Phosphate content in higher organisms is riddled

Mechanism of biosynthesis of polyphosphates decodes

Structural model of the VTC4p * complexed with a polyphosphate chain synthesized from ATP. The surface of the protein is transparent, inside the secondary structure elements are shown as a band model. The ATP binds as the source of phosphate at the site of the enzyme labeled with the star, and linear polyphosphates are formed through a tunnel-shaped opening of the protein. © RUB
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So-called polyphosphate chains play an important role in many organisms, for example to ensure cell growth even under deficiency conditions. However, little was known about their formation and functioning. But now an international team of scientists has gained fundamental insights into the manufacturing mechanism of polyphosphate chains.

In their new study, the researchers have succeeded in determining the first X-ray structure of the enzyme responsible for the construction of higher-developed organisms (eukaryotes) and to characterize essential biochemical processes. Based on the results, the catalytic processes can be described precisely at the molecular level.

Thus, the basis for further, targeted research activities on the role of polyphosphates created, the chemists and biochemists of the Ruhr University Bochum (RUB) report together with researchers from the European Molecular Biology Laboratory in Heidelberg and the University of Lausanne in "Science".

Characterization is a milestone

The enzyme VTC - vacuolar transporter chaperone - uses the cellular energy universal ATP to build up phosphate chains step by step. This creates a deposit that the organism can access under stress conditions. Using structural biological and biophysical methods, the researchers were able to show with which molecular aids the enzyme realizes the conversion of the phosphates from the source to the depot.

"It is particularly interesting that the structure of the chain-shaped Depot substance and their simultaneous transport into a cellular subunit using a tunnel-like protein structure, " explains Professor Christian Herrmann of the Chair of Physical Chemistry I of the RUB. The enzyme VTC is part of a larger protein complex that passes through an inner membrane of the cell. His characterization represents a milestone in the study of ATP-dependent membrane processes

Important protein research

At the Ruhr-Universität a special strength in the field of protein research has been established in recent years, which is mainly due to the successful continuation of the Collaborative Research Center 642 - ATP- and GTP-dependent membrane processes - and the Founding of the protein research department shows.

The special experimental equipment and experience of the scientists working there create the basis for tackling and promptly resolving the problems of modern life sciences with the necessary efficiency in an international, highly competitive research environment.

Young researchers successful

Erfre Particularly pleasing in this context is the fact that the biochemist Mark Wehner, as a scholarship holder from the RUB Research School, has made the essential contribution on the Bochum side and thus supports the concept of promoting young scientists in the context of the Excellence Initiative is confirmed, "emphasizes Herrmann.

(idw - Ruhr-University Bochum, 29.04.2009 - DLO)