engleski

STRUCTURE AND FUNCTION OF UNUSUAL ARCHAEAL SERYL-tRNA SYNTHETASE

Inspection of the known genomic sequences reveals that two dissimilar seryl-tRNA synthetases (SerRSs) occurs in different organisms: one of bacterial type, and a diverged one present only in some members of the methanogenic archaea. We have determined the crystal structure of the diverged SerRS from Methanosarcina barkeri at 2.1 angstrom resolution, which reveals a novel and unique tRNA-binding domain among synthetases. Additionaly, the structure reveals zinc ion in the active site of the catalytic domain, which has not been observed in the structure of bacterial type SerRS. In order to understand the role of zinc ion in the mechanism of amino acid discrimination by atypical SerRS we have solved the structure of the protein in complex with serine, ATP, stable analog of seryl-adenylate, 5� -O-(N-(L-seryl)sulfamoyl)adenosine. The zinc ion is directly involved in serine recognition by forming a pentacoordinate intermediate with both the amino group and the hydroxyl group of the side chain.

Archaeal Seryl-tRNA synthetase

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