Influence of the ferric uptake regulator (Fur) protein on pathogenicity in Pectobacterium carotovorum subsp. brasiliense

PLoS One. 2017 May 17;12(5):e0177647. doi: 10.1371/journal.pone.0177647. eCollection 2017.

Abstract

Iron is an important nutrient for the survival and growth of many organisms. In order to survive, iron uptake from the environment must be strictly regulated and maintained to avoid iron toxicity. The ferric uptake regulator protein (Fur) regulates genes involved in iron homeostasis in many bacteria, including phytopathogens. However, to date, the role played by Fur in the biology of Pectobacterium carotovorum subsp. brasiliense (Pcb1692), an important pathogen of potatoes, has not yet been studied. To this end, we used the lambda recombineering method to generate a fur mutant strain of Pcb1692 and assessed the virulence and fitness of the mutant strain. The results showed that production of siderophores in Pcb1692Δfur increased compared to the Pcb1692 wild-type and the complemented strain Pcb1692Δfur-pfur. However, production of N-acyl homoserine lactone (AHLs), biofilm formation, exopolysaccharide (EPS) production, virulence on potato tubers and swimming motility, were all significantly decreased in Pcb1692Δfur compared to the wild-type and complemented Pcb1692Δfur-pfur strains. The Pcb1692Δfur mutant also demonstrated significant sensitivity to oxidative stress when exposed to H2O2. Consistent with phenotypic results, qRT-PCR results demonstrated that Fur down-regulates genes which encode proteins associated with: iron uptake (HasA-extracellular heme-binding protein and Ferrodoxin-AED-0004132), stress response (SodC-superoxide dismutase), plant cell wall degrading enzymes (PrtA and CelV) and motility (FlhC and MotA). We conclude that the ferric uptake regulator protein (Fur) of Pcb1692 regulates traits that are important to host-pathogens interactions.

MeSH terms

  • 4-Butyrolactone / analogs & derivatives
  • 4-Butyrolactone / metabolism
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biofilms / growth & development
  • Down-Regulation
  • Host-Pathogen Interactions
  • Hydrogen Peroxide / toxicity
  • Iron / metabolism
  • Mutagenesis
  • Oxidative Stress / drug effects
  • Pectobacterium carotovorum / genetics*
  • Pectobacterium carotovorum / metabolism
  • Pectobacterium carotovorum / pathogenicity*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Siderophores / metabolism
  • Solanum tuberosum / microbiology
  • Superoxide Dismutase / metabolism
  • Virulence / genetics

Substances

  • Bacterial Proteins
  • Repressor Proteins
  • Siderophores
  • ferric uptake regulating proteins, bacterial
  • homoserine lactone
  • Hydrogen Peroxide
  • Iron
  • Superoxide Dismutase
  • 4-Butyrolactone

Grants and funding

This research study was funded by the National Research Foundation (NRF), South Africa through Competitive Funding for Rated Researchers (CFRR) 98993; NRF Bioinformatics and Functional Genomics (BFG 93685) and NRF Research Technology and Transfer Fund (RTF) 98654. CKT was funded by University of Pretoria Bursary and SLP funded by the NRF Grant Holder Linked Bursary. SLP was also funded by Potatoes South Africa Transformation Bursary. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.