Microbiology Editor's Choice: additional virulence factors of corynebacteria

Posted on August 1, 2019   by Microbiology Society

Each month, a manuscript published in our flagship journal Microbiology is chosen by a member of the Editorial Board. This month, the paper is titled 'Beyond diphtheria toxin: cytotoxic proteins of Corynebacterium ulcerans and Corynebacterium diphtheriae' and was chosen by Dr Jörg Stülke.

Corynebacterium diphtheriae, the causative agent of diphtheria, is regarded as one of the most important bacterial pathogens. The bacteria produce diphtheria toxin that catalyses the modification of translation factor EF-2 resulting in its inactivation. However, even strains that do not encode the diphtheria toxin can cause severe infection, indicating the existence of additional virulence factors. In the current study, Weerasekera et al. characterised a putative ribosome-binding protein that is present in strains of C. diphtheriae and C. ulcerans that cause severe disease even in the absence of diphtheria toxin. Using a broad array of functional tests, the authors could demonstrate that this protein is responsible for host damage. This study supports the idea that bacterial pathogenicity is often driven by multiple independently acting virulence factors.

Beyond diphtheria toxin: cytotoxic proteins of Corynebacterium ulcerans and Corynebacterium diphtheriae

Diphtheria toxin is the most prominent virulence factor of corynebacteria. Genome sequencing studies revealed the presence of another putative toxin in this group of Gram-positive bacteria, which has striking structural similarity to Shiga-like toxins from Gram-negatives. In this study, wild-type, mutant and overexpression strains were characterised. Depending on the presence of the toxin, detrimental effects were observed in vivo in two invertebrate model systems and in vitro in animal and human cell lines. Taken together, our results support the idea that pathogenicity of corynebacteria is a multifactorial process and that new virulence factors may influence the outcome of infections.

We spoke with corresponding author, Andreas Burkovski, about his research:

What is your institution and how long have you been there?

We have been located at Friedrich-Alexander-University of Erlangen-Nuremberg since 2005.

What is your research area?

We are working on various aspects of molecular microbiology, including biotechnology, metabolic and regulatory networks, host-pathogen interaction and synthetic biology.

What inspired you to research this topic?

The fascination about microbial diversity and adaptation to various ecological niches including animal and human hosts.

What is the most rewarding part of your research?

The interaction with students and colleagues and the fun of solving a scientific question knowing that from this the next question will arise.

What would you be doing if you weren't a scientist?

A chef, teacher or gardener.

To access the full paper, click here. Editor's Choice articles published in Microbiology are free to read.