4.8 Article

Detection of weak non-covalent cation-π interactions in NGAL by single-molecule force spectroscopy

Journal

NANO RESEARCH
Volume 15, Issue 5, Pages 4251-4257

Publisher

TSINGHUA UNIV PRESS
DOI: 10.1007/s12274-021-4065-9

Keywords

cation-pi interaction; neutrophil gelatinase-associated lipocalin (NGAL); single-molecule force spectroscopy; atomic force microscopy (AFM)

Funding

  1. Fundamental Research Funds for the Central Universities [14380259]
  2. Natural Science Foundation of Jiangsu Province [BK20200058]
  3. National Natural Science Foundation of China [21771103, 21977047]

Ask authors/readers for more resources

Cation-pi interaction plays a crucial role in biological systems but its experimental verification and quantification at the molecular level are limited. In this study, atomic force microscopy-based single-molecule force spectroscopy was used to measure the stability and kinetics of NGAL protein with cation-pi interactions. The results demonstrated the high-precision detection of weak cation-pi interaction in NGAL.
Cation-pi interaction is an electrostatic interaction between a cation and an electron-rich arene. It plays an essential role in many biological systems as a vital driving force for protein folding, stability, and receptor-ligand interaction/recognition. To date, the discovery of most cation-pi interactions in proteins relies on the statistical analyses of available three-dimensional (3D) protein structures and corresponding computational calculations. However, their experimental verification and quantification remain sparse at the molecular level, mainly due to the limited methods to dynamically measure such a weak non-covalent interaction in proteins. Here, we use atomic force microscopy-based single-molecule force spectroscopy (AFM-SMFS) to measure the stability of protein neutrophil gelatinase-associated lipocalin (also known as NGAL, siderocalin, lipocalin 2) that can bind iron through the cation-pi interactions between its three cationic residues and the iron-binding tri-catechols. Based on a site-specific cysteine engineering and anchoring method, we first characterized the stability and unfolding pathways of apo-NGAL. Then, the same NGAL but bound with the iron-catechol complexes through the cation-pi interactions as a holo-form was characterized. AFM measurements demonstrated stronger stabilities and kinetics of the holo-NGAL from two pulling sites, F122 and F133. Here, NGAL is stretched from the designed cysteine close to the cationic residues for a maximum unfolding effect. Thus, our work demonstrates high-precision detection of the weak cation-pi interaction in NGAL.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.8
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available