Bacterial iron acquisition mediated by outer membrane translocation and cleavage of a host protein
| Autor: | Amaya Albalat, Daniel Walker, Marta Wojnowska, Khedidja Mosbahi |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Siderophore Iron Pectobacterium 030106 microbiology Iron–sulfur cluster ATP-binding cassette transporter outer membrane Microbiology 03 medical and health sciences chemistry.chemical_compound Bacterial Proteins M16 protease Ferredoxin 2. Zero hunger protein translocation Multidisciplinary biology Chemistry Binding protein Cell Membrane food and beverages Membrane Proteins Periplasmic space Biological Sciences Peptide Elongation Factor G ferredoxin biology.organism_classification 030104 developmental biology Biochemistry Periplasm Proteolysis bacteria Bacterial outer membrane Bacteria |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1800672115 |
| Popis: | Significance The outer membrane of Gram-negative bacteria is a highly impermeable barrier to a range of toxic chemicals and is responsible for the resistance of these bacteria to important classes of antibiotics. In this work, we show that plant pathogenic Pectobacterium spp. acquire iron from the small, stable, and abundant iron-containing plant protein ferredoxin by transporting ferredoxin across the outer membrane for intracellular processing by a highly specific protease, which induces iron release. The presence of homologous uptake and processing proteins in a range of important animal and plant pathogens suggests an exploitable route through which large molecules can penetrate the outer membrane of Gram-negative bacteria. Iron is an essential micronutrient for most bacteria and is obtained from iron-chelating siderophores or directly from iron-containing host proteins. For Gram-negative bacteria, classical iron transport systems consist of an outer membrane receptor, a periplasmic binding protein, and an inner membrane ABC transporter, which work in concert to deliver iron from the cell surface to the cytoplasm. We recently showed that Pectobacterium spp. are able to acquire iron from ferredoxin, a small and stable 2Fe-2S iron sulfur cluster containing protein and identified the ferredoxin receptor, FusA, a TonB-dependent receptor that binds ferredoxin on the cell surface. The genetic context of fusA suggests an atypical iron acquisition system, lacking a periplasmic binding protein, although the mechanism through which iron is extracted from the captured ferredoxin has remained unknown. Here we show that FusC, an M16 family protease, displays a highly targeted proteolytic activity against plant ferredoxin, and that growth enhancement of Pectobacterium due to iron acquisition from ferredoxin is FusC-dependent. The periplasmic location of FusC indicates a mechanism in which ferredoxin is imported into the periplasm via FusA before cleavage by FusC, as confirmed by the uptake and accumulation of ferredoxin in the periplasm in a strain lacking fusC. The existence of homologous uptake systems in a range of pathogenic bacteria suggests that protein uptake for nutrient acquisition may be widespread in bacteria and shows that, similar to their endosymbiotic descendants mitochondria and chloroplasts, bacteria produce dedicated protein import systems. |
| Databáze: | OpenAIRE |
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