Bacterial Predators: Bdellovibrio Genome Project

New model for adhesion and invasion

The life cycle of Bdellovibrio based on previous data is being extended accordingly to the predicted physiology. Such, a new model is described for the adhesion and invasion process in which the presence of twitching motility can specify an active pulling of the cell into the host cell.
This is supported by the fact, that the flagella is shed off during the host entry and so a flagella driven process can be excluded. Furthermore, electron micrographs also show pili structures at the attachment pole on the opposite end to the flagella.

One candidate for defining independent growth is a previously described so called hit-locus, in which an unexpected high mutation rate could be observed in mutants which were isolated by independent growth.We could identify the localisation of this 950bp region to be part of a much larger pili and adhesion cluster inserted between two chemotaxis genes which also supports the role of pili involvement during invasion.

Absence of type III and type IV secretion systems

In its life cycle Bdellovibrio grows and develops in the periplasm of its prey. The fact that the cell keeps its prey cell alive while residuing in the compartment outside the cytosol needs an accurate invasion capability and is probably to keep the prey producing proteins and other gene products, as well as to escape a possible immunological response of a larger eukaryotic host in which the prey itself may be present.

Understanding the modes of operation and the absence of type III and type IV secretion systems encourages for the development of Bdellovibrio as basis for antibiotics as in addition no reports of invading mammalian cells are known. The identification of a large hydrolytic complement may also provide a valuable reservoir of enzyme-based anti-microbial substances.

Bdellovibrio lacks biosynthesis pathways for some essential amino acids

One of the major findings so far is the organism lacking complete biosynthesis pathways for some essential amino acids. A high density of transporter systems could be identified which is likely to compensate this lack.

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[sciencemag.org]

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Personnel:	Dr. Stephan C. Schuster Daniela Drautz
Collaborators:	Dr. Dieter Oesterhelt (Max-Planck-Institute for Biochemistry, Martinsried, Germany) Dr. Frank Siedler (Max-Planck-Institute for Biochemistry, Martinsried, Germany) Dr. R. Elisabeth Sockett (University of Nottingham, Nottingham, UK) Dr. Folker Meyer (University of Bielefeld, Bielefeld, Germany) Collaboration links
Key Publications:	Rendulic, S., Jagtap, P., Rosinus, A., Eppinger, M., Baar, C., Lanz, C., Keller, H., Lambert, C., Evans, K.J., Goesmann, A., Meyer, F., Sockett, R.E., & Schuster, S.C. (2003). A Predator Unmasked: Life Cycle of Bdellovibrio bacteriovorus from a Genomic Perspective. Science 303, 689-692.