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Updated: Apr 7, 2026
Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins
Published on: September 23, 2021
NMR assignment of intrinsically disordered self-processing module of the FrpC protein of Neisseria meningitidis
Vojtěch Kubáň1, Jiří Nováček1, Ladislav Bumba2
1CEITEC, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic.
Abstract:
The self-processing module (SPM) is an internal segment of the FrpC protein (P415-F591) secreted by the pathogenic Gram-negative bacterium Neisseria meningitidis during meningococcal infection of human upper respiratory tract. SPM mediates 'protein trans-splicing', a unique natural mechanism for editing of proteins, which involves a calcium-dependent autocatalytic cleavage of the peptide bond between D414 and P415 and covalent linkage of the cleaved fragment through its carboxy-terminal group of D414 to [Formula: see text]-amino group of lysine residue within a neighboring polypeptide chain. We present an NMR resonance assignment of the calcium-free SPM, which displays characteristic features of intrinsically disordered proteins. Non-uniformly sampled 5D HN(CA)CONH, 4D HCBCACON, and HCBCANCO spectra were recorded to resolve poorly dispersed resonance frequencies of the disordered protein and 91 % of SPM residues were unambiguously assigned. Analysis of the chemical shifts revealed that two regions of the intrinsically disordered SPM (A95-S101 and R120-I127) have a tendency to form a helical structure, whereas the residues P1-D7 and G36-A40 have the propensity to adopt a [Formula: see text]-structure.
Insights
Neisseria meningitidis secretes a self-processing module (SPM) that performs protein trans-splicing. NMR analysis reveals the calcium-free SPM is intrinsically disordered, with specific regions showing helical or beta-sheet propensities.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- The pathogenic bacterium Neisseria meningitidis secretes the FrpC protein containing a self-processing module (SPM).
- SPM mediates protein trans-splicing, a calcium-dependent autocatalytic process involving peptide bond cleavage and covalent linkage.
Purpose of the Study:
- To determine the NMR resonance assignment of the calcium-free SPM.
- To characterize the structural properties of the intrinsically disordered SPM.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
- Non-uniformly sampled 5D HN(CA)CONH, 4D HCBCACON, and HCBCANCO spectra were recorded.
- 91% of SPM residues were assigned using chemical shift analysis.
Main Results:
- The calcium-free SPM exhibits characteristics of intrinsically disordered proteins.
- Specific regions (A95-S101 and R120-I127) show a propensity for helical structure.
- Other regions (P1-D7 and G36-A40) tend to adopt a beta-sheet structure.
Conclusions:
- The study provides the first NMR resonance assignment for calcium-free SPM.
- Structural analysis reveals localized helical and beta-sheet propensities within the intrinsically disordered SPM.
- These findings contribute to understanding the mechanism of protein trans-splicing in Neisseria meningitidis.
