Transfer of information is a basic property of biological systems. Common examples include transfer of genetic information or nerve impulses.
Transmission of signals occurs at an even more fundamental level between and within cells, including signaling molecules, which bear a phosphate or a sulfate group. The latter contain a sulfur atom. Since these processes are of supreme importance, they have been extensively studied and a number of mechanisms and related protein structures have been revealed. Thus, it is even more surprising that ETH Zurich researchers studying transfer processes among sulfurylated molecules discovered a protein, sulfotransferase, whose function is known but which exhibits a previously unknown structure. The group of Rudi Glockshuber recently published a paper about the protein, called ASST, in the scientific journal PNAS.
ETH Zurich researchers crossed the disulfide bridge
The discovery of the signal transfer mechanism happened accidentally, as is often the case in scientific research. The Glockshuber group studies protein folding mechanisms, where bonds between two sulfur atoms in a protein chain, disulfide bridges, play an important role. While examining gene data banks, the researchers stumbled upon an unusual gene combination present in strains of E. coli which cause urinary tract infections: two genes for the disulfide bond formation machinery were clustered with the gene for ASST.
Since bacteria often contain functionally-related genes close to each other, the researchers decided to use ASST to study disulfide bond formation.
Hence, they decided to elucidate the structure of ASST. This turned out to be a tantalizing task because this protein is large and present in only minute amounts in a bacterial compartment called periplasm. By growing large-scale bacterial cultures the scientists could obtain sufficient material for crystallographic studies. The crystals of ASST
|Contact: Prof. Rudi Glockshuber|
ETH Zurich/Swiss Federal Institute of Technology