The bacteriocin armamentarium of Pseudomonas
Abstract
In order to harness itself or to gain ground in competitive niches, the metabolically versatile genus
Pseudomonas has several antagonism-mediating tools available. One well-studied group are secreted
antibacterial proteins, designated bacteriocins. In Pseudomonas aeruginosa, large phage tail-like
bacteriocins (R and F pyocins) and smaller modular bacteriocins (S pyocins) have previously been
studied. More recently, L-type pyocins have been added to these ribosomally encoded antibacterials.
We performed a comprehensive analysis on full and draft genomes of pseudomonads to explore
their armamentarium of bacteriocin genes. In addition to underpinning the highly strain-specific
nature of bacteriocinogeny, this study revealed that the structural and functional diversity of
pseudomonad bacteriocins is much broader than estimated from the currently characterized
bacteriocins. In particular for S-type bacteriocins, their modular domain architecture apparently has
driven extensive diversification. The majority of these bacteriotoxic molecules are equipped with an
enzymatic activity destroying nucleic acids of an invaded target cell, necessitating co-expression of
cognate immunity proteins to prevent suicidal toxin production. Toxin-antitoxin modules are found in
combination with various target-specifying receptor-binding domains. Furthermore, these toxinantitoxin modules also appear in antagonism-mediating complexes of a different nature such as Rhs
proteins and CDI proteins. The dynamic nature of the pseudomonad bacteriocins is further illustrated
by the occurrence of novel bacteriocin architectures in which two toxin modules are integrated, i.e.
two DNase domains or a peptidoglycan-affecting function combined with membrane pore formation
activity.
The typical architecture of S-type bacteriotoxins is absent from L-type bacteriocins. The latter consist
of a tandem of monocot mannose-binding lectin (MMBL) domains, one domain involved in LPS
binding, the other domain defining target strain specificity. Our study also revealed several
Pseudomonas proteins containing only a single MMBL domain and we showed that these proteins
also possess anti-pseudomonad activity, hence representing a novel L-type bacteriocin in which the
strain-specific killing function is essentially condensed into a single MMBL domain. Contrary to S-type
pyocins, these L-type bacteriocins are often associated with prophage gene clusters, suggesting a
hitchhiking strategy for horizontal spreading.
When and where will the conference take place?
13/03/2015-16/03/2015, Washington, USA, @ASM Conference on Mechanisms of Interbacterial
Cooperation and Competition
Which mode of transport will you be using?
Vliegtuig
Please mention all other funding that you have applied for or that you have already obtained for
this conference. (Optional) 2000 characters
At this moment no other funding has been obtained to attend this conference. I also plan to apply for
a conference grant at the Academische Stichting Leuven. Therefore, applying at FWO for a "Krediet
voor deelname aan congres in het buitenland" is a prerequisite.
What is the added scientific value of the participation? 5000 characters
The @ASM Conference on Mechanisms of Interbacterial Cooperation and Competition is a new
format of focused conferences in which the American Society for Microbiology aims to bring together
a selection of top scientists in a certain field from all over the world. Without any doubt, ASM is the
leading microbiology society in the world. This is reflected by an impressive list of invited speakers at
this conference (from the universities of Oxford, Imperial College, Harvard, etc.): several of them
have multiple top-impact papers and/or are editor in leading journals in the field, such as
Nature/Science, mBio, PLoS journals; suggesting a meeting of very high level. To this extent, meeting
these scientists would be very interesting in terms of networking and to meet potential referees.
Furthermore, this is a focused meeting, with selected attendees. Therefore, subjects presented will
be of a high level and constitute cutting edge science. The conference topic also covers well the
research I am currently performing on the mode of action of highly specific bacteriotoxins. In our
recent review published in FEMS Microbiology Reviews we have highlighted commonalities between
bacteriocins and other antibacterial proteins, and this aspect is a major theme at this conference.
Therefore, being present at this focused meeting will ensure presentation of many interesting topics
and give an overview about emerging trends in the field. Attending this conference will expand my
personal knowledge in the area, including potential alternative or novel experimental approaches,
and also create opportunities for collaboration with leading scientists working on similar projects.
Proof of acceptance
There is no proof of acceptance yet.
Please provide full bibliographic details of your three main publications in the last five years. List
all authors, title of publications and journal name (without abbreviations) with volume, page and
year. Mention impact factor of the journal and whether the publication was peer reviewed or not.
9000 characters.
 Ghequire, M., De Mot, R. (2014). Ribosomally encoded antibacterial proteins and peptides from
Pseudomonas. FEMS Microbiology Reviews, 38 (4), 523-568. IF2013: 13.806. Peer-reviewed
 Ghequire, M., Garcia-Pino, A., Lebbe, E., Spaepen, S., Loris, R., De Mot, R. (2013). Structural
determinants for activity and specificity of the bacterial toxin LlpA. PLoS Pathogens, 9 (2), art.nr.
e1003199. IF2013: 8.057. Peer-reviewed
 Ghequire, M., Dingemans, J., Pirnay, J., De Vos, D., Cornelis, P., De Mot, R. (2014). O serotypeindependent susceptibility of Pseudomonas aeruginosa to lectin-like pyocins. MicrobiologyOpen.
doi:10.1002/mbo3.210. IF: pending. Peer-reviewed
What is the title of your presentation. 240 characters.
Specify the type of your presentation.
Oral presentation
Give an abstract of your presentation. Mention the general background, the subject, the
methodology used, and the main findings and conclusions. 4000 characters.
Specify all authors. 9000 characters.
 Maarten G. K. Ghequire, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20 bus
2460, 3001 Heverlee, Belgium
 René De Mot, Centre of Microbial and Plant Genetics, Kasteelpark Arenberg 20 bus 2460,
3001 Heverlee, Belgium
URL of the program. (Optional). 500 characters.
http://conferences.asm.org/index.php/upcoming-conferences/asm-mechanisms-of-interbacterialcooperation-and-competition
Specify the scientific field in which your research is situated.
BIO
Add the supervisor, appointed at a Flemish host institution.
René De Mot, rene.demot@biw.kuleuven.be