Publications by Melanie Blokesch

Capsular polysaccharide restrains type VI secretion in Acinetobacter baumannii

Mary-Claude Croisier-Coeytaux, Melanie Blokesch, Nicolas Olmo Flaugnatti, Loriane Bader

The type VI secretion system (T6SS) is a sophisticated, contact-dependent nanomachine involved in interbacterial competition. To function effectively, the T6SS must penetrate the membranes of both attacker and target bacteria. Structures associated with th ...

2025

West African–South American pandemic Vibrio cholerae encodes multiple distinct phage defence systems

Melanie Blokesch, Sandrine Stutzmann, David William Adams, Milena Jadwiga Jaskolska, Laurie Righi, Loriane Bader, Alexandre Lemopoulos

Our understanding of the factors underlying the evolutionary success of different lineages of pandemic Vibrio cholerae remains incomplete. The West African–South American (WASA) lineage of V. cholerae, responsible for the 1991–2001 Latin American cholera e ...

Springer Science and Business Media LLC2025

Exploring Mobile Genetic Elements in Vibrio cholerae

Melanie Blokesch, Natalia Carolina Drebes Dorr, Alexandre Lemopoulos

Members of the bacterial species Vibrio cholerae are known both as prominent constituents of marine environments and as the causative agents of cholera, a severe diarrheal disease. While strains responsible for cholera have been extensively studied over th ...

Oxford University Press (OUP)2025

Molecular mechanism of plasmid elimination by the DdmDE defense system

Melanie Blokesch, Sandrine Stutzmann, David William Adams, Laurie Righi

Seventh pandemic Vibrio cholerae strains contain two pathogenicity islands that encode the DNA defense modules DdmABC and DdmDE. Here we use cryogenic electron microscopy to reveal the mechanistic basis for plasmid defense by DdmDE. A structure of the DdmD ...

American Association for the Advancement of Science2024

Genome sequences of Vibrio cholerae strains isolated in the DRC between 2009 and 2012

Melanie Blokesch, Sandrine Stutzmann, Natalia Carolina Drebes Dorr, Alexandre Lemopoulos

Vibrio cholerae has caused seven cholera pandemics in the past two centuries. The seventh and ongoing pandemic has been particularly severe on the African continent. Here, we report long read-based genome sequences of six V. cholerae strains isolated in th ...

2024

Vibrio cholerae pathogenicity island 2 encodes two distinct types of restriction systems

Melanie Blokesch, David William Adams, Grazia Vizzarro, Alexandre Lemopoulos

In response to predation by bacteriophages and invasion by other mobile genetic elements such as plasmids, bacteria have evolved specialized defense systems that are often clustered together on genomic islands. The O1 El Tor strains of Vibrio cholerae resp ...

American Society for Microbiology2024

Interactions between pili affect the outcome of bacterial competition driven by the type VI secretion system

Melanie Blokesch, Anne-Florence Raphaëlle Bitbol, Simon Bernhard Otto, Richard Marie Servajean, Alexandre Lemopoulos

The bacterial type VI secretion system (T6SS) is a widespread, kin-discriminatory weapon capable of shaping microbial communities. Due to the system’s dependency on contact, cellular interactions can lead to either competition or kin protection. Cell-to-ce ...

2024

Sporadic type VI secretion in seventh pandemic Vibrio cholerae

Melanie Blokesch, Sandrine Stutzmann, Lisa Christina Metzger, Natalia Carolina Drebes Dorr, Sandrine Natacha Isaac, Nicolas René Chiaruttini, Alexis Joseph Proutière, Loriane Bader

Vibrio cholerae is a pathogen that causes disease in millions of people every year by colonizing the small intestine and then secreting the potent cholera toxin. How the pathogen overcomes the colonization barrier created by the host’s natural microbiota i ...

2023

DNA modifications impact natural transformation of Acinetobacter baumannii

Christian Iseli, Nicolas Jean Philippe Guex, Melanie Blokesch, Nina Vesel, Alexandre Lemopoulos

Acinetobacter baumannii is a dangerous nosocomial pathogen, especially due to its ability to rapidly acquire new genetic traits, including antibiotic resistance genes (ARG). In A. baumannii, natural competence for transformation, one of the primary modes o ...

2023

Recombinant bacteria resistant to horizontal gene transfer and phage infection

Melanie Blokesch, David William Adams, Milena Jadwiga Jaskolska

The invention relates to an expression vector encoding a DNA defence system comprising polypeptides derived from Vibrio cholerae, or equivalent functional variants or homologues, conferring resistance to the maintenance of extra-genomic DNA to a recipient ...

2023

Single nucleotide polymorphism determines constitutive versus inducible type VI secretion in Vibrio cholerae

Melanie Blokesch, Sandrine Stutzmann, Milena Jadwiga Jaskolska, Natalia Carolina Drebes Dorr, Alexis Joseph Proutière, Loriane Bader

Vibrio cholerae is a well-studied human pathogen that is also a common inhabitant of marine habitats. In both environments, the bacterium is subject to interbacterial competition. A molecular nanomachine that is often involved in such competitive behavior ...

2022

Two defence systems eliminate plasmids from seventh pandemic Vibrio cholerae

Melanie Blokesch, David William Adams, Milena Jadwiga Jaskolska

Horizontal gene transfer can trigger rapid shifts in bacterial evolution. Driven by a variety of mobile genetic elements—in particular bacteriophages and plasmids—the ability to share genes within and across species underpins the exceptional adaptability o ...

2022

The VarA-CsrA regulatory pathway influences cell shape in Vibrio cholerae

Melanie Blokesch, Leonardo Filipe Lemos Rocha

Despite extensive studies on the curve-shaped bacterium Vibrio cholerae, the causative agent of the diarrheal disease cholera, its virulence-associated regulatory two-component signal transduction system VarS/VarA is not well understood. This pathway, whic ...

2022

Pilus production in Acinetobacter baumannii is growth phase dependent and essential for natural transformation

Melanie Blokesch, Nina Vesel

Acinetobacter baumannii is a severe threat to human health as a frequently multidrug-resistant hospital-acquired pathogen. Part of the danger from this bacterium comes from its genome plasticity and ability to evolve quickly by taking up and recombining ex ...

American Society for Microbiology2021

Growing away from monocultures – interdependent growth conditions for studying antibacterial and antiphage systems

Melanie Blokesch

2021

Human commensal gut Proteobacteria withstand type VI secretion attacks through immunity protein-independent mechanisms

Melanie Blokesch, Candice Stoudmann, Sandrine Stutzmann, Nina Vesel, Sandrine Natacha Isaac, Leonardo Filipe Lemos Rocha, Nicolas Olmo Flaugnatti, Thibault Géry L Sana

While the major virulence factors for Vibrio cholerae, the cause of the devastating diarrheal disease cholera, have been extensively studied, the initial intestinal colonization of the bacterium is not well understood because non-human adult animals are re ...

Nature Research2021

Interbacterial competition and anti‐predatory behavior of environmental Vibrio cholerae strains

Melanie Blokesch, Natalia Carolina Drebes Dorr

Vibrio cholerae isolates responsible for cholera pandemics represent only a small portion of the diverse strains belonging to this species. Indeed, most V. cholerae are encountered in aquatic environments. To better understand the emergence of pandemic lin ...

2020

Comparison of chitin‐induced natural transformation in pandemic Vibrio cholerae O1 El Tor strains

Melanie Blokesch, Sandrine Stutzmann

The human pathogen Vibrio cholerae serves as a model organism for many important processes ranging from pathogenesis to natural transformation, which has been extensively studied in this bacterium. Previous work has deciphered important regulatory circuits ...

2020

Selection of Vibrio crassostreae relies on a plasmid expressing a type 6 secretion system cytotoxic for host immune cells

Melanie Blokesch, Candice Stoudmann, Frédérique Marie Jeanne Le Roux

Pacific oyster mortality syndrome affects juveniles of Crassostrea gigas oysters and threatens the sustainability of commercial and natural stocks of this species. Vibrio crassostreae has been repeatedly isolated from diseased animals and the majority of t ...

2020

A Vibriophage Takes Antirepression to the Next Level

Melanie Blokesch, Leonardo Filipe Lemos Rocha

Since its isolation by Esther Lederberg, phage lambda and its repressor protein CI have contributed substantially to the advancement of molecular biology. In this issue of Cell Host & Microbe, Silpe et al. (2020) characterize the antirepressor Qtip of Vibr ...

Elsevier2020