Homeostatic control of an iron repressor in a GI tract resident
- Institut Pasteur of Shanghai, China
- Shanghai Jiao Tong University, China
- Army Medical University, China
Abstract
The transition metal iron plays a crucial role in living cells. However, high levels of iron are potentially toxic through the production of reactive oxygen species (ROS), serving as a deterrent to the commensal fungus Candida albicans for colonization in the iron-rich gastrointestinal (GI) tract. We observe that the mutant lacking an iron-responsive transcription factor Hap43 is hyper-fit for colonization in murine gut. We demonstrate that high iron specifically triggers multiple post-translational modifications (PTMs) and proteasomal degradation of Hap43, a vital process guaranteeing the precision of intestinal ROS detoxification. Reduced levels of Hap43 de-repress the expression of antioxidant genes and therefore alleviate the deleterious ROS derived from iron metabolism. Our data reveal that Hap43 functions as a negative regulator for oxidative stress-adaptation of C. albicans to gut colonization and thereby provide a new insight into understanding the interplay between iron homeostasis and fungal commensalism.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting file; Source Data files have been provided for all Figures.
Article and author information
Author details
Funding
The MOST Key R&D Program of China (2022YFC2303200)
- Changbin Chen
The National Natural Science Foundation (31600119)
- Xinhuang Huang
The Natural Science Foundation of Shanghai (20ZR1463800)
- Xinhuang Huang
The Natural Science Foundation of Shanghai (15ZR1444400)
- Xinhuang Huang
The MOST Key R&D Program of China (2022YFC2304700)
- Lin Zhong
The National Natural Science Foundation (32170195)
- Changbin Chen
The Shanghai Municipal Science and Technology Major Project (2019SHZDZX02)
- Changbin Chen
The Open Project of the State Key Laboratory of Trauma, Burns and Combined Injury, Third Military Medical University (SKLKF201803)
- Changbin Chen
The Special Program of PLA (19SWAQ18)
- Huaping Liang
National Postdoctoral Fellowship (No.312780)
- Yuanyuan Wang
Shanghai Post-doctoral Excellence Program (No.2022647)
- Yuanyuan Wang
The National Natural Science Foundation (32070146)
- Xinhuang Huang
The funders had role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All animal experiments were carried out in strict accordance with the regulations in the Guide for the Care and Use of Laboratory Animals issued by the Ministry of Science and Technology of the People's Republic of China. All efforts were made to minimize suffering. The protocol was approved by IACUC at the Institut Pasteur of Shanghai, Chinese Academy of Sciences (Permit Number: A160291).
Copyright
© 2023, Wang 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
-
- 513
- views
-
- 86
- downloads
-
- 3
- 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)
Homeostatic control of an iron repressor in a GI tract resident
eLife 12:e86075.
https://doi.org/10.7554/eLife.86075
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.
