Molecular Insights into Conformational Heterogeneity and Enhanced Structural Integrity of Helicobacter pylori DNA Binding Protein Hup at Low pH

Biochemistry. 2021 Nov 2;60(43):3236-3252. doi: 10.1021/acs.biochem.1c00395. Epub 2021 Oct 19.

Abstract

The summarized amalgam of internal relaxation modulations and external forces like pH, temperature, and solvent conditions determine the protein structure, stability, and function. In a free-energy landscape, although conformers are arranged in vertical hierarchy, there exist several adjacent parallel sets with conformers occupying equivalent energy cleft. Such conformational states are pre-requisites for the functioning of proteins that have oscillating environmental conditions. As these conformational changes have utterly small re-arrangements, nuclear magnetic resonance (NMR) spectroscopy is unique in elucidating the structure-dynamics-stability-function relationships for such conformations. Helicobacter pylori survives and causes gastric cancer at extremely low pH also. However, least is known as to how the genome of the pathogen is protected from reactive oxygen species (ROS) scavenging in the gut at low pH under acidic stress. In the current study, biophysical characteristics of H. pylori DNA binding protein (Hup) have been elucidated at pH 2 using a combination of circular dichroism, fluorescence, NMR spectroscopy, and molecular dynamics simulations. Interestingly, the protein was found to have conserved structural features, differential backbone dynamics, enhanced stability, and DNA binding ability at low pH as well. In summary, the study suggests the partaking of Hup protein even at low pH in DNA protection for maintaining the genome integrity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacterial Proteins / physiology
  • Carrier Proteins / metabolism
  • Circular Dichroism / methods
  • DNA / chemistry
  • DNA / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • DNA-Binding Proteins / physiology
  • Entropy
  • Fluorescence
  • Helicobacter pylori / metabolism*
  • Helicobacter pylori / pathogenicity
  • Hydrogen-Ion Concentration
  • Magnetic Resonance Spectroscopy / methods
  • Molecular Conformation
  • Molecular Dynamics Simulation
  • Reactive Oxygen Species / metabolism
  • Solvents / chemistry
  • Temperature

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • DNA-Binding Proteins
  • Reactive Oxygen Species
  • Solvents
  • histone-like protein HU, bacteria
  • DNA