Flavin Reductase Contributes to Pneumococcal Virulence by Protecting from Oxidative Stress and Mediating Adhesion and Elicits Protection Against Pneumococcal Challenge

Research output: Contribution to journalArticle

Authors

  • Giora I Morozov
  • Nurith Porat
  • Tatyana Kushnir
  • Hastyar Najmuldeen
  • Asad Adawi
  • Vered Chalifa-Caspi
  • Rachel Benisty
  • Ariel Ohayon
  • Ofir Liron
  • Shalhevet Azriel
  • Itai Malka
  • Shahar Dotan
  • Maxim Portnoi
  • Andrew A Piotrowski
  • Daniel Kafka
  • Barak Hajaj
  • Tali Fishilevich
  • Marilou Shagan
  • Michael Tal
  • Ron Ellis
  • Donald A Morrison
  • Ron Dagan
  • Hasan Yesilkaya
  • Yaffa Mizrachi Nebenzahl

External organisations

  • The Shraga Segal Department of Microbiology and Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
  • Pediatric Infectious Disease Unit, Soroka University Medical Center, Beer Sheva, Israel.
  • Department of Biology, College of Science, University of Sulaimani, Sulaymaniyah, Iraq.
  • National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
  • NasVax, Ness Ziona, Israel.
  • Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA.
  • Institute of Microbiology and Infection, College of Medical and Dental Sciences, The University of Birmingham, Birmingham, United Kingdom.
  • Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
  • University of Leicester
  • The Shraga Segal Department of Microbiology and Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. ymizr@bgu.ac.il.

Abstract

Pneumococcal flavin reductase (FlaR) is known to be cell-wall associated and possess age dependent antigenicity in children. This study aimed at characterizing FlaR and elucidating its involvement in pneumococcal physiology and virulence. Bioinformatic analysis of FlaR sequence identified three-conserved cysteine residues, suggesting a transition metal-binding capacity. Recombinant FlaR (rFlaR) bound Fe2+ and exhibited FAD-dependent NADP-reductase activity, which increased in the presence of cysteine or excess Fe2+ and inhibited by divalent-chelating agents. flaR mutant was highly susceptible to H2O2 compared to its wild type (WT) and complemented strains, suggesting a role for FlaR in pneumococcal oxidative stress resistance. Additionally, flaR mutant demonstrated significantly decreased mice mortality following intraperitoneal infection. Interestingly, lack of FlaR did not affect the extent of phagocytosis by primary mouse peritoneal macrophages but reduced adhesion to A549 cells compared to the WT and complemented strains. Noteworthy are the findings that immunization with rFlaR elicited protection in mice against intraperitoneal lethal challenge and anti-FlaR antisera neutralized bacterial virulence. Taken together, FlaR's roles in pneumococcal physiology and virulence, combined with its lack of significant homology to human proteins, point towards rFlaR as a vaccine candidate.

Details

Original languageEnglish
Article number314
JournalScientific Reports
Volume8
Publication statusPublished - 10 Jan 2018

Keywords

  • Journal Article