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FWF Project

Bacterial conjugation: studies on the conjugative plasmid transfer mechanisms in Gram-positive bacteria (simplified type IV secretion mechanism), (FWF, collaboration project with Prof. Dr. W. Keller, Universität Graz)


Conjugative plasmid transfer in Gram-negative bacteria has been studied in great detail in the last decades, whereas the mechanisms of conjugative plasmid spread in Gram-positive bacteria have remained obscure. In the last few years the complete nucleotide sequences of several conjugative antibiotic resistance plasmids from Gram-positive bacteria have been determined, which revealed a modular organization of their transfer regions and high conservation of the putative transfer genes. Several genes for potential homologues of type IV secretion components involved in secretion of toxins in Gram-negative pathogens and in conjugative transfer of Gram-negative bacteria have been detected in their transfer regions. The transfer region of the multiple antibiotic resistance plasmid pIP501, with the broadest known host range for plasmid transfer in Gram-positive bacteria is organized in an operon encoding fifteen putative transfer proteins. In this project all transfer proteins shall be purified in small scale and checked for solubility and correct fold. All proteins fulfilling the criteria for crystallization will be expressed and purified in large scale. The putative pIP501-encoded type IV homologues, an ATPase, a coupling protein and a lytic transglycosylase will be functionally characterized. Crystallization trials will be performed for the three putative type IV homologous pIP501 proteins, for their analogues from the related plasmids pSK41 and pMRC01 and other members of the transfer operon, which are emerging from the yeast-two-hybrid screen and pull-down assays as key players in the conjugative transfer. Interactions found by these assays will be verified and characterized by biophysical methods. This project aims to elucidate the role and importance of the protein components for the assembly of a conjugative type IV-like secretion-machinery in Gram-positive bacteria.

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Auxiliary Functions

Head of Chair

Prof. Dr. rer. nat. Ulrich Szewzyk
BH 6-1
BH-N 604
Tel +49 30 314 73 461


Bärbel Minx
BH 6-1
BH-N 603
Tel +49 30 314 73 460

Consultation hours:
Mon - Fri

Adress Chair of Environmental Microbiology

Environmental Microbiology
of Environmental Technology
Faculty of Process Sciences
BH 6-1
Ernst-Reuter-Platz 1
10587 Berlin
Tel +49 30 314 73 460
Fax +49 30 314 73 673