The Intergenomics Group is composed of
around 20 researchers with a common general research focus on
plasmid biology and, more specifically, the mechanism of bacterial
conjugation. Among the members of the group there are experts
in microbiology, bacterial genetics, protein engineering, protein
purification, crystallography, electron microscopy and biocatalysis.
This makes the Intergenomics group a powerful team that can
work independently or in cooperation with other research groups.
conjugation is the transfer of genetic material between
bacteria through direct cell-to-cell contact. Discovered in
1946 by Lederberg and Tatum, conjugation is a mechanism of horizontal
gene transfer, as are transformation and transduction, although
these mechanisms do not involve cell-to-cell contact.
conjugation is a promiscuous DNA transport mechanism. Conjugative
plasmids transfer themselves between most bacteria, thus being
one of the main causal agents of the spread of antibiotic resistance
among pathogenic bacteria.
replication and macromolecule transport across membranes are
basic processes of life. If linked, they could form the basis
for a new mechanism, DNA secretion, by simply driving the displaced
replicating DNA strand to the macromolecular transporter in
the membrane. In addition, a new protein is needed to bring
the displaced DNA in contact with the transporter: a coupling
protein. With this one and only new protein, bacteria could
have acquired the basics for conjugation, a mechanism that provides
them with a unique means for genetic exchange and a powerful
source of genetic variability.
DNA-processing enzymes and their substrate DNA sequence (components
of the so-called relaxosome) show extended sequence similarity
to rolling-circle replication (RCR) systems. Moreover, the set
of conjugative proteins that assembles the membrane transporter
belong to the type IV secretion system (T4SS) family. A protein
acts as a linker between the RCR and the T4SS. It is thus called
“coupling protein”, or T4CP, and connects the relaxosome
with the membrane transporter.
use the 34 kb conjugative plasmid R388 as a model, and have
analyzed it for nearly two decades. Our interests are, besides
the molecular mechanism of conjugation, the study of the regulatory
network of R388, the molecular structure of the individual components
and their possible uses as biocatalysts of diverse reactions.