An ECF-type transporter scavenges heme to overcome iron-limitation in Staphylococcus lugdunensis
- University of Tübingen, Germany
- University of Groningen, Netherlands
- University of Western Ontarion, Canada
- KU Leuven, Belgium
- University of Western Ontario, Canada
Abstract
Energy-coupling factor type (ECF-transporters) represent trace nutrient acquisition systems. Substrate binding components of ECF-transporters are membrane proteins with extraordinary affinity, allowing them to scavenge trace amounts of ligand. A number of molecules have been described as substrates of ECF-transporters, but an involvement in iron-acquisition is unknown. Host-induced iron limitation during infection represents an effective mechanism to limit bacterial proliferation. We identified the iron-regulated ECF-transporter Lha in the opportunistic bacterial pathogen Staphylococcus lugdunensis and show that the transporter is specific for heme. The recombinant substrate-specific subunit LhaS accepted heme from diverse host-derived hemoproteins. Using isogenic mutants and recombinant expression of Lha, we demonstrate that its function is independent of the canonical heme acquisition system Isd and allows proliferation on human cells as sources of nutrient iron. Our findings reveal a unique strategy of nutritional heme acquisition and provide the first example of an ECF-transporter involved in overcoming host-induced nutritional limitation.
Data availability
The datasets gained during the current study are available at Dryad Digital Repository under the doi:10.5061/dryad.fqz612jqc
-
Data from: An ECF-type transporter scavenges heme to overcome iron-limitation in Staphylococcus lugdunensisDryad Digital Repository, doi:10.5061/dryad.fqz612jqc.
Article and author information
Author details
Funding
Deutsche Forschungsgemeinschaft (HE8381/3-1)
- Simon Heilbronner
Deutsche Forschungsgemeinschaft (EXC2124)
- Simon Heilbronner
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (TOP grant 714.018.003)
- Dirk J Slotboom
Canadian Institutes of Health Research (PJT-153308)
- David E Heinrichs
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal experiments were performed in strict accordance with the European Health Law of the Federation of Laboratory Animal Science Associations. The protocol was approved by the Regierungspräsidium Tübingen (IMIT1/17)
Human subjects: Human Erythrocytes were isolated from venous blood of healthy volunteers in accordance with protocols approved by the Institutional Review Board for Human Subjects at the University of Tübingen. Informed written consent was obtained from all volunteers.
Copyright
© 2020, Jochim et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 2,005
- views
-
- 241
- downloads
-
- 20
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
An ECF-type transporter scavenges heme to overcome iron-limitation in Staphylococcus lugdunensis
eLife 9:e57322.
https://doi.org/10.7554/eLife.57322
Further reading
-
- Genetics and Genomics
- Microbiology and Infectious Disease
Polyamines are biologically ubiquitous cations that bind to nucleic acids, ribosomes, and phospholipids and, thereby, modulate numerous processes, including surface motility in Escherichia coli. We characterized the metabolic pathways that contribute to polyamine-dependent control of surface motility in the commonly used strain W3110 and the transcriptome of a mutant lacking a putrescine synthetic pathway that was required for surface motility. Genetic analysis showed that surface motility required type 1 pili, the simultaneous presence of two independent putrescine anabolic pathways, and modulation by putrescine transport and catabolism. An immunological assay for FimA—the major pili subunit, reverse transcription quantitative PCR of fimA, and transmission electron microscopy confirmed that pili synthesis required putrescine. Comparative RNAseq analysis of a wild type and ΔspeB mutant which exhibits impaired pili synthesis showed that the latter had fewer transcripts for pili structural genes and for fimB which codes for the phase variation recombinase that orients the fim operon promoter in the ON phase, although loss of speB did not affect the promoter orientation. Results from the RNAseq analysis also suggested (a) changes in transcripts for several transcription factor genes that affect fim operon expression, (b) compensatory mechanisms for low putrescine which implies a putrescine homeostatic network, and (c) decreased transcripts of genes for oxidative energy metabolism and iron transport which a previous genetic analysis suggests may be sufficient to account for the pili defect in putrescine synthesis mutants. We conclude that pili synthesis requires putrescine and putrescine concentration is controlled by a complex homeostatic network that includes the genes of oxidative energy metabolism.
-
- Biochemistry and Chemical Biology
- Microbiology and Infectious Disease
Glutamine synthetases (GS) are central enzymes essential for the nitrogen metabolism across all domains of life. Consequently, they have been extensively studied for more than half a century. Based on the ATP-dependent ammonium assimilation generating glutamine, GS expression and activity are strictly regulated in all organisms. In the methanogenic archaeon Methanosarcina mazei, it has been shown that the metabolite 2-oxoglutarate (2-OG) directly induces the GS activity. Besides, modulation of the activity by interaction with small proteins (GlnK1 and sP26) has been reported. Here, we show that the strong activation of M. mazei GS (GlnA1) by 2-OG is based on the 2-OG dependent dodecamer assembly of GlnA1 by using mass photometry (MP) and single particle cryo-electron microscopy (cryo-EM) analysis of purified strep-tagged GlnA1. The dodecamer assembly from dimers occurred without any detectable intermediate oligomeric state and was not affected in the presence of GlnK1. The 2.39 Å cryo-EM structure of the dodecameric complex in the presence of 12.5 mM 2-OG demonstrated that 2-OG is binding between two monomers. Thereby, 2-OG appears to induce the dodecameric assembly in a cooperative way. Furthermore, the active site is primed by an allosteric interaction cascade caused by 2-OG-binding towards an adaption of an open active state conformation. In the presence of additional glutamine, strong feedback inhibition of GS activity was observed. Since glutamine dependent disassembly of the dodecamer was excluded by MP, feedback inhibition most likely relies on the binding of glutamine to the catalytic site. Based on our findings, we propose that under nitrogen limitation the induction of M. mazei GS into a catalytically active dodecamer is not affected by GlnK1 and crucially depends on the presence of 2-OG.
