Up-regulation of neutrophil activating protein in Helicobacter pylori under high-salt stress: Structural and phylogenetic comparison with bacterial iron-binding ferritins
Journal
Biochimie
Journal Volume
95
Journal Issue
6
Pages
1136-1145
Date Issued
2013
Author(s)
Abstract
It is generally accepted that most gastrointestinal diseases are probably caused by the bacterial pathogen Helicobacter pylori (H. pylori). In this study we have focused on the comparison of protein expression profiles of H. pylori grown under normal and high-salt conditions by a proteomics approach. We have identified about 190 proteins whose expression levels changed after growth at high salt concentration. Among these proteins, neutrophil-activating protein (NapA) was found to be consistently up-regulated under osmotic stress brought by high salts. We have investigated the effect of high salt on secondary and tertiary structures of NapA by circular dichroism spectroscopy followed by analytical ultracentrifugation to monitor the change of quaternary structure of recombinant NapA with increasing salt concentration. The loss of iron-binding activity of NapA coupled with noticeable energetic variation in protein association of NapA as revealed by isothermal titration calorimetry was found under high salt condition. The phylogenetic tree analysis based on sequence comparison of 16 protein sequences encompassing NapA proteins and ferritin of H. pylori and other prokaryotic organisms pointed to the fact that all H. pylori NapA proteins of human origin are more homologous to NapA of Helicobacter genus than to other bacterial NapA. Based on computer modeling, NapA proteins from H. pylori of human isolates are found more similar to ferritin from H. pylori than to NapA from other species of bacteria. Taken together, these results suggested that divergent evolution of NapA and ferritin possessing dissimilar and diverse sequences follows a path distinct from that of convergent evolution of NapA and ferritin with similar dual functionality of iron-binding and ferroxidase activities. ? 2013 Elsevier Masson SAS. All rights reserved.
Subjects
Analytical ultracentrifugation; Helicobacter pylori; High-salt stress; Iron-binding protein; Isothermal titration calorimetry; Neutrophil-activating protein
SDGs
Other Subjects
bacterial protein; ceruloplasmin; ferritin; neutrophil activating protein; unclassified drug; amino acid sequence; article; bacterial growth; circular dichroism; comparative study; computer model; Helicobacter pylori; human; iron binding capacity; isothermal titration calorimetry; nonhuman; osmotic stress; phylogenetic tree; phylogeny; protein analysis; protein expression; protein quaternary structure; protein secondary structure; protein tertiary structure; proteomics; salt stress; sequence alignment; structure analysis; ultracentrifugation; upregulation; Amino Acid Sequence; Bacterial Proteins; Biological Evolution; Electrophoresis, Gel, Two-Dimensional; Ferritins; Helicobacter Infections; Helicobacter pylori; Humans; Models, Molecular; Molecular Sequence Data; Osmotic Pressure; Phylogeny; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Up-Regulation; Bacteria (microorganisms); Helicobacter; Helicobacter pylori; Prokaryota
Type
journal article