#FEMSmicroBlog: Enterococci using heme during infections

22-10-2024

As an iron carrier, heme is a highly important molecule for both humans and bacteria. Many bacteria developed sophisticated ways to use heme as a cofactor to increase their fitness and thrive in challenging environments. The review “Heme utilization by the enterococci” in FEMS Microbes outlines the various roles heme plays in these opportunistic pathogens as well as in host-pathogen and interspecies bacterial interactions, as explained by Debra Brunson. #FascinatingMicrobes

 

Can you summarize the significance of your paper for microbiologists outside of your field?

Heme is an important biomolecule that influences interactions between different bacteria as well as between bacteria and their hosts. For example, heme is an essential cofactor for catalase, an enzyme to detox hydrogen peroxide. Both humans and some bacteria use hydrogen peroxide to combat pathogens and antagonize competitors.

Opportunistic pathogens, such as the enterococci, contain sophisticated mechanisms to sense and utilize heme during infection. Hence, better understanding these mechanisms is highly relevant to identifying novel approaches to combat infections.

Our review highlights proteins that transport, sense, or use heme as a cofactor in the opportunistic human pathogen Enterococcus faecalis. We also describe and discuss the uneven distribution of heme-associated proteins in the enterococci in terms of their evolutionary history.

 

Why is your study important for society or non-scientists?

Enterococci are important members of the human gut microbiome. Depending on environmental triggers, they can have positive or negative impacts on gut health.

In addition, at least two species of the genus, Enterococcus faecalis and Enterococcus faecium, are major opportunistic pathogens. This means they are able to cause life-threatening and multidrug-resistant infections.

In this review, we discuss how heme metabolism influences Enterococcus faecalis interspecies and host-pathogen interactions. We explain the possibility that during infection, Enterococcus faecalis might be capable of exploiting heme produced by the host for its own benefit.

Mechanisms of heme acquisition, utilization, and export in enterococci.
Mechanisms of heme acquisition, utilization, and export in enterococci. From Brunson and Lemon (2024).

 

Why did you choose to dive into this field? What fascinates you about the topic?

My research as a graduate student brought me into the field of biometals. Initially, I focused on identifying and characterizing iron uptake mechanisms in Enterococcus faecalis. Over time, my studies evolved to also investigate how Enterococcus faecalis can utilize heme as an iron source and enzymatic co-factor.

I am fascinated by biometals and their functions in host-pathogen interactions. When writing this review, my goal was to highlight the importance of heme for bacteria, as well as for their interactions with the host and other bacteria.

 

What keeps you going in the face of adversities?

The love of science! Whenever I run into an unsuccessful or inconclusive experiment, I reenergize myself by diving into the literature to learn other ways I can overcome these hurdles. I always find something and that is the great thing about science; there is always a way forward!

 

You decided to opt for the Transparent Peer Review route offered by FEMS Microbes. What motivated you to do so, and what are the benefits in your opinion?

For me, peer review transparency increases fairness and helps the reader understand the review process. As an early-career scientist, I also think that review transparency is useful to those with less experience in writing and/or reviewing manuscripts.

 

About the author

Debra Brunson received her bachelor’s degree in microbiology from Idaho State University where she developed her interest in host-pathogen interactions. She also received a master’s in biology from the University of North Florida, where she studied the impacts of outer membrane porin loss on the physiology of Klebsiella pneumoniae. In 2023, Debra graduated from the Biomedical Sciences Ph.D. program at UF. Her project focused on the characterization of iron transporters and interpreting the importance of iron homeostasis to the virulence of Enterococcus faecalis. After graduation, Debra chose to remain in the Lemos-Abranches lab to further her research into mechanisms of heme utilization by E. faecalis as a postdoctoral associate.

About this blog section

The section #FascinatingMicrobes for the #FEMSmicroBlog explains the science behind a paper and highlights the significance and broader context of a recent finding. One of the main goals is to share the fascinating spectrum of microbes across all fields of microbiology.

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