A new phosphatase from an Antarctic bacterium: Molecular basis of cold adaptation mechanism

ARAN M, SMAL C., GALLO M., PELLIZZA L. AND CICERO D.

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2012

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

A new bacterial strain designated as JUB59 was isolated from the Antarctic sea surface and rouped into the Flavobacteriaceae family. The bacterium was identified as a new species within thegenus Bizionia and named Bizionia argentinensis (BA). Its genome was recently sequenced and represents an important source for the discovery of new proteins with biological activity at lowtemperatures. In order to structurally characterize a group of proteins of unknown function of BA, we carried out a method based on the selection of protein targets by NMR. By this method we were able to select proteins that given its solubility and folding became good candidates for structural determinations. Here, we present the solution structure of one of the selected targets, the protein BA42, revealing a previously unknown sequence/structure pair. By comparing the 3D structure of BA42 with existing databases, we characterize the phosphatase activity in vitro. This activity was dependent on divalent ions, particularly Mg . We also identified the key residues involved in the active site: E5 and K37.Asmaller number of interactions and a more flexible structure of the active site, compared with the mesophilic counterpart, may explain themolecular basis of the cold adaptation mechanism.