for all assignable residues. The resulting CA-links are ranked for resonance assignment according to their measured RDCs and predicted values from a tertiary structure. Since the final RDC ranking of CA-links includes all assignable residues and the assignment is derived from a "global minimum", our approach is far less reliant on the quality of experimental data and structural templates. The present approach is validated with the assignments of several proteins, including a 42 kDa maltose binding protein (MBP) using RDCs and structural templates of varying quality. Since backbone resonance assignment is an essential first step for most of biomolecular NMR applications and is often a bottleneck for large systems, we expect that this new approach will improve the efficiency of the assignment process for small and medium size proteins and will extend the size limits assignable by current methods for proteins with structural models.

Dataset Information

Dispersion from C? or NH: 4D experiments for backbone resonance assignment of intrinsically disordered proteins.

Publications

Dispersion from C<sup>α</sup> or N<sup>H</sup>: 4D experiments for backbone resonance assignment of intrinsically disordered proteins.

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